Magnesium
Benefits
Magnesium plays a key role in hundreds of cellular processes, from metabolizing food into energy and absorbing calcium to maintaining a strong immune system and keeping your heart, muscles, and nerves functioning properly.
RealAge Recommendation
Government guidelines suggest 420 milligrams (mg) per day for men, 320 mg for women. RealAge recommends that both men and women aim to get 400–500 mg of magnesium per day. It may be tough to get all the magnesium you need from food, so top up your daily intake with a multivitamin that contains at least 100 mg of magnesium.
If you are pregnant or lactating, have kidney disease or diabetes, are on a low-calorie diet, or are taking digitalis preparations or diuretics, talk to your doctor about how much magnesium you should be getting.
Good Sources
Spinach, cooked (1 cup) 156 mg
Halibut, cooked (3 ounces) 91 mg
Cashews (1/4 cup) 89 mg
Oat-bran muffin (1 medium) 89 mg
White beans, canned (1/2 cup) 67 mg
Bran cereal (3/4 cup) 64 mg
Brown rice, cooked (3/4 cup) 63 mg
Potato, baked, with skin (1 medium) 57 mg
Whole-wheat bread (2 slices) 46 mg
Walnuts (1 ounce; 14 halves) 44 mg
Banana (1 medium) 32 mg
Calcium
Benefits
Calcium is essential for strong bones and teeth and helps prevent arthritis. But that’s not all this mineral is good for: Calcium helps your brain communicate with your nerves, regulates blood pressure, and may reduce the symptoms of PMS and the risk of colon cancer.
RealAge Recommendation
Government guidelines suggest 1,000–1,200 milligrams (mg) of calcium per day is adequate, but RealAge recommends a bit more: 1,000–1,500 mg of calcium per day from food and supplements -- but not all at once. Your body can only absorb 500–600 mg at a time, so divide it into two or three doses over the course of a day.
Tip: If you take a calcium supplement, take it with vitamin D (they’re often combined in one pill) to help absorption -- and with a little magnesium to reduce the constipation sometimes caused by calcium. Don’t pair calcium with iron or fiber supplements, which can interfere with your body’s ability to absorb the bone-building mineral.
Good Sources
Yogurt, plain, low-fat (8 ounces) 415 mg
Ricotta cheese from part-skim milk (1/2 cup) 335 mg
Soymilk, fortified (8 ounces) 300 mg
Spinach, cooked from frozen (1 cup) 290 mg
Milk, 2% milk fat (8 ounces) 285 mg
Swiss cheese, shredded (1/4 cup) 214 mg
Cheddar cheese, shredded (1/4 cup) 204 mg
Salmon, canned (3 ounces) 181 mg
Soybeans/edamame (1/2 cup) 130 mg
Tofu (3 ounces) 100 mg
Parmesan cheese, shredded (1 tablespoon) 55 mg
Omega-3 fatty acids
Benefits
Omega-3 fatty acids are the good-for-you fats that protect your heart by reducing your risk for cardiovascular disease. Omega-3s also have anti-inflammatory properties that may help fight disease, boost your mind and mood, and reduce symptoms of inflammatory conditions such as rheumatoid arthritis.
RealAge Recommendation
Think Threes: Eating 3 ounces of nonfried fish -- rich in omega-3 fatty acids -- three times a week can make your RealAge up to 3 years younger. Not a fish lover? Many nuts, seeds, and plant oils are good sources, too.
Good Sources
Cold-water fish tend to have the highest levels of omega-3 fatty acids. Try these:
• Salmon
• Haddock
• Trout
• Tuna
• Mackerel
• Sardines
• Cod
Nuts and seeds -- and their oils -- are also good sources for omega-3s:
• Flaxseeds and flaxseed oil
• Pumpkin seeds
• Walnuts
• Canola oil
• Olive oil
Potassium
Benefits
Potassium helps regulate blood pressure and maintain normal heart and artery function. It also reduces the risk of stroke.
RealAge Recommendation
We currently recommend getting at least 3,000 milligrams (mg) of potassium per day from food, but we’re reviewing the latest science and expect our recommendation to increase -- so watch this space! The government now advises 4,700 mg per day. That said, don’t take a potassium supplement unless directed by your physician, because too much of this mineral can be toxic. Some multivitamins contain potassium, but only in small amounts, so don’t panic if yours is one of them -- just make sure it’s less than 100 mg.
Good Sources
Potato, baked, with skin (1 medium) 1,082 mg
Sweet potato, baked, with skin (1 medium) 694 mg
White beans, canned (1/2 cup) 595 mg
Yogurt, low fat (8 ounces) 531 mg
Beets, cooked (1 cup) 519 mg
Halibut, cooked (3 ounces) 490 mg
Banana (1 medium) 422 mg
Kidney beans, canned (1/2 cup) 328 mg
Raisins (1.5-ounce box) 322 mg
Salmon, cooked (3 ounces) 319 mg
Blackberries (1 cup) 233 mg
Selenium
Benefits
Selenium is a trace mineral, which means your body needs it, but only in very small amounts. Selenium helps keep your immune system strong and may reduce the risk of some cancers.
RealAge Recommendation
Government guidelines recommend 55 micrograms (mcg) of selenium per day, but for optimal health and disease prevention, RealAge recommends that you up that to 200 mcg per day. And we believe it’s best to get this mineral from food, not supplements. Too much selenium can be toxic, so don’t overdo it -- keep your daily intake below 400 mcg.
Good Sources
Brazil nuts (1/2 ounce; 3–4 nuts) 270 mcg
Tuna, canned (3 ounces) 65 mcg
Couscous, cooked (1 cup) 43 mcg
Halibut, cooked (3 ounces) 40 mcg
Pasta, cooked (1 cup) 37 mcg
Pork (3 ounces) 30–40 mcg
Salmon, cooked (3 ounces) 32 mcg
Turkey or chicken, light meat (3 ounces) 24–27 mcg
Bagel (1 medium) 27 mcg
Ground beef, cooked (3 ounces) 18–24 mcg
Zinc
Benefits
Zinc is an essential mineral that helps wounds heal and keeps your immune system strong. But does it help prevent colds? Find out here.
RealAge Recommendation
To prevent deficiency, the current government guidelines recommend 11 milligrams (mg) of zinc per day for men and 8 mg for women. For optimal health and disease prevention, RealAge recommends adults get 12 mg of zinc per day, preferably through food. Too much zinc can interfere with your body’s ability to absorb other vitamins and minerals, so if you take a daily supplement or multivitamin, opt for one with no more than 15 mg of zinc.
Good Sources
Oysters, raw (3 medium) 16–25 mg
Lamb chop (3 ounces) 6 mg
Ground beef, 85% lean (3 ounces) 5.3 mg
Ricotta cheese, part-skim milk (1 cup) 3.3 mg
Turkey, no skin (3 ounces) 2.6 mg
Kidney beans, canned (1/2 cup) 2 mg
Yogurt, plain, low-fat (8 ounces) 2 mg
Shiitake mushrooms (1 cup) 2 mg
Sunflower seeds (1/4 cup) 1.7 mg
Almonds (1/4 cup) 0.8 mg
Beta Carotene
Benefits
Beta carotene is a type of carotenoid found in many fruits and vegetables. You don’t need beta carotene to survive, though it may help fight off certain diseases. Also, your body can convert it into vitamin A, which you do need.
RealAge Recommendation
There’s no specific RealAge recommendation for how much beta carotene you should get, but we recommend that you get it from fruits and veggies, not supplements; high-dose supplements (of 30 milligrams or more a day) have been linked to an increased risk of lung cancer.
Good Sources
You’ll get plenty of beta carotene from the foods below. And eating a diverse diet that includes 4 servings of fruit and 5 servings of vegetables per day can make your RealAge as much as 4 years younger.
• Carrots
• Pumpkin and butternut squash
• Sweet potatoes
• Spinach
• Kale
• Cantaloupe
• Apricots
• Mango
• Nectarines
Yogurt, plain, low-fat (8 ounces) 415 mg
Ricotta cheese from part-skim milk (1/2 cup) 335 mg
Soymilk, fortified (8 ounces) 300 mg
Spinach, cooked from frozen (1 cup) 290 mg
Milk, 2% milk fat (8 ounces) 285 mg
Swiss cheese, shredded (1/4 cup) 214 mg
Cheddar cheese, shredded (1/4 cup) 204 mg
Salmon, canned (3 ounces) 181 mg
Soybeans/edamame (1/2 cup) 130 mg
Tofu (3 ounces) 100 mg
Parmesan cheese, shredded (1 tablespoon) 55 mg
Spinach, cooked (1 cup) 230 mcg
Lentils, cooked (1/2 cup) 180 mcg
Papayas (1 medium) 116 mcg
Artichokes, cooked (1 medium) 107 mcg
Asparagus, boiled (4 spears) 89 mcg
Avocados (1/2 medium) 81 mcg
Raspberries (1 cup) 65 mcg
Black-eyed peas, canned (1/2 cup) 61 mcg
Red bell peppers (1 medium) 55 mcg
Oranges (1 medium) 39 mcg
Shiitake mushrooms, cooked (1/2 cup) 15mcg
Cereal
Total Raisin Bran (1 cup) 18 mg
Cheerios (1 cup) 9.5 mg
Spinach, cooked (1 cup) 6.4 mg
Oysters, raw (6 medium) 5.5 mg
Kidney beans, cooked (1/2 cup) 3.6 mg
Tomatoes, canned (1 cup) 3.4 mg
Lentils, cooked (1/2 cup) 3 mg
Ground beef, 85% lean (3 ounces) 2.2 mg
Lima beans, cooked from frozen (1/2 cup) 1.8 mg
Spinach, cooked (1 cup) 156 mg
Halibut, cooked (3 ounces) 91 mg
Cashews (1/4 cup) 89 mg
Oat-bran muffin (1 medium) 89 mg
White beans, canned (1/2 cup) 67 mg
Bran cereal (3/4 cup) 64 mg
Brown rice, cooked (3/4 cup) 63 mg
Potato, baked, with skin (1 medium) 57 mg
Whole-wheat bread (2 slices) 46 mg
Walnuts (1 ounce; 14 halves) 44 mg
Banana (1 medium) 32 mg
Potato, baked, with skin (1 medium) 1,082 mg
Sweet potato, baked, with skin (1 medium) 694 mg
White beans, canned (1/2 cup) 595 mg
Yogurt, low fat (8 ounces) 531 mg
Beets, cooked (1 cup) 519 mg
Halibut, cooked (3 ounces) 490 mg
Banana (1 medium) 422 mg
Kidney beans, canned (1/2 cup) 328 mg
Raisins (1.5-ounce box) 322 mg
Salmon, cooked (3 ounces) 319 mg
Blackberries (1 cup) 233 mg
Brazil nuts (1/2 ounce; 3–4 nuts) 270 mcg
Tuna, canned (3 ounces) 65 mcg
Couscous, cooked (1 cup) 43 mcg
Halibut, cooked (3 ounces) 40 mcg
Pasta, cooked (1 cup) 37 mcg
Pork (3 ounces) 30–40 mcg
Salmon, cooked (3 ounces) 32 mcg
Turkey or chicken, light meat (3 ounces) 24–27 mcg
Bagel (1 medium) 27 mcg
Ground beef, cooked (3 ounces) 18–24 mcg
Cereal
Total Raisin Bran (1 cup) 2.0 mg
Kellogg’s Special K (1 cup) 1.9 mg
Tuna, fresh, cooked (3 ounces) 0.9 mg
Potato, baked, with skin (1 medium) 0.6 mg
Chickpeas, canned (1/2 cup) 0.5 mg
Chicken breast, roasted, no skin (3 ounces) 0.5 mg
Banana (1 medium) 0.4 mg
Broccoli, boiled (1 cup) 0.3 mg
Sunflower seeds (1/4 cup) 0.2 mg
Tomato sauce, canned (1/2 cup) 0.1 mg
Carrots, raw (1 cup) 0.1 mg
Clams, canned (3 ounces) 84 mcg
Liver, calf’s, pan-fried (3 ounces) 70 mcg
Oysters, raw (6 medium) 16 mcg
Salmon, canned (3 ounces) 4 mcg
Tuna, light, canned in water (3 ounces) 2.5 mcg
Nutritional yeast (2 teaspoons) 2.5 mcg
Ground beef, 85% lean (3 ounces) 2 mcg
Lamb, loin chop (3 ounces) 2 mcg
Yogurt, plain, low-fat (8 ounces) 1.3 mcg
Cottage cheese, 2% milk fat (1/2 cup) 0.8 mcg
Peaches, frozen and sweetened (1 cup) 235 mg
Red bell pepper, raw (1 medium) 152 mg
Broccoli florets, cooked (1 cup) 101 mg
Strawberries (1 cup) 97 mg
Green bell pepper, raw (1 medium) 96 mg
Papaya (1 cup) 86 mg
Kiwifruit (1 medium) 70 mg
Orange (1 medium) 70 mg
Cantaloupe (1 cup) 59 mg
Mango (1 medium) 57 mg
Brussels sprouts, cooked (4 medium) 52 mg
Salmon, canned (3 ounces) 530 IU
Salmon, cooked (3.5 ounces) 240–360 IU
Tuna, canned (3 ounces) 200 IU
Soymilk, fortified (8 ounces) 100 IU
Orange juice, fortified (8 ounces) 100 IU
Milk, low-fat, fortified (8 ounces) 98 IU
Cereal, fortified (1 cup) 40–50 IU
Eggs (1 large) 20–26 IU
Swiss cheese (1 ounce) 12 IU
Cereal: raisin bran, corn flakes (1 cup) 20 IU
Almonds (1/4 cup) 14 IU
Sunflower seeds (1/4 cup) 12 IU
Spinach, cooked from frozen (1 cup) 10 IU
Hazelnuts (1/4 cup) 8 IU
Safflower oil (1 tablespoon) 7 IU
Red bell pepper (1 cup) 4 IU
Avocado (1/2 medium) 3 IU
Olive oil (1 tablespoon) 3 IU
Mango (1 medium) 3 IU
Tomatoes, canned (1 cup) 3 IU
Kale, cooked (1 cup) 1060 mcg
Spinach, cooked (1 cup) 888 mcg
Broccoli, cooked (1 cup) 220 mcg
Spinach, raw (1 cup) 150 mcg
Brussels sprouts, cooked (4 sprouts) 118 mcg
Okra, cooked (1 cup) 64 mcg
Lettuce, romaine (1 cup) 57 mcg
Asparagus (4 spears) 30 mcg
Kiwifruit (1 medium) 30 mcg
Blueberries (1 cup) 28 mcg
Oysters, raw (3 medium) 16–25 mg
Lamb chop (3 ounces) 6 mg
Ground beef, 85% lean (3 ounces) 5.3 mg
Ricotta cheese, part-skim milk (1 cup) 3.3 mg
Turkey, no skin (3 ounces) 2.6 mg
Kidney beans, canned (1/2 cup) 2 mg
Yogurt, plain, low-fat (8 ounces) 2 mg
Shiitake mushrooms (1 cup) 2 mg
Sunflower seeds (1/4 cup) 1.7 mg
Almonds (1/4 cup) 0.8 mg
Lycopene
Benefits
Lycopene is a carotenoid that may boost heart health, prevent vision loss, and lower the risk of some cancers.
RealAge Recommendation
There’s no specific RealAge recommendation for lycopene, but it’s found primarily in fruit, so eat 4 servings of fruit each day -- which can make your RealAge up to 4 years younger.
Good Sources
The brighter the better. Pink, orange, and red fruits are generally rich in lycopene. For a lycopene boost, consider:
• Watermelon
• Tomatoes, tomato juice, and tomato sauce
• Papaya
• Pink grapefruit
• Guava
Tip: It’s easier for your body to absorb lycopene from tomatoes that have been cooked, canned, or otherwise processed. Adding a little bit of fat helps as well, so cook your tomatoes with a splash of heart-healthy olive oil.
Vitamin E
Benefits
Vitamin E is an antioxidant that may help prevent heart disease, Alzheimer’s, and two common vision stealers -- macular degeneration and cataracts.
RealAge Recommendation
Government guidelines recommend a daily intake of 22.5 international units (IU) of vitamin E, but this is only enough to prevent deficiency. For optimal health and disease prevention, RealAge recommends that you aim for 400 international units (IU) of vitamin E per day. It’s tough to get all the E you need from food alone, so top up your supply with a daily supplement.
Tip: Take your E with C (1,200 mg). These two antioxidant vitamins work together to prevent the oxidation that causes clogs in blood vessel walls, and pairing them on a daily basis can make your RealAge 3 years younger.
Good Sources
Cereal: raisin bran, corn flakes (1 cup) 20 IU
Almonds (1/4 cup) 14 IU
Sunflower seeds (1/4 cup) 12 IU
Spinach, cooked from frozen (1 cup) 10 IU
Hazelnuts (1/4 cup) 8 IU
Safflower oil (1 tablespoon) 7 IU
Red bell pepper (1 cup) 4 IU
Avocado (1/2 medium) 3 IU
Olive oil (1 tablespoon) 3 IU
Mango (1 medium) 3 IU
Tomatoes, canned (1 cup) 3 IU
Vitamin K
Benefits
Your body uses vitamin K to help stop bleeding after a cut or injury. And K may also play a role in building strong bones, preventing osteoporosis, and reducing inflammation that leads to heart disease.
RealAge Recommendation
Shoot for at least 90 micrograms (mcg) of vitamin K per day for women and 120 mcg for men. Most people get enough K from their diets, but if it looks like you’re getting more than the recommended amount, not to worry: You can’t overdo vitamin K from fruits and vegetables.
One note: Significant changes in vitamin K levels can interfere with blood-thinning drugs (such as warfarin), so if you’re taking a blood thinner, talk to your doctor about being consistent with your K intake.
Good Sources
Leafy green vegetables have the highest amounts of vitamin K, but other fruits and veggies have good supplies, too:
Kale, cooked (1 cup) 1060 mcg
Spinach, cooked (1 cup) 888 mcg
Broccoli, cooked (1 cup) 220 mcg
Spinach, raw (1 cup) 150 mcg
Brussels sprouts, cooked (4 sprouts) 118 mcg
Okra, cooked (1 cup) 64 mcg
Lettuce, romaine (1 cup) 57 mcg
Asparagus (4 spears) 30 mcg
Kiwifruit (1 medium) 30 mcg
Blueberries (1 cup) 28 mcg
Vitamin A
Benefits
Vitamin A helps maintain healthy eyes, skin, teeth, and bones. It’s also essential for cell division -- which means renewal -- and it plays a key role in keeping your immune system strong.
RealAge Recommendation
Your body doesn’t need much vitamin A, and too much (in supplement form) can harm your health, so it’s best to get your A the natural way: from plenty of fruit and vegetables.
If you take a daily multivitamin, make sure it contains no more than 2,500–3,000 international units (IU) of vitamin A and that it’s in the form of beta carotene (from plants). Your body regulates its supply of plant-based A -- also known as provitamin A -- by absorbing it slowly and flushing out any excess before it becomes harmful. But other types of A -- from animal sources, such as liver and giblets, as well as some supplements -- can build up in your system and become toxic. You need to limit these types, called preformed or retinol A.
Bottom line: If you stick to fruit and vegetable sources and an appropriate multivitamin, you should be A-OK.
Good Sources
Eggs, milk, and fortified cereals are good sources of preformed vitamin A. For plant-based provitamin A, the following foods are your best bets. If you’re not taking a multivitamin with A, try to include at least one serving of these foods in your daily mix:
• Carrots
• Sweet potatoes
• Pumpkin and squash
• Red bell pepper
• Spinach
• Cantaloupe
• Mango
• Broccoli
Folate (Vitamin B9)
Benefits
Folate -- also called folic acid -- is a B vitamin that protects against arterial aging, aids in the production of red blood cells and DNA, and helps reduce levels of homocysteine (an amino acid that may raise your risk of heart disease).
RealAge Recommendation
Aim to get 700 micrograms (mcg) of folate per day. The average daily diet contains about 300 mcg, so choose a multivitamin with 400 mcg of folic acid to top up your daily dose. Pregnant women and people who have cancer, severe burns, or skin diseases may need extra folate to maintain healthy levels.
Don’t exceed 1,000 mcg of folate per day -- too much could lead to nerve damage or vitamin B12 deficiency.
Good Sources
Many pastas, breads, cereals, grains, and fruit juices produced in the U.S. are fortified with folic acid. Check labels for details. Other food sources include:
Spinach, cooked (1 cup) 230 mcg
Lentils, cooked (1/2 cup) 180 mcg
Papayas (1 medium) 116 mcg
Artichokes, cooked (1 medium) 107 mcg
Asparagus, boiled (4 spears) 89 mcg
Avocados (1/2 medium) 81 mcg
Raspberries (1 cup) 65 mcg
Black-eyed peas, canned (1/2 cup) 61 mcg
Red bell peppers (1 medium) 55 mcg
Oranges (1 medium) 39 mcg
Shiitake mushrooms, cooked (1/2 cup) 15mcg
Iron
Benefits
One of the primary functions of iron is to pick up oxygen in the lungs and deliver it to the rest of your body. Iron is also important for DNA synthesis, which promotes growth, healing, and a strong immune system.
RealAge Recommendation
We agree with the current government guidelines that recommend a daily iron intake of 8 milligrams (mg) for men and 18 mg for women. If you’re pregnant, increase your daily amount to 27 mg, and if you’re past menopause, reduce it to 8 mg.
Good Sources
It’s best to get your iron from food, so don’t use supplements unless you’ve been diagnosed with iron deficiency or are at risk for it and have been instructed by your doctor to do so.
Cereal
Total Raisin Bran (1 cup) 18 mg
Cheerios (1 cup) 9.5 mg
Spinach, cooked (1 cup) 6.4 mg
Oysters, raw (6 medium) 5.5 mg
Kidney beans, cooked (1/2 cup) 3.6 mg
Tomatoes, canned (1 cup) 3.4 mg
Lentils, cooked (1/2 cup) 3 mg
Ground beef, 85% lean (3 ounces) 2.2 mg
Lima beans, cooked from frozen (1/2 cup) 1.8 mg
Vitamin C
Benefits
Vitamin C helps your body metabolize proteins into energy, boosts your immune system, builds collagen in your skin, promotes healing, and aids in joint repair. It also helps keep your arteries young and prevents fatty plaque buildup on blood vessel walls. Wow!
RealAge Recommendation
To prevent vitamin C deficiency, government guidelines recommend a daily dose of 90 milligrams (mg) for men, 75 mg for women. RealAge recommends that you get 1,200 mg of vitamin C per day from food and supplements to make your RealAge as much as 1 year younger. This higher amount not only prevents deficiency but also helps prevent disease and needless aging.
Good Sources
Peaches, frozen and sweetened (1 cup) 235 mg
Red bell pepper, raw (1 medium) 152 mg
Broccoli florets, cooked (1 cup) 101 mg
Strawberries (1 cup) 97 mg
Green bell pepper, raw (1 medium) 96 mg
Papaya (1 cup) 86 mg
Kiwifruit (1 medium) 70 mg
Orange (1 medium) 70 mg
Cantaloupe (1 cup) 59 mg
Mango (1 medium) 57 mg
Brussels sprouts, cooked (4 medium) 52 mg
The Truth About Vitamin D
Get answers to commonly asked questions about vitamin D.
By Daniel J. DeNoon
WebMD Feature
Reviewed by Brunilda Nazario, MD
The hottest topic in medicine isn't the newest drug or the latest surgical device: It's vitamin D.
What brought the simmering debate to a boil was a 2007 study showing that people taking normal vitamin D supplements were 7% less likely to die than those who didn't take the daily supplements.
A year later, a major study found that when women with low vitamin D levels get breast cancer, they have a much higher chance of dying from their cancer than women with normal vitamin D levels.
That was surprising news. But just as surprising is the fact that many men, women, and children have insufficient blood levels of this important vitamin.
How many? Data suggest many of us don't get the vitamin D we need. For example, a 2007 study of childbearing women in the Northern U.S. found insufficient vitamin D levels in 54% of black women and in 42% of white women.
These findings led the American Academy of Pediatrics to double the recommended amount of vitamin D a child should take -- and have led many doctors to advise their adult patients to up their vitamin D intake.
Your health may depend on knowing the answers to these important questions:
• Why do I need vitamin D?
• How can I get enough vitamin D?
• Will a vitamin D test tell me if I need more vitamin D?
• Which foods contain vitamin D?
• How much vitamin D do my children and I need?
• Can I get too much vitamin D?
• What kind of vitamin D is best?
• Does vitamin D interact with other medications?
Why do I need vitamin D?
• Your body must have vitamin D to absorb calcium and promote bone growth. Too little vitamin D results in soft bones in children (rickets) and fragile, misshapen bones in adults (osteomalacia). You also need vitamin D for other important body functions.
• Vitamin D deficiency has now been linked to breast cancer, colon cancer, prostate cancer, heart disease, depression, weight gain, and other maladies. These studies show that people with higher levels of vitamin D have a lower risk of disease, although they do not definitively prove that lack of vitamin D causes disease -- or that vitamin D supplements would lower risk.
• The Vitamin D Council -- a scientist-led group promoting vitamin D deficiency awareness -- suggests vitamin D treatment might be found helpful in treating or preventing autism, autoimmune disease, cancer, chronic pain, depression, diabetes, heart disease, high bloodpressure, flu, neuromuscular diseases, and osteoporosis. However, there have been no definitive clinical trials.
• The best known benefit of vitamin D is its role in helping calcium build strong bones. But that's far from the whole story. Vitamin D helps regulate the immune system and the neuromuscular system. Vitamin D also plays major roles in the life cycle of human cells.
• Vitamin D is so important that your body makes it by itself -- but only after skin exposure to sufficient sunlight. This is a problem for people in northern climates. In the U.S., only people who live south of a line drawn from Los Angeles to Columbia, S.C., get enough sunlight for vitamin D production throughout the year.
• Dark skin absorbs less sunlight, so people with dark skin do not get as much vitamin D from sun exposure as do light-skinned people. This is a particular problem for African-Americans in the northern U.S.
How can I get enough vitamin D?
Thirty minutes of sun exposure to the face, legs, or back -- without sunscreen -- at least twice a week should give you plenty of vitamin D.
But this much direct sun exposure might also expose you to potentially dangerous levels of cancer-causing UV radiation. And unless you live in the South or Southwest, you probably won't get enough sunlight during the winter months for your body to make enough vitamin D. The American Academy of Dermatology recommends against getting vitamin D from unprotected exposure to sunlight.
It's probably a better idea to get vitamin D from foods or from supplements.
Will a vitamin D test tell me if I need more vitamin D?
Yes. As part of your regular blood test, your doctor should order a test for 25-hydroxyvitamin D (25-OHD).
Everyone agrees that anyone with a 25-OHD level of less than 15 ng/mL or 37.5 nmol/L (depending on the units reported by a lab) needs more vitamin D. A 2002 study found that 42% of African-American women of childbearing age had vitamin D levels below 15 ng/mL.
The U.S. National Institutes of health notes that 25-OHD levels over 30 ng/mL are optimal, and that there is "insufficient data" to support recommendations for higher levels.
The Vitamin D Council considers the ideal 25-OHD level to be between 40 ng/mL and 70 ng/mL.
Which foods contain vitamin D?
Surprisingly few foods contain vitamin D -- unless it's added to the food. That's because your body is built to get vitamin D through your skin (from sunlight) rather than through your mouth (by food). But once your body has enough, it doesn't matter whether you got it through your skin or through your stomach.
There are three vitamin D super foods:
• Salmon (especially wild-caught)
• Mackerel (especially wild-caught; eat up to 12 ounces a week of a variety of fish and shellfish that are low in mercury)
• Mushrooms exposed to ultraviolet light to increase vitamin D
Other food sources of vitamin D include:
• Cod liver oil (warning: cod liver oil is rich in vitamin A; too much may be bad for you)
• Tuna canned in water
• Sardines canned in oil
• Milk or yogurt -- regardless of whether it's whole, nonfat, or reduced fat -- fortified with vitamin D
• Beef or calf liver
• Egg yolks
• Cheese
Nearly all milk in the U.S. is fortified with vitamin D. So are many brands of orange juice, yogurt, margarine, and ready-to-eat breakfast cereals.
How much vitamin D do I need?
The current recommended daily dose of vitamin D is 200 IU for people up to age 50, 400 IU for people aged 51 to 70, and 600 IU for people over age 70.
That's not enough, Boston University vitamin D expert , MD, PhD, tells WebMD. Holick recommends a dose of 1,000 IU a day of vitamin D for both infants and adults -- unless they're getting plenty of safe sun exposure.
In 2008, the American Academy of Pediatrics recommended that breastfed infants receive 400 IU of vitamin D every day until they are weaned. This doubled the AAP's previous recommendation.
The AAP also recommends 400 IU/day of vitamin D for children and teens who drink less than a quart of vitamin D-fortified milk per day.
The Vitamin D Council recommends that healthy adults take 2,000 IU of vitamin D daily -- more if they get little or no sun exposure.
There's evidence that people with a lot of body fat need more vitamin D than lean people.
The Institute of Medicine's Food and Nutrition Board is currently updating its 1997 vitamin D recommendations. A report is scheduled for May 2010.
Can I get too much vitamin D?
Too much of any good thing is a bad thing. Too much vitamin D can cause an abnormally high blood calcium level, which could result in nausea, constipation, confusion, abnormal heart rhythm, and even kidney stones.
It's nearly impossible to get too much vitamin D from sunlight or from foods (unless you take way too much cod liver oil). Nearly all vitamin D overdoses come from supplements.
The Institute of Medicine's Food and Nutrition Board's 1997 recommendations -- scheduled for a May 2010 update -- suggest that 2,000 IU per day of vitamin D is safe for adults and that 1,000 IU per day is safe for infants up to 12 months of age.
However, the relatively small doses of vitamin D in daily vitamin pills are not enough to correct serious vitamin D deficiency. A 2009 study suggested that the best regimen for treating vitamin D insufficiency is 50,000 IU of vitamin D3 taken three times a week for six weeks. This time-limited regimen did not result in vitamin D toxicity.
How much vitamin D is too much? That's controversial. According to the National Institutes of Health, the maximum upper limit for vitamin D is 25 micrograms (1,000 IU) for children up to age 12 months and 50 micrograms (2,000 IU) for everyone else.
But some recent studies suggest that healthy adults can tolerate more than 10,000 IU of vitamin D per day. John Jacob Cannell, MD, executive director of The Vitamin D Council, notes that the skin makes 10,000 IU of vitamin D after 30 minutes of full-body sun exposure. He suggests that 10,000 IU of vitamin D is not toxic.
According to the National Institutes of Health, 25-OHD levels that are consistently over 200 ng/mL are "potentially toxic."
What kind of vitamin D is best?
The recommended form of vitamin D is vitamin D3 or cholecalciferol. This is the natural form of vitamin D that your body makes from sunlight. Supplements are made from the fat of lambs' wool.
However, a clinical study reported in 2008 suggested that vitamin D2 works as well as vitamin D3.
Many supplements contain vitamin D as vitamin D2 or calciferol. It's derived from irradiated fungus. Because this is not the form of vitamin D naturally made by your body, WebMD nutritionist Kathleen M. Zelman, MPH, RD, recommends using the D3 form for those taking vitamin D supplements.
Because of its potency, different forms of vitamin D are used in prescription medications. If you have a prescription for one of these medications, do not switch to another form of vitamin D without checking with your doctor.
Does vitamin D interact with other medications?
Yes. Steroid medications such as prednisone can interfere with vitamin D metabolism. If you take steroid drugs regularly, discuss vitamin D with your doctor.
The weight loss drug orlistat -- brand names include Xenical and Alli -- may cut absorption of vitamin D. So does the cholesterol-lowering drug cholestyramine (sold as Questran, LoCholest, and Prevalite). People taking these drugs should discuss vitamin intake with their doctors.
The seizure drugs Phenobarbital and Dilantin (phenytoin), affect vitamin D metabolism and affect calcium absorption. So do anti-tuberculosis drugs.
On the other hand, cholesterol-lowering statin drugs and thiazide diuretics increase vitamin D levels.
Benefits
Magnesium plays a key role in hundreds of cellular processes, from metabolizing food into energy and absorbing calcium to maintaining a strong immune system and keeping your heart, muscles, and nerves functioning properly.
RealAge Recommendation
Government guidelines suggest 420 milligrams (mg) per day for men, 320 mg for women. RealAge recommends that both men and women aim to get 400–500 mg of magnesium per day. It may be tough to get all the magnesium you need from food, so top up your daily intake with a multivitamin that contains at least 100 mg of magnesium.
If you are pregnant or lactating, have kidney disease or diabetes, are on a low-calorie diet, or are taking digitalis preparations or diuretics, talk to your doctor about how much magnesium you should be getting.
Good Sources
Spinach, cooked (1 cup) 156 mg
Halibut, cooked (3 ounces) 91 mg
Cashews (1/4 cup) 89 mg
Oat-bran muffin (1 medium) 89 mg
White beans, canned (1/2 cup) 67 mg
Bran cereal (3/4 cup) 64 mg
Brown rice, cooked (3/4 cup) 63 mg
Potato, baked, with skin (1 medium) 57 mg
Whole-wheat bread (2 slices) 46 mg
Walnuts (1 ounce; 14 halves) 44 mg
Banana (1 medium) 32 mg
Calcium
Benefits
Calcium is essential for strong bones and teeth and helps prevent arthritis. But that’s not all this mineral is good for: Calcium helps your brain communicate with your nerves, regulates blood pressure, and may reduce the symptoms of PMS and the risk of colon cancer.
RealAge Recommendation
Government guidelines suggest 1,000–1,200 milligrams (mg) of calcium per day is adequate, but RealAge recommends a bit more: 1,000–1,500 mg of calcium per day from food and supplements -- but not all at once. Your body can only absorb 500–600 mg at a time, so divide it into two or three doses over the course of a day.
Tip: If you take a calcium supplement, take it with vitamin D (they’re often combined in one pill) to help absorption -- and with a little magnesium to reduce the constipation sometimes caused by calcium. Don’t pair calcium with iron or fiber supplements, which can interfere with your body’s ability to absorb the bone-building mineral.
Good Sources
Yogurt, plain, low-fat (8 ounces) 415 mg
Ricotta cheese from part-skim milk (1/2 cup) 335 mg
Soymilk, fortified (8 ounces) 300 mg
Spinach, cooked from frozen (1 cup) 290 mg
Milk, 2% milk fat (8 ounces) 285 mg
Swiss cheese, shredded (1/4 cup) 214 mg
Cheddar cheese, shredded (1/4 cup) 204 mg
Salmon, canned (3 ounces) 181 mg
Soybeans/edamame (1/2 cup) 130 mg
Tofu (3 ounces) 100 mg
Parmesan cheese, shredded (1 tablespoon) 55 mg
Omega-3 fatty acids
Benefits
Omega-3 fatty acids are the good-for-you fats that protect your heart by reducing your risk for cardiovascular disease. Omega-3s also have anti-inflammatory properties that may help fight disease, boost your mind and mood, and reduce symptoms of inflammatory conditions such as rheumatoid arthritis.
RealAge Recommendation
Think Threes: Eating 3 ounces of nonfried fish -- rich in omega-3 fatty acids -- three times a week can make your RealAge up to 3 years younger. Not a fish lover? Many nuts, seeds, and plant oils are good sources, too.
Good Sources
Cold-water fish tend to have the highest levels of omega-3 fatty acids. Try these:
• Salmon
• Haddock
• Trout
• Tuna
• Mackerel
• Sardines
• Cod
Nuts and seeds -- and their oils -- are also good sources for omega-3s:
• Flaxseeds and flaxseed oil
• Pumpkin seeds
• Walnuts
• Canola oil
• Olive oil
Potassium
Benefits
Potassium helps regulate blood pressure and maintain normal heart and artery function. It also reduces the risk of stroke.
RealAge Recommendation
We currently recommend getting at least 3,000 milligrams (mg) of potassium per day from food, but we’re reviewing the latest science and expect our recommendation to increase -- so watch this space! The government now advises 4,700 mg per day. That said, don’t take a potassium supplement unless directed by your physician, because too much of this mineral can be toxic. Some multivitamins contain potassium, but only in small amounts, so don’t panic if yours is one of them -- just make sure it’s less than 100 mg.
Good Sources
Potato, baked, with skin (1 medium) 1,082 mg
Sweet potato, baked, with skin (1 medium) 694 mg
White beans, canned (1/2 cup) 595 mg
Yogurt, low fat (8 ounces) 531 mg
Beets, cooked (1 cup) 519 mg
Halibut, cooked (3 ounces) 490 mg
Banana (1 medium) 422 mg
Kidney beans, canned (1/2 cup) 328 mg
Raisins (1.5-ounce box) 322 mg
Salmon, cooked (3 ounces) 319 mg
Blackberries (1 cup) 233 mg
Selenium
Benefits
Selenium is a trace mineral, which means your body needs it, but only in very small amounts. Selenium helps keep your immune system strong and may reduce the risk of some cancers.
RealAge Recommendation
Government guidelines recommend 55 micrograms (mcg) of selenium per day, but for optimal health and disease prevention, RealAge recommends that you up that to 200 mcg per day. And we believe it’s best to get this mineral from food, not supplements. Too much selenium can be toxic, so don’t overdo it -- keep your daily intake below 400 mcg.
Good Sources
Brazil nuts (1/2 ounce; 3–4 nuts) 270 mcg
Tuna, canned (3 ounces) 65 mcg
Couscous, cooked (1 cup) 43 mcg
Halibut, cooked (3 ounces) 40 mcg
Pasta, cooked (1 cup) 37 mcg
Pork (3 ounces) 30–40 mcg
Salmon, cooked (3 ounces) 32 mcg
Turkey or chicken, light meat (3 ounces) 24–27 mcg
Bagel (1 medium) 27 mcg
Ground beef, cooked (3 ounces) 18–24 mcg
Zinc
Benefits
Zinc is an essential mineral that helps wounds heal and keeps your immune system strong. But does it help prevent colds? Find out here.
RealAge Recommendation
To prevent deficiency, the current government guidelines recommend 11 milligrams (mg) of zinc per day for men and 8 mg for women. For optimal health and disease prevention, RealAge recommends adults get 12 mg of zinc per day, preferably through food. Too much zinc can interfere with your body’s ability to absorb other vitamins and minerals, so if you take a daily supplement or multivitamin, opt for one with no more than 15 mg of zinc.
Good Sources
Oysters, raw (3 medium) 16–25 mg
Lamb chop (3 ounces) 6 mg
Ground beef, 85% lean (3 ounces) 5.3 mg
Ricotta cheese, part-skim milk (1 cup) 3.3 mg
Turkey, no skin (3 ounces) 2.6 mg
Kidney beans, canned (1/2 cup) 2 mg
Yogurt, plain, low-fat (8 ounces) 2 mg
Shiitake mushrooms (1 cup) 2 mg
Sunflower seeds (1/4 cup) 1.7 mg
Almonds (1/4 cup) 0.8 mg
Beta Carotene
Benefits
Beta carotene is a type of carotenoid found in many fruits and vegetables. You don’t need beta carotene to survive, though it may help fight off certain diseases. Also, your body can convert it into vitamin A, which you do need.
RealAge Recommendation
There’s no specific RealAge recommendation for how much beta carotene you should get, but we recommend that you get it from fruits and veggies, not supplements; high-dose supplements (of 30 milligrams or more a day) have been linked to an increased risk of lung cancer.
Good Sources
You’ll get plenty of beta carotene from the foods below. And eating a diverse diet that includes 4 servings of fruit and 5 servings of vegetables per day can make your RealAge as much as 4 years younger.
• Carrots
• Pumpkin and butternut squash
• Sweet potatoes
• Spinach
• Kale
• Cantaloupe
• Apricots
• Mango
• Nectarines
Yogurt, plain, low-fat (8 ounces) 415 mg
Ricotta cheese from part-skim milk (1/2 cup) 335 mg
Soymilk, fortified (8 ounces) 300 mg
Spinach, cooked from frozen (1 cup) 290 mg
Milk, 2% milk fat (8 ounces) 285 mg
Swiss cheese, shredded (1/4 cup) 214 mg
Cheddar cheese, shredded (1/4 cup) 204 mg
Salmon, canned (3 ounces) 181 mg
Soybeans/edamame (1/2 cup) 130 mg
Tofu (3 ounces) 100 mg
Parmesan cheese, shredded (1 tablespoon) 55 mg
Spinach, cooked (1 cup) 230 mcg
Lentils, cooked (1/2 cup) 180 mcg
Papayas (1 medium) 116 mcg
Artichokes, cooked (1 medium) 107 mcg
Asparagus, boiled (4 spears) 89 mcg
Avocados (1/2 medium) 81 mcg
Raspberries (1 cup) 65 mcg
Black-eyed peas, canned (1/2 cup) 61 mcg
Red bell peppers (1 medium) 55 mcg
Oranges (1 medium) 39 mcg
Shiitake mushrooms, cooked (1/2 cup) 15mcg
Cereal
Total Raisin Bran (1 cup) 18 mg
Cheerios (1 cup) 9.5 mg
Spinach, cooked (1 cup) 6.4 mg
Oysters, raw (6 medium) 5.5 mg
Kidney beans, cooked (1/2 cup) 3.6 mg
Tomatoes, canned (1 cup) 3.4 mg
Lentils, cooked (1/2 cup) 3 mg
Ground beef, 85% lean (3 ounces) 2.2 mg
Lima beans, cooked from frozen (1/2 cup) 1.8 mg
Spinach, cooked (1 cup) 156 mg
Halibut, cooked (3 ounces) 91 mg
Cashews (1/4 cup) 89 mg
Oat-bran muffin (1 medium) 89 mg
White beans, canned (1/2 cup) 67 mg
Bran cereal (3/4 cup) 64 mg
Brown rice, cooked (3/4 cup) 63 mg
Potato, baked, with skin (1 medium) 57 mg
Whole-wheat bread (2 slices) 46 mg
Walnuts (1 ounce; 14 halves) 44 mg
Banana (1 medium) 32 mg
Potato, baked, with skin (1 medium) 1,082 mg
Sweet potato, baked, with skin (1 medium) 694 mg
White beans, canned (1/2 cup) 595 mg
Yogurt, low fat (8 ounces) 531 mg
Beets, cooked (1 cup) 519 mg
Halibut, cooked (3 ounces) 490 mg
Banana (1 medium) 422 mg
Kidney beans, canned (1/2 cup) 328 mg
Raisins (1.5-ounce box) 322 mg
Salmon, cooked (3 ounces) 319 mg
Blackberries (1 cup) 233 mg
Brazil nuts (1/2 ounce; 3–4 nuts) 270 mcg
Tuna, canned (3 ounces) 65 mcg
Couscous, cooked (1 cup) 43 mcg
Halibut, cooked (3 ounces) 40 mcg
Pasta, cooked (1 cup) 37 mcg
Pork (3 ounces) 30–40 mcg
Salmon, cooked (3 ounces) 32 mcg
Turkey or chicken, light meat (3 ounces) 24–27 mcg
Bagel (1 medium) 27 mcg
Ground beef, cooked (3 ounces) 18–24 mcg
Cereal
Total Raisin Bran (1 cup) 2.0 mg
Kellogg’s Special K (1 cup) 1.9 mg
Tuna, fresh, cooked (3 ounces) 0.9 mg
Potato, baked, with skin (1 medium) 0.6 mg
Chickpeas, canned (1/2 cup) 0.5 mg
Chicken breast, roasted, no skin (3 ounces) 0.5 mg
Banana (1 medium) 0.4 mg
Broccoli, boiled (1 cup) 0.3 mg
Sunflower seeds (1/4 cup) 0.2 mg
Tomato sauce, canned (1/2 cup) 0.1 mg
Carrots, raw (1 cup) 0.1 mg
Clams, canned (3 ounces) 84 mcg
Liver, calf’s, pan-fried (3 ounces) 70 mcg
Oysters, raw (6 medium) 16 mcg
Salmon, canned (3 ounces) 4 mcg
Tuna, light, canned in water (3 ounces) 2.5 mcg
Nutritional yeast (2 teaspoons) 2.5 mcg
Ground beef, 85% lean (3 ounces) 2 mcg
Lamb, loin chop (3 ounces) 2 mcg
Yogurt, plain, low-fat (8 ounces) 1.3 mcg
Cottage cheese, 2% milk fat (1/2 cup) 0.8 mcg
Peaches, frozen and sweetened (1 cup) 235 mg
Red bell pepper, raw (1 medium) 152 mg
Broccoli florets, cooked (1 cup) 101 mg
Strawberries (1 cup) 97 mg
Green bell pepper, raw (1 medium) 96 mg
Papaya (1 cup) 86 mg
Kiwifruit (1 medium) 70 mg
Orange (1 medium) 70 mg
Cantaloupe (1 cup) 59 mg
Mango (1 medium) 57 mg
Brussels sprouts, cooked (4 medium) 52 mg
Salmon, canned (3 ounces) 530 IU
Salmon, cooked (3.5 ounces) 240–360 IU
Tuna, canned (3 ounces) 200 IU
Soymilk, fortified (8 ounces) 100 IU
Orange juice, fortified (8 ounces) 100 IU
Milk, low-fat, fortified (8 ounces) 98 IU
Cereal, fortified (1 cup) 40–50 IU
Eggs (1 large) 20–26 IU
Swiss cheese (1 ounce) 12 IU
Cereal: raisin bran, corn flakes (1 cup) 20 IU
Almonds (1/4 cup) 14 IU
Sunflower seeds (1/4 cup) 12 IU
Spinach, cooked from frozen (1 cup) 10 IU
Hazelnuts (1/4 cup) 8 IU
Safflower oil (1 tablespoon) 7 IU
Red bell pepper (1 cup) 4 IU
Avocado (1/2 medium) 3 IU
Olive oil (1 tablespoon) 3 IU
Mango (1 medium) 3 IU
Tomatoes, canned (1 cup) 3 IU
Kale, cooked (1 cup) 1060 mcg
Spinach, cooked (1 cup) 888 mcg
Broccoli, cooked (1 cup) 220 mcg
Spinach, raw (1 cup) 150 mcg
Brussels sprouts, cooked (4 sprouts) 118 mcg
Okra, cooked (1 cup) 64 mcg
Lettuce, romaine (1 cup) 57 mcg
Asparagus (4 spears) 30 mcg
Kiwifruit (1 medium) 30 mcg
Blueberries (1 cup) 28 mcg
Oysters, raw (3 medium) 16–25 mg
Lamb chop (3 ounces) 6 mg
Ground beef, 85% lean (3 ounces) 5.3 mg
Ricotta cheese, part-skim milk (1 cup) 3.3 mg
Turkey, no skin (3 ounces) 2.6 mg
Kidney beans, canned (1/2 cup) 2 mg
Yogurt, plain, low-fat (8 ounces) 2 mg
Shiitake mushrooms (1 cup) 2 mg
Sunflower seeds (1/4 cup) 1.7 mg
Almonds (1/4 cup) 0.8 mg
Lycopene
Benefits
Lycopene is a carotenoid that may boost heart health, prevent vision loss, and lower the risk of some cancers.
RealAge Recommendation
There’s no specific RealAge recommendation for lycopene, but it’s found primarily in fruit, so eat 4 servings of fruit each day -- which can make your RealAge up to 4 years younger.
Good Sources
The brighter the better. Pink, orange, and red fruits are generally rich in lycopene. For a lycopene boost, consider:
• Watermelon
• Tomatoes, tomato juice, and tomato sauce
• Papaya
• Pink grapefruit
• Guava
Tip: It’s easier for your body to absorb lycopene from tomatoes that have been cooked, canned, or otherwise processed. Adding a little bit of fat helps as well, so cook your tomatoes with a splash of heart-healthy olive oil.
Vitamin E
Benefits
Vitamin E is an antioxidant that may help prevent heart disease, Alzheimer’s, and two common vision stealers -- macular degeneration and cataracts.
RealAge Recommendation
Government guidelines recommend a daily intake of 22.5 international units (IU) of vitamin E, but this is only enough to prevent deficiency. For optimal health and disease prevention, RealAge recommends that you aim for 400 international units (IU) of vitamin E per day. It’s tough to get all the E you need from food alone, so top up your supply with a daily supplement.
Tip: Take your E with C (1,200 mg). These two antioxidant vitamins work together to prevent the oxidation that causes clogs in blood vessel walls, and pairing them on a daily basis can make your RealAge 3 years younger.
Good Sources
Cereal: raisin bran, corn flakes (1 cup) 20 IU
Almonds (1/4 cup) 14 IU
Sunflower seeds (1/4 cup) 12 IU
Spinach, cooked from frozen (1 cup) 10 IU
Hazelnuts (1/4 cup) 8 IU
Safflower oil (1 tablespoon) 7 IU
Red bell pepper (1 cup) 4 IU
Avocado (1/2 medium) 3 IU
Olive oil (1 tablespoon) 3 IU
Mango (1 medium) 3 IU
Tomatoes, canned (1 cup) 3 IU
Vitamin K
Benefits
Your body uses vitamin K to help stop bleeding after a cut or injury. And K may also play a role in building strong bones, preventing osteoporosis, and reducing inflammation that leads to heart disease.
RealAge Recommendation
Shoot for at least 90 micrograms (mcg) of vitamin K per day for women and 120 mcg for men. Most people get enough K from their diets, but if it looks like you’re getting more than the recommended amount, not to worry: You can’t overdo vitamin K from fruits and vegetables.
One note: Significant changes in vitamin K levels can interfere with blood-thinning drugs (such as warfarin), so if you’re taking a blood thinner, talk to your doctor about being consistent with your K intake.
Good Sources
Leafy green vegetables have the highest amounts of vitamin K, but other fruits and veggies have good supplies, too:
Kale, cooked (1 cup) 1060 mcg
Spinach, cooked (1 cup) 888 mcg
Broccoli, cooked (1 cup) 220 mcg
Spinach, raw (1 cup) 150 mcg
Brussels sprouts, cooked (4 sprouts) 118 mcg
Okra, cooked (1 cup) 64 mcg
Lettuce, romaine (1 cup) 57 mcg
Asparagus (4 spears) 30 mcg
Kiwifruit (1 medium) 30 mcg
Blueberries (1 cup) 28 mcg
Vitamin A
Benefits
Vitamin A helps maintain healthy eyes, skin, teeth, and bones. It’s also essential for cell division -- which means renewal -- and it plays a key role in keeping your immune system strong.
RealAge Recommendation
Your body doesn’t need much vitamin A, and too much (in supplement form) can harm your health, so it’s best to get your A the natural way: from plenty of fruit and vegetables.
If you take a daily multivitamin, make sure it contains no more than 2,500–3,000 international units (IU) of vitamin A and that it’s in the form of beta carotene (from plants). Your body regulates its supply of plant-based A -- also known as provitamin A -- by absorbing it slowly and flushing out any excess before it becomes harmful. But other types of A -- from animal sources, such as liver and giblets, as well as some supplements -- can build up in your system and become toxic. You need to limit these types, called preformed or retinol A.
Bottom line: If you stick to fruit and vegetable sources and an appropriate multivitamin, you should be A-OK.
Good Sources
Eggs, milk, and fortified cereals are good sources of preformed vitamin A. For plant-based provitamin A, the following foods are your best bets. If you’re not taking a multivitamin with A, try to include at least one serving of these foods in your daily mix:
• Carrots
• Sweet potatoes
• Pumpkin and squash
• Red bell pepper
• Spinach
• Cantaloupe
• Mango
• Broccoli
Folate (Vitamin B9)
Benefits
Folate -- also called folic acid -- is a B vitamin that protects against arterial aging, aids in the production of red blood cells and DNA, and helps reduce levels of homocysteine (an amino acid that may raise your risk of heart disease).
RealAge Recommendation
Aim to get 700 micrograms (mcg) of folate per day. The average daily diet contains about 300 mcg, so choose a multivitamin with 400 mcg of folic acid to top up your daily dose. Pregnant women and people who have cancer, severe burns, or skin diseases may need extra folate to maintain healthy levels.
Don’t exceed 1,000 mcg of folate per day -- too much could lead to nerve damage or vitamin B12 deficiency.
Good Sources
Many pastas, breads, cereals, grains, and fruit juices produced in the U.S. are fortified with folic acid. Check labels for details. Other food sources include:
Spinach, cooked (1 cup) 230 mcg
Lentils, cooked (1/2 cup) 180 mcg
Papayas (1 medium) 116 mcg
Artichokes, cooked (1 medium) 107 mcg
Asparagus, boiled (4 spears) 89 mcg
Avocados (1/2 medium) 81 mcg
Raspberries (1 cup) 65 mcg
Black-eyed peas, canned (1/2 cup) 61 mcg
Red bell peppers (1 medium) 55 mcg
Oranges (1 medium) 39 mcg
Shiitake mushrooms, cooked (1/2 cup) 15mcg
Iron
Benefits
One of the primary functions of iron is to pick up oxygen in the lungs and deliver it to the rest of your body. Iron is also important for DNA synthesis, which promotes growth, healing, and a strong immune system.
RealAge Recommendation
We agree with the current government guidelines that recommend a daily iron intake of 8 milligrams (mg) for men and 18 mg for women. If you’re pregnant, increase your daily amount to 27 mg, and if you’re past menopause, reduce it to 8 mg.
Good Sources
It’s best to get your iron from food, so don’t use supplements unless you’ve been diagnosed with iron deficiency or are at risk for it and have been instructed by your doctor to do so.
Cereal
Total Raisin Bran (1 cup) 18 mg
Cheerios (1 cup) 9.5 mg
Spinach, cooked (1 cup) 6.4 mg
Oysters, raw (6 medium) 5.5 mg
Kidney beans, cooked (1/2 cup) 3.6 mg
Tomatoes, canned (1 cup) 3.4 mg
Lentils, cooked (1/2 cup) 3 mg
Ground beef, 85% lean (3 ounces) 2.2 mg
Lima beans, cooked from frozen (1/2 cup) 1.8 mg
Vitamin C
Benefits
Vitamin C helps your body metabolize proteins into energy, boosts your immune system, builds collagen in your skin, promotes healing, and aids in joint repair. It also helps keep your arteries young and prevents fatty plaque buildup on blood vessel walls. Wow!
RealAge Recommendation
To prevent vitamin C deficiency, government guidelines recommend a daily dose of 90 milligrams (mg) for men, 75 mg for women. RealAge recommends that you get 1,200 mg of vitamin C per day from food and supplements to make your RealAge as much as 1 year younger. This higher amount not only prevents deficiency but also helps prevent disease and needless aging.
Good Sources
Peaches, frozen and sweetened (1 cup) 235 mg
Red bell pepper, raw (1 medium) 152 mg
Broccoli florets, cooked (1 cup) 101 mg
Strawberries (1 cup) 97 mg
Green bell pepper, raw (1 medium) 96 mg
Papaya (1 cup) 86 mg
Kiwifruit (1 medium) 70 mg
Orange (1 medium) 70 mg
Cantaloupe (1 cup) 59 mg
Mango (1 medium) 57 mg
Brussels sprouts, cooked (4 medium) 52 mg
The Truth About Vitamin D
Get answers to commonly asked questions about vitamin D.
By Daniel J. DeNoon
WebMD Feature
Reviewed by Brunilda Nazario, MD
The hottest topic in medicine isn't the newest drug or the latest surgical device: It's vitamin D.
What brought the simmering debate to a boil was a 2007 study showing that people taking normal vitamin D supplements were 7% less likely to die than those who didn't take the daily supplements.
A year later, a major study found that when women with low vitamin D levels get breast cancer, they have a much higher chance of dying from their cancer than women with normal vitamin D levels.
That was surprising news. But just as surprising is the fact that many men, women, and children have insufficient blood levels of this important vitamin.
How many? Data suggest many of us don't get the vitamin D we need. For example, a 2007 study of childbearing women in the Northern U.S. found insufficient vitamin D levels in 54% of black women and in 42% of white women.
These findings led the American Academy of Pediatrics to double the recommended amount of vitamin D a child should take -- and have led many doctors to advise their adult patients to up their vitamin D intake.
Your health may depend on knowing the answers to these important questions:
• Why do I need vitamin D?
• How can I get enough vitamin D?
• Will a vitamin D test tell me if I need more vitamin D?
• Which foods contain vitamin D?
• How much vitamin D do my children and I need?
• Can I get too much vitamin D?
• What kind of vitamin D is best?
• Does vitamin D interact with other medications?
Why do I need vitamin D?
• Your body must have vitamin D to absorb calcium and promote bone growth. Too little vitamin D results in soft bones in children (rickets) and fragile, misshapen bones in adults (osteomalacia). You also need vitamin D for other important body functions.
• Vitamin D deficiency has now been linked to breast cancer, colon cancer, prostate cancer, heart disease, depression, weight gain, and other maladies. These studies show that people with higher levels of vitamin D have a lower risk of disease, although they do not definitively prove that lack of vitamin D causes disease -- or that vitamin D supplements would lower risk.
• The Vitamin D Council -- a scientist-led group promoting vitamin D deficiency awareness -- suggests vitamin D treatment might be found helpful in treating or preventing autism, autoimmune disease, cancer, chronic pain, depression, diabetes, heart disease, high bloodpressure, flu, neuromuscular diseases, and osteoporosis. However, there have been no definitive clinical trials.
• The best known benefit of vitamin D is its role in helping calcium build strong bones. But that's far from the whole story. Vitamin D helps regulate the immune system and the neuromuscular system. Vitamin D also plays major roles in the life cycle of human cells.
• Vitamin D is so important that your body makes it by itself -- but only after skin exposure to sufficient sunlight. This is a problem for people in northern climates. In the U.S., only people who live south of a line drawn from Los Angeles to Columbia, S.C., get enough sunlight for vitamin D production throughout the year.
• Dark skin absorbs less sunlight, so people with dark skin do not get as much vitamin D from sun exposure as do light-skinned people. This is a particular problem for African-Americans in the northern U.S.
How can I get enough vitamin D?
Thirty minutes of sun exposure to the face, legs, or back -- without sunscreen -- at least twice a week should give you plenty of vitamin D.
But this much direct sun exposure might also expose you to potentially dangerous levels of cancer-causing UV radiation. And unless you live in the South or Southwest, you probably won't get enough sunlight during the winter months for your body to make enough vitamin D. The American Academy of Dermatology recommends against getting vitamin D from unprotected exposure to sunlight.
It's probably a better idea to get vitamin D from foods or from supplements.
Will a vitamin D test tell me if I need more vitamin D?
Yes. As part of your regular blood test, your doctor should order a test for 25-hydroxyvitamin D (25-OHD).
Everyone agrees that anyone with a 25-OHD level of less than 15 ng/mL or 37.5 nmol/L (depending on the units reported by a lab) needs more vitamin D. A 2002 study found that 42% of African-American women of childbearing age had vitamin D levels below 15 ng/mL.
The U.S. National Institutes of health notes that 25-OHD levels over 30 ng/mL are optimal, and that there is "insufficient data" to support recommendations for higher levels.
The Vitamin D Council considers the ideal 25-OHD level to be between 40 ng/mL and 70 ng/mL.
Which foods contain vitamin D?
Surprisingly few foods contain vitamin D -- unless it's added to the food. That's because your body is built to get vitamin D through your skin (from sunlight) rather than through your mouth (by food). But once your body has enough, it doesn't matter whether you got it through your skin or through your stomach.
There are three vitamin D super foods:
• Salmon (especially wild-caught)
• Mackerel (especially wild-caught; eat up to 12 ounces a week of a variety of fish and shellfish that are low in mercury)
• Mushrooms exposed to ultraviolet light to increase vitamin D
Other food sources of vitamin D include:
• Cod liver oil (warning: cod liver oil is rich in vitamin A; too much may be bad for you)
• Tuna canned in water
• Sardines canned in oil
• Milk or yogurt -- regardless of whether it's whole, nonfat, or reduced fat -- fortified with vitamin D
• Beef or calf liver
• Egg yolks
• Cheese
Nearly all milk in the U.S. is fortified with vitamin D. So are many brands of orange juice, yogurt, margarine, and ready-to-eat breakfast cereals.
How much vitamin D do I need?
The current recommended daily dose of vitamin D is 200 IU for people up to age 50, 400 IU for people aged 51 to 70, and 600 IU for people over age 70.
That's not enough, Boston University vitamin D expert , MD, PhD, tells WebMD. Holick recommends a dose of 1,000 IU a day of vitamin D for both infants and adults -- unless they're getting plenty of safe sun exposure.
In 2008, the American Academy of Pediatrics recommended that breastfed infants receive 400 IU of vitamin D every day until they are weaned. This doubled the AAP's previous recommendation.
The AAP also recommends 400 IU/day of vitamin D for children and teens who drink less than a quart of vitamin D-fortified milk per day.
The Vitamin D Council recommends that healthy adults take 2,000 IU of vitamin D daily -- more if they get little or no sun exposure.
There's evidence that people with a lot of body fat need more vitamin D than lean people.
The Institute of Medicine's Food and Nutrition Board is currently updating its 1997 vitamin D recommendations. A report is scheduled for May 2010.
Can I get too much vitamin D?
Too much of any good thing is a bad thing. Too much vitamin D can cause an abnormally high blood calcium level, which could result in nausea, constipation, confusion, abnormal heart rhythm, and even kidney stones.
It's nearly impossible to get too much vitamin D from sunlight or from foods (unless you take way too much cod liver oil). Nearly all vitamin D overdoses come from supplements.
The Institute of Medicine's Food and Nutrition Board's 1997 recommendations -- scheduled for a May 2010 update -- suggest that 2,000 IU per day of vitamin D is safe for adults and that 1,000 IU per day is safe for infants up to 12 months of age.
However, the relatively small doses of vitamin D in daily vitamin pills are not enough to correct serious vitamin D deficiency. A 2009 study suggested that the best regimen for treating vitamin D insufficiency is 50,000 IU of vitamin D3 taken three times a week for six weeks. This time-limited regimen did not result in vitamin D toxicity.
How much vitamin D is too much? That's controversial. According to the National Institutes of Health, the maximum upper limit for vitamin D is 25 micrograms (1,000 IU) for children up to age 12 months and 50 micrograms (2,000 IU) for everyone else.
But some recent studies suggest that healthy adults can tolerate more than 10,000 IU of vitamin D per day. John Jacob Cannell, MD, executive director of The Vitamin D Council, notes that the skin makes 10,000 IU of vitamin D after 30 minutes of full-body sun exposure. He suggests that 10,000 IU of vitamin D is not toxic.
According to the National Institutes of Health, 25-OHD levels that are consistently over 200 ng/mL are "potentially toxic."
What kind of vitamin D is best?
The recommended form of vitamin D is vitamin D3 or cholecalciferol. This is the natural form of vitamin D that your body makes from sunlight. Supplements are made from the fat of lambs' wool.
However, a clinical study reported in 2008 suggested that vitamin D2 works as well as vitamin D3.
Many supplements contain vitamin D as vitamin D2 or calciferol. It's derived from irradiated fungus. Because this is not the form of vitamin D naturally made by your body, WebMD nutritionist Kathleen M. Zelman, MPH, RD, recommends using the D3 form for those taking vitamin D supplements.
Because of its potency, different forms of vitamin D are used in prescription medications. If you have a prescription for one of these medications, do not switch to another form of vitamin D without checking with your doctor.
Does vitamin D interact with other medications?
Yes. Steroid medications such as prednisone can interfere with vitamin D metabolism. If you take steroid drugs regularly, discuss vitamin D with your doctor.
The weight loss drug orlistat -- brand names include Xenical and Alli -- may cut absorption of vitamin D. So does the cholesterol-lowering drug cholestyramine (sold as Questran, LoCholest, and Prevalite). People taking these drugs should discuss vitamin intake with their doctors.
The seizure drugs Phenobarbital and Dilantin (phenytoin), affect vitamin D metabolism and affect calcium absorption. So do anti-tuberculosis drugs.
On the other hand, cholesterol-lowering statin drugs and thiazide diuretics increase vitamin D levels.
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