B vitamins take aim at Alzheimer's, cancer, heart attack, stroke.
Here, EN reveals the latest research and tells you what you need to know to get an A+ in the B's.
B Basics. The complete B family of vitamins includes thiamin (B1), riboflavin (B2), niacin (B3), pyridoxine (B6), cobalamin (B12), folate, pantothenic acid and biotin.
What unifies the B vitamins? All help produce energy from carbohydrates, fats and proteins in the food we eat, as well as help produce DNA and new cells (especially red blood cells). All are required for a healthy brain, nerves, muscles and heart.
Each B has a different job, yet in the body they work in concert. This interdependence often influences their ability to function, as in the case of folate, which requires B12, and as with niacin, which needs riboflavin and vitamin B6. The key is to get a good balance of all the B vitamins.
Link to Chronic Diseases. Perhaps the greatest evidence that the sum of the B's is greater than each one individually is their action on homocysteine. High blood levels of homocysteine are directly related to increased risk of heart disease, stroke, dementia, Alzheimer's and some cancers. Past research shows that folate has a strong ability to lower homocysteine levels. However, while the recent addition of folate to enriched products has improved blood folate levels, homocysteine levels have dropped only a little.
"We now know that folate together with B6 and B12 lowers homocysteine levels better than any one B vitamin by itself," says Katherine Tucker, Ph.D., nutrition epidemiologist at Tufts University in Boston. "We also know that people's blood levels of B12 are lower than we thought."
A recent government study found that nearly 40% of 3,000 adults surveyed had B12 levels in the "low normal" range, despite eating foods rich in B12. That could explain why homocysteine levels have fallen little with folate fortification; they may have needed more help from B12.
Scientists are now taking a closer look at how B vitamins' ability to lower homocysteine can improve health.
Alzheimer's Angle and Cognitive Clues. An ambitious three-year intervention study called VITAL (VITamins to slow ALzheimer's disease) is looking at whether the combination of B6, B12 and folate can help slow the progression of Alzheimer's disease.
"We know that people with Alzheimer's tend to have high blood levels of homocysteine. And the higher the homocysteine, the greater the brain damage," says Paul Aisen, M.D., of Georgetown University, lead researcher. "Our goal is to find out if lowering homocysteine with B vitamins will help."
Low B12 levels are also being studied for other possible adverse effects on the brain in the long term.
"We think slow, progressive B12 deficiency may be related to some of the mental and neurological problems we see with aging," says Tucker. "This is something specific to B12, above and beyond the homocysteine issue."
A Case Against Cancer. Another area of research on B vitamins--specifically folate and B6--is the battle against cancer. Both vitamins are crucial for the normal production and repair of DNA, our body's genetic code. When there is inadequate folate or B6, scientists believe the resulting DNA is more prone to damage or breaks, which allow cancer cells to develop.
Data from the Nurses' Health Study suggest that folate intake may help protect women with a family history of colon cancer. Compared to the women with low intakes of folate, women with high intakes halved their risk of colon cancer. There is a similar link with breast cancer.
As for B6, several population studies have found that people with higher intakes were less likely to develop several kinds of cancers than people who took in lower amounts.
Heart Disease and Stroke. B's link to homocysteine was first fueled by the heart disease connection, noted decades ago. An inadequate intake of folate and vitamins B6 and B12 is known to raise homocysteine, a risk factor for heart disease. While getting enough of the key B vitamins is not likely to eliminate cardiovascular disease, which also includes stroke, most experts believe it is important to risk reduction.
Getting Your B's. Which B's are in short supply? How to get enough? Getting adequate thiamin and niacin is rarely an issue, thanks to enriched grains. Pantothenic acid and biotin are even less of a worry. But while intake of folate is improving, it's still not optimal. Many people also come up short on B2, B12 and possibly B6.
Most B vitamins are found in animal products like meat, turkey, milk, cheese and eggs, but if you're not a big carnivore, not to worry; plenty of B's--though, notably, not B12--are found in legumes, whole grains and even some fresh fruits and vegetables. Fortified foods like cereals are good choices, though not all the B's are added.
Older people, vegetarians and anyone who eschews red meat and milk are at higher risk for inadequate intake of several B's, especially B12 and riboflavin (B2). Nutrition scientists like Tucker predict B12 will be the next nutrient added to "enriched" grains. In the meantime, it's clear that you should take a daily multi, at the least.
"Stress" levels of B vitamins are not needed. Look for a supplement with about 100% of the Daily Value for all but pantothenic acid and biotin, which are unlikely to run short. Getting somewhat more of B6 and B12 (as in Centrum Silver or a similar substitute) is a good idea for those over 50. Avoid individual supplements of B6, which is toxic to nerves at high levels. And too much folate can hide the symptoms of a B12 deficiency. For more about the B's, see EN's guide, left.
EN's Guide to B Vitamin Basics B Vitamin Functions Daily Needs Thiamin Helps convert sugars to energy; Men: 1.2 mg (B1) essential for healthy brain, Women: 1.1 mg nerve, heart and muscle function. Riboflavin Helps convert sugars to energy; Men: 1.3 mg (B2) aids enzyme reactions; boosts Women: 1.1 mg uptake of iron; necessary for healthy skin, eyes and GI tract. Niacin Helps metabolize carbohydrate, Men: 16 mg (B3) fat and alcohol; maintains skin, Women: 14 mg nerves and GI tract; lowers blood cholesterol (in Rx doses). Vitamin B6 Aids protein metabolism; needed to 50yrs: 1.3 mg (pyridoxine) for healthy function of brain, 50+ Men: 1.7 mg nerves and immune system. 50+ Women: 1.5 mg Vitamin B12 Helps build healthy red blood All adults: (cobalamin) cells, nerve cells and bone cells; 2.4 mcg converts folate to active form. Folate Aids cell reproduction and All adults: 400 mcg (folic acid, growth, healthy red blood cells (recommend 200 folacin) and DNA synthesis. mcg as folic acid in supplements) Pantothenic Helps metabolize carbohydrate, All adults: 5 mg Acid fat and protein. Biotin Helps metabolize carbohydrate, All adults: 30 mcg fat and protein. B Vitamin Food Sources Thiamin Pork, fortified cereals, split (B1) peas, brown rice, whole wheat, enriched grains. Riboflavin Milk, yogurt, eggs, cheese, (B2) liver, beef, chicken, fish, enriched grains, fortified cereals. Niacin Beef, tuna, chicken, peanut (B3) butter, enriched grains, fortified cereals. Vitamin B6 Bananas, beans, broccoli, (pyridoxine) whole grains, potatoes, poultry, red meat, fish, chickpeas. Vitamin B12 Animal products: milk, (cobalamin) eggs, cheese, meat, poultry, fish plus fortified cereals and fortified soy milk. Folate Beans and peas, beets, (folic acid, kale, broccoli, lentils, okra, folacin) asparagus, turnip greens, spinach, oranges, enriched grains, fortified cereals. Pantothenic Widely available in many Acid foods. Biotin Egg yolks, yeast, liver, pork, cereal, chocolate. mg = milligrams mcg = micrograms [c] Copyright, 2003 by Environmental Nutrition, Inc.
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|Date:||Aug 1, 2003|
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