The DRI Debate

posted by Victoria Clayton
filed under diet postings

Whether you're concerned with your diet or just bored at the breakfast table, you probably already realize that the "Nutrition Facts" on food labels provide interesting information—if you're a human calculator. Unless you keep track of what you've eaten and what percentage of which nutrient you might lack (and therefore need to eat later in the day), the information beyond calories, fat, and serving sizes may seem esoteric. Even so, the info—called Daily Values or DVs—is vital to your health, since it compares the levels of nutrients in the food item to the total amount of the nutrient you're likely to need for the day. And now the Food and Nutrition Board (FNB) of the National Academy of Sciences is gradually introducing a new standard called the Dietary Reference Intake (DRI). DRI is a general term for different ratings that will apply to vitamins, minerals, and proteins (though you probably won't see them on food labels for a few years).

Why the new rules? According to Allison A. Yates, Ph.D., R.D., director of the Food and Nutrition Board, DRIs are more thorough. In addition to offering recommended nutrient levels to stave off deficiency diseases (the underlying reasoning behind the current DVs), they give recommendations for levels that scientific data concludes should improve your health—amounts that many scientists say help fight cancer, cardiovascular disease, osteoporosis, and potential birth defects, among others.

To formulate these new recommendations, panels of Canadian and U.S. researchers extensively reviewed and analyzed nutritional studies. In some instances, the panels found that ranges higher than the current DVs of key vitamins are warranted. For example, adequate intakes of calcium have been thought to prevent osteoporosis. But the FNB panel concluded that the 800 mg to 1,000 mg DV range, which was once thought to be plenty, is not. "The previous high recommendation was one thousand milligrams for adolescents, but now we're looking at thirteen hundred for adolescents and twelve hundred for adults," says Yates.

The DRIs have also bumped up the recommended level of folic acid, which is now thought to prevent heart disease as well as neural tube defects in fetuses. According to the FNB, all women should get 400 micrograms (mcgs) daily, and pregnant women should get 600 mcgs daily rather than the previously recommended 180 and 400 mcgs. The DRI for vitamin C has also been increased from 60 mg to 75 mg for women and 90 mg for men (smokers should take 35 mg more); and vitamin E to 22 I.U. (up from 12 I.U. for women and 15 for men).

And for the first time, the Institute has set "upper limits," defined as the highest level likely to be safe for most people. For example, the upper limit for vitamin C is 2,000 mg a day (more than this can cause diarrhea); the upper limit for vitamin E is 1,500 I.U. of alpha-tocopherol, or natural vitamin E (more could interfere with blood coagulation).

Some believe the recommended amounts should be higher. "The DRIs are still too conservative," according to Earl Mindell, Ph.D., author of The Vitamin Bible, who says that government recommendations for nutrients are too carefully weighed against economic consequences. "People have to realize that the reason the government is so conservative is that these recommendations affect the military, school lunch programs, prisons, and other programs. If it raises a nutrient a half a milligram, all of these programs might have to meet the new minimum. That's expensive." Again, the DRI recommendations do not immediately affect Daily Values (the information found on food labels that does determine government programs), but there is a consensus that they will eventually. Mindell recommends eating or supplementing to 500 mg to 1,000 mg of vitamin C and 400 to 500 I.U. of vitamin E. Even though Mindell's recommendations for these two antioxidants are extremely high, according to the American Dietetic Association (ADA) and the FNB, you would have to take roughly 25 times the recommended intake of these two particular nutrients to run a risk of toxicity.

While everyone agrees that we should eat more nutritious whole, unprocessed foods, the issue of supplementation is controversial; Yates, for one, is against it. She warns that with the FNB panels, judgments are made based on getting the nutrients through food instead of supplements. In fact, supplements might not work the way food does, she says. "There are a lot of substances in food that play a role. Some of the substances have yet to be discovered and quantified."

A multivitamin should just be used as an insurance policy," adds Connie Diekman, R.D., a spokesperson for the ADA. "If you're not sure whether you are getting all of the recommended amounts of vitamins and minerals in your diet, you can take a multivitamin." (Strict vegans and pregnant women also are exceptions, since most everyone agrees they should take supplements.)

DRI reports have been released on calcium, vitamin D, B vitamins (including folic acid), and antioxidants. A report on trace elements and vitamins A and K is due out this month. To view these reports, go The Food and Nutrition Board at the web site of The National Academies Institute of Medicine.

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