Revamping RDAs : Remember the chart that tells how much of this and that you should eat? Most agree it needs rewriting. But how?
The ‘90s have been good for nutrition research.
Scientists have shown us that doses of Vitamin C-- five or six times the recommended daily allowance--may slash the risk of several forms of cancer.
Doses of Vitamin E--many times the RDA--help cut the risk of heart disease.
Doubling the RDA for folic acid in reproductive-age women can dramatically reduce a certain type of birth defect.
And if teen-age girls consume lots more calcium, they might well avoid osteoporosis later in life.
All of which raises the question: What’s wrong with the RDAs?
That minutiae-filled table of numbers and nutrients that was cast on paper almost 60 years ago is the subject of a lot of soul-searching these days among the people who set nutrition policy in the United States.
Almost everyone agrees that it’s time to revamp the RDAs--which is normally done about every five to 10 years, and was last done in 1989--but there is no money to fund the project and no consensus about how to do it should the money suddenly appear. And that bothers a lot of people who worry that the recent knowledge surge will have little benefit unless the RDAs reflect what is known.
“The whole premise behind the RDAs is that at least every decade, we should take stock in what our research findings are,” says Gail C. Frank, a nutrition professor at California State University, Long Beach. “These are not like the Ten Commandments and they never change. These are supposed to be evolutionary.”
*
In the Washington-based offices of the Food and Nutrition Board, the branch of the National Academy of Sciences responsible for the RDAs, officials are pondering what would essentially be a revolutionary change in the document.
RDAs were established in 1941 at the request of the War Department. Military leaders wanted to know what to put in rations and how to beef up the many malnourished enlistees, says Allison Yates, executive director of the Food and Nutrition Board.
Eventually, use of the RDAs was expanded to reflect the amount of a nutrient needed to help all segments of the population avoid deficiencies. Diseases such as rickets and scurvy began to fade.
But, says Yates: “For the last 20 years, more and more research has been devoted to the effects of nutrients on developing chronic diseases, such as cardiovascular disease and cancer. We need to think hard about how to [set RDAs] in the future as we get more sophisticated.”
Many nutrition experts are eager to see a new set of RDAs that would have more impact on reducing the chronic diseases that kill so many Americans.
Nevertheless, there are nutritionists who fear that changing the RDAs to help prevent chronic disease will allow the document to be overtaken by special-interest groups and will lead consumers to falsely believe that they are not getting enough of certain nutrients.
For example, not everyone is at high risk of heart disease and, thus, would not need a drastic increase in Vitamin E, says Dr. Mark S. Meskin, director of the nutrition program at the USC School of Medicine.
“If you believe people with high levels of low-density lipoprotein cholesterol [a risk factor in heart disease] would benefit from extra Vitamin E, that’s OK. But someone with low levels of low-density cholesterol doesn’t need it.
“Incorporating higher levels in the RDAs is going to suggest that virtually everyone is deficient,” he says.
Meskin says a better approach would be to leave the RDAs as they are and allow doctors and nutritionists to prescribe extra nutrients to high-risk people who might benefit from them.
“We shouldn’t be micro-managing with the RDAs,” he says. “The fact that there are therapeutic possibilities of many vitamins doesn’t mean we should provide enough for every person for every therapeutic possibility.”
Increasing the RDAs even for some groups--the document lists the allowances for various age and gender groups--might cause problems for other population groups, Meskin says.
For example, there is a concern over iron deficiency in women and children, which causes anemia. But about 10% of the population carry a gene that puts them at risk for iron overload. In one study, too much iron has been linked to heart disease, Meskin says.
“If we push supplements [with more iron] or fortified more foods with iron, we could actually see more cases of iron overload,” he says. “Men for most of their adult years, for example, don’t need more iron.”
Some nutritionists also express concern that a dramatic increase in certain nutrient RDA levels might lead people to take supplements and ignore their overall diet.
“We may risk going to extremes because there are advocates of certain vitamins and minerals who say that these numbers should be off the wall, that people should self-prescribe and buy single nutrients off the shelf,” Frank says. “That’s a fallacy. Good nutrition is not about meeting the RDA for every single nutrient. Good nutrition is the composite of what people select.”
Indeed, many experts suggest that consumers ignore the RDAs and use other nutritional guides, such as the new food labels, which list information on sodium, fat, cholesterol, calories and fiber--problem areas for many Americans.
Another consumer guide is the Food Guide Pyramid, which tells how many servings are needed from the major food groups to have a diet of 60% carbohydrates, 30% fat and 10% protein. This guide is similar to the old Four Food Groups chart, but de-emphasizes meats in favor of more rice, pasta, grains, fruits and vegetables.
But people at risk for heart disease, colon cancer or osteoporosis--if they follow the Food Guide Pyramid--would miss out on the opportunity to lower their chances through big doses of certain nutrients, says Annette Dickinson, director of scientific and regulatory affairs for the Council for Responsible Nutrition, a Washington-based association of the nutrition supplement industry.
“The [Vitamin E] studies indicated that subjects only had this protective effect if they took 100 International Units a day . . . levels that are many times the RDA. This is an amount one could only take in supplements,” Dickinson says.
Moreover, she says, although the Food and Nutrition Board has indicated a desire to alter the intent of the RDAs, “it’s not clear that they would be translated into numbers or a range of intake” high enough to prevent disease.
A compromise among the warring factions of nutrition experts may be in the offing, however. While no formal decisions have been reached, the next RDAs may be presented in a more complex format that gives consumers a range of allowances, from what is adequate to prevent deficiency to what is needed to prevent disease and is still safe.
The next RDAs may also look at non-nutrient food components such as cholesterol, transfatty acids and phytoestrogens--all components that have an effect on health. It may also suggest how much of a nutrient can be obtained through food as compared to a supplement. Finally, it may create more categories for people older than 50.
Everyone agrees that hashing out new allowances under this format will be time-consuming and complicated.
“It’s an extraordinarily complex process, and it becomes more complex with each go-around,” Meskin says. “I have a concern that it’s becoming a very politicized document. Various nutrition groups stand to gain or lose depending on how they push the document. Scientists, [consumer organizations], birth defects organizations and everyone are throwing in their two cents. The 10th edition [in 1989] came out very late because it had become a political football.”
Changing the RDAs with little money and lots of controversy may also mean that the next edition will be released in increments. For example, with a clear need to address prevention of osteoporosis, the Food and Nutrition Board has proposed as its first evaluation the nutrients related to bones: calcium, magnesium, Vitamin D and phosphorus.
And, instead of one oversight committee, various panels will be formed to look at particular nutrients, Yates says. The panels will make recommendations to the oversight board. From there, another review committee would approve any changes.
“A lot of processes are set in place to prevent one group from having an inordinate amount of influence,” Yates says. “Hopefully, if there is anything that isn’t substantiated by science, it will be identified.”
(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)
Make It Count
The Recommended Dietary Allowances (RDAs) for 11 vitamins, seven minerals and protein were last revised in 1989. Since then, some nutritionists have called for an overhaul that would dramatically change how the decades-old document is used. Some of the controversy surrounding three of the vitamins includes.
*
Vitamin E: Several studies show that taking daily doses more than seven times the current RDA results in a 40% decreased risk of heart disease.
*
Vitamin C: Studies show that 380 milligrams (six times the current RDA) could help reduce breast cancer by as much as 16%. Doses of 250 to 500 milligrams might also help reduce the risk of several other cancers.
*
Folic acid: According to the U.S. Department of Health and Human Services, more than doubling the RDA for women in their reproductive years could help reduce neural tube birth defects by at least half.
*--*
Vit. E(mg.) Vit. C(mg.) Folic acid(mcg.) Infants birth to 6 months 3 30 25 Infants 6-12 months 4 35 35 Children 1-3 years 6 40 50 Children 4-6 7 45 75 Children 7-10 7 45 100 Males 11-14 10 50 150 Males 15-18 10 60 200 Males 19-24 10 60 200 Males 25-50 10 60 200 Males 51 and older 10 60 200 Females 11-14 8 50 150 Females 15-18 8 60 180 Females 19-24 8 60 180 Females 25-50 8 60 180 Females 51 and older 8 60 180 Pregnant 10 70 400 Lactating, first six months 12 95 280 Lactating, second six months 11 90 260
*--*
Preventing Osteoporosis
Experts are so concerned about the low intake of calcium among Amerians that, in 1994, the National Institutes of Health released a statement advising consumers of the optimal calcium intake needed to prevent osteoporosis. In most cases, these levels are well above the current RDAs.
*
Infants birth to 6 months
RDA: 400 (Measured in milligrams)
NIH: 400 (Measured in milligrams)
*
Infants 6-12 months
RDA: 600
NIH: 600
*
Children 1-10 years
RDA: 800
NIH: 800-1,200
*
Children, young adults 11-24
RDA: 1,200
NIH: 1,200-1,500
*
Adult men 25-64
RDA: 800
NIH: 1,000
*
Adult men 65 and older
RDA: 800
NIH: 1,500
*
Adult women 25-49
RDA: 800
NIH: 1,000
*
Adult women 50-64
RDA: 800
NIH: 1,000 if taking estrogen; 1,500 if not taking estrogen
*
Adult women 65 and older
RDA: 800
NIH: 1,500
*
Pregnant and lactating women
RDA: 1,200
NIH: 1,200-1,500
