It is premature to focus on nutrient supplements over diet

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It is premature to focus on nutrient supplements over diet

21 Jul 2005 Medical News Today

In a special communication piece that appears in the July 20th issue

of the Journal of the American Medical Association (JAMA), Alice

Lichtenstein, DSc, senior scientist and director of the

Cardiovascular Nutrition Laboratory at the Mayer U.S. Department

of Agriculture (USDA) Human Nutrition Research Center on Aging at

Tufts University and the Center's director and senior scientist,

, MD, report that the most promising data on nutrition

and optimal health outcomes relate to dietary patterns, not nutrient

supplements. They further state that there are insufficient data to

justify altering public health policy from an emphasis on foods and

dietary patterns to one on supplements.

The authors emphasize that nutrient supplementation, particularly for

certain at-risk populations, has an important place in health care.

However, they point out that there is an important difference between

observing associations between particular nutrients and health

outcomes and detecting causal connections.

" Perhaps no better example exists than the disheartening results of

the vitamin E intervention trials for the prevention of

cardiovascular disease, " says . Lichtenstein explains that

although observational studies suggest positive effects, " we lack

supporting evidence from intervention trials, and that is critical

for making recommendations to the public. "

Data are insufficient in other areas as well, according to

Lichtenstein. " Disease-nutrient relationships are by their nature

very complex. Within the context of high dose nutrient

supplementation, outcomes are frequently unexpected. Not only have

some studies failed to yield positive results but, occasionally

unanticipated negative effects have been observed. "

The authors point out that some of the unanticipated findings from

high dose single or nutrient cocktails may be because the levels used

are much higher than those necessary to prevent deficiency disease.

In one study, adding a nutrient antioxidant cocktail to a well

established cholesterol-lowering drug treatment actually lessened the

beneficial effect. " We still have a lot to learn about the use of

high doses of nutrients. The important point is to prevent the cart

from getting in front of the horse; we need to validate the science

before there is wide scale adoption by the general public as we saw

with vitamin E. We can no longer automatically assume there will be

no adverse consequences, " notes Lichtenstein.

In their overview of the existing literature, Lichtenstein and

, both professors at Tufts University's Friedman School of

Nutrition Science and Policy and School of Medicine note that their

caution is " based on the lack of a complete understanding of nutrient

requirements and interactions, and disappointing results of

intervention studies with single nutrients or nutrient cocktails. "

" The identification, isolation, and purification of nutrients in the

early 20th century raised the possibility that optimal health

outcomes could be realized through nutrient supplementation, " write

the authors, but this advance has been " a double-edged sword. "

While the current expert opinion is that there is not enough evidence

to justify emphasizing nutrient supplements instead of food and diet

for maintaining good health, this topic remains under rigorous

research, and new data is published regularly. Based on the available

information, the authors say, " eat a diet rich in fruits, vegetables,

low-fat dairy products, whole grains and fish. "

The Gerald J. and Dorothy R. Friedman School of Nutrition Science and

Policy at Tufts University is the only independent school of

nutrition in the United States. The School's eight centers, which

focus on questions relating to famine, hunger, poverty, and

communications, are renowned for the application of scientific

research to national and international policy. For more than two

decades, the Mayer USDA Human Nutrition Research Center on Aging

at Tufts University has studied the relationship between good

nutrition and good health in aging populations. Tufts research

scientists work with federal agencies to establish the US Dietary

Guidelines, the Dietary Reference Intakes, and other significant

public policies.

Tufts University

http://www.tufts.edu