Could supplements replace food as the main nutrient source?

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Related tags: Supplements, Nutrition

The general population should rely on diet for its nutrient needs
and not view supplementation as an insurance policy against
imperfect diet, according to an article published today in the
Journal of the American Medical Association. But Jess
Halliday asks: did anybody really think replacing food with
supplements was a sensible idea anyway?

Tuft University co-authors Alice Lichtenstein and Robert Russell say that there is "insufficient data to justify an alteration in public health policy from one that emphasizes a food-based diet to fulfill nutrient requirements and promote optimal health outcomes to one that emphasizes dietary supplementation."

But who, may we ask, is asking for supplements to replace foods?

Not the food industry, that's for sure.

Nor the American Dietetic Association, which maintains that a sensible, balanced diet should be the primary source of nutrients.

Nor the industry associations such as the National Nutritional Foods Association and the Council for Responsible Nutrition (CRN), which see supplements as a bridge across the gap created by most people's inability to meet recommended daily intake of nutrients through diet alone.

"Diet or supplements is a question that shouldn't be posed,"​ Dr Andrew Shao, CRN's VP scientific and regulatory affairs told "The emphasis should be on both, not either/or. We are confused as to why the authors ask the question in the first place."

The authors of the special communication base their conclusion on studies into nutrition and optimal health. While the most promising data on nutrition and optimal health has come from epidemiological studies relating to dietary patterns, they say that when investigative studies have been carried out using high doses of single nutrients or nutrient cocktails, the results have been disappointing.

In particular, they draw attention to intervention studies seeking to validate the epidemiologically-observed link between vitamin E and cardiovascular disease, and beta-carotene and lung cancer.

"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,"​ said Lichtenstein.

But Shao's opinion is that the authors are taking the science out of context.

"These clinical trials are set up in the name of scientific process, designed to answer a specific question not to influence public opinion with the goal of people relying on supplements for their nutrients,"​ he said.

He also drew attention to randomized clinical studies where the observed benefits of supplementation have been positive, saying their omission means the report is "unbalanced"​. These include calcium and vitamin D for bone fractures, omega 3 and heart disease, glucosamine and chrondroitin and osteoarthritis.

As to the authors' concern that shifting public health policy from food to supplements would encourage people to see supplements as an 'insurance policy' against an imperfect diet, to what extent is that already the case?

Certainly taking a multivitamin each day is seen as "insurance policy"​ against not achieving recommended daily intakes of all nutrients. But Shao says that the analogy is misleadingly portrayed in the article, which presents the idea of supplements as insurance against a glutinous lifestyle.

"If the idea is to focus on diet, how come there is no mention of junk food and increased portion sizes?"

Like all chemicals, however, nutrients can interact with each other. Examples given by the article include iron inhibiting zinc absorption, zinc inhibiting copper absorption and vitamin E interfering with the action of vitamin K. In supplements, beta carotene can inhibit lutein absorption, but in genetically selected yellow carrots the two can occur together with no effect.

This is an important issue, according to the report, because of the recommendation by some that nutrient supplements be used by the general population, and the trend towards the unregulated addition of nutrients to foodstuffs that would not ordinarily contain them.

What is more, the over-fortification of food products has, in a few cases, led to nutrient toxication - such as too much niacin added to pumpernickel bagels and vitamin D to milk.

It is a stark warning, and one that might give leverage to some parties calling for tighter controls on supplements than the Dietary Supplements Health and Education Act (DSHEA) can provide.

Shao said that this was possible. But nutrient interactions from supplements are just one aspect of a subject that needs further investigation. Interactions occur in the diet too - at food level, at functional food level and at supplement level.

"It should be the focus of more research,"​ he said.

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