In the late 1800s a disfiguring and often fatal disease became epidemic in the South. Called pellagra (Italian for “rough skin”), it caused diarrhea, mental confusion, and severe scaling and flaking of the skin. By 1911, pellagra had become the leading cause of death in asylums. Eventually, the Public Health Service dispatched the physician Joseph Goldberger to determine its cause.
At the time, a “pellagra germ” was the leading suspect, but Goldberger dismissed this hypothesis after observing that the cases didn’t fit an infectious disease pattern. Pellagra was prevalent among people who depended on corn as a staple, and he proposed a dietary cause.
Goldberger became so sure of his theory that he hosted “filth parties” where he and a few of his medical colleagues downed pills filled with urine, feces and dried skin flakes taken from people with pellagra to prove that the disease was not contagious. Despite such experiments (which sickened none of the participants), scientists and politicians remained unconvinced.
It wasn’t until 1937 — eight years after Goldberger’s death — that niacin, or vitamin B3, was isolated and identified as the cure. Diets reliant on corn make people susceptible to a deficiency of niacin.
Catherine Price recounts the story of how science cracked the pellagra mystery in “Vitamania,” (Read an excerpt.) her absorbing and meticulously researched history of the beginnings and causes of our obsession with vitamins and nutrition. After more than a century of research, “Scientists still don’t fully understand all the nuances of what vitamins do in our bodies, how they do it, or what the long-term effects of moderate deficiencies might be,” she writes.
Once thing is certain: No matter how poor your diet, it is virtually impossible to become truly vitamin-deficient in the United States these days, Ms. Price says, because our processed foods are so universally enriched and fortified with synthetic vitamins. The majority of these additives are manufactured in China, and without them, much of our food would be devoid of nutritional value.
Vitamins are typically flavorless and invisible, so we depend on experts and product labels to tell us which ones are contained in an item and which foods we should consider healthy. Our dependence on labels “has primed us to accept the amazing array of health claims, advertisements and advice that we encounter each day,” Ms. Price writes.
We eagerly gobble up foods claiming that added vitamins and dietary chemicals will “support a healthy metabolism,” but few stop to ask what that means or how it has been proved: “As long as advertisements employ the magic word science, we are willing to accept claims that otherwise might crack under the pressure of common sense.”
On a trip to her local GNC store, Ms. Price finds Natural Curves, a product that promises to deliver “natural bust enhancement” with a “100% natural” “balanced formula for maximum results.”
A search of the medical literature turns up no evidence that the proprietary blend of herbs listed on the bottle could make good on the product’s promises. Nor are there rigorous studies to support claims made by a sea buckthorn product to soothe the author’s sensitive skin.
Despite the paucity of evidence, even medical experts can fall into marketing traps. Ms. Price’s physical therapist is flabbergasted when she tells him that his favorite supplement pills aren’t approved by the Food and Drug Administration, and he is not alone.
A study in 2007 found that a third of doctors didn’t know that dietary supplements aren’t subject to F.D.A. approval or safety testing. Given the lack of oversight, it is not terribly surprising that a recent investigation by the New York attorney general’s office found that a large number of the herbal supplements on store shelves did not contain the ingredients listed on the label.
Several incidents have highlighted a need for greater oversight: In the 1990s, contaminated L-tryptophan supplements killed 40 people and harmed more than 1,550 others. But even toothless regulatory proposals have met fierce pushback from the supplements industry.
An amendment to the Federal Food, Drug and Cosmetic Act in 1976 prohibits the F.D.A. from limiting the potency of vitamins and minerals or regulating them as drugs. The Dietary Supplement Health and Education Act of 1994 helped ensure that supplement makers would not be required to demonstrate that their products were safe or effective.
When the F.D.A. attempted to ban unsubstantiated claims from supplement labels, a trade group called the National Health Alliance organized a huge — and, Ms. Price argues, deceptive — letter-writing campaign, despite the fact that the proposed rules would have regulated only the labels, not the products themselves.
The campaign enlisted employees and customers of 10,000 or so health food stores to write Congress. An estimated two million letters were sent.
Ms. Price understands why. Doctors she had seen for her skin problem couldn’t agree on a diagnosis, “let alone a treatment,” she writes. The promises made on the sea buckthorn packaging, by contrast, were confident and comforting.
What supplement peddlers are really selling is hope, Ms. Price argues — a counter to the uncertainty that so often accompanies real science.
- http://bit.ly/17LjAYH
Niciun comentariu:
Trimiteți un comentariu