November 6, 2012

Supplements Update, #1: More Fail the Test

More than half of us take dietary supplements and spend nearly $30 billion a year on them. But scientific studies continue to find little support for the claims that they truly help us. Back in February, I did a series of posts about the most popular supplements. Here's a link to the last post in that series; you can work your way back from there -- http://bit.ly/whYrES.

Since then, I've continued to follow reports on new studies. As a distraction from the tidal wave of election news the last few days, I've decided to do an update on supplement developments since February. As usual, most of the reports concern supplements that -- when tested -- failed to live up to their hype.

Here's a rundown:

Supplements To Fight Cancer
A review of the scientific evidence for the National  Cancer Institute found little support for marketing dietary supplements as protection against cancer. That evidence suggested that high doses of some supplements can actually increase cancer risks.

Most clinical trials of vitamin and mineral supplements as cancer fighters have disappointed, the reviewers concluded. Except for a lone Chinese study, trials of antioxidant supplements -- including beta carotene, vitamins C and E -- failed to show anti-cancer benefits. Results for long-term folic supplements have also been mostly negative.

Although some epidemiological studies have linked higher vitamin D levels to lower rates of certain cancers, the review found the evidence insufficient and called for more research.

Despite the absence of evidence that supplements prevent cancer -- and in light of suggestions that they may actually cause harm -- reviewers noted that "marketing claims by the supplement industry continue to imply anti-cancer benefits." They blamed "insufficient government regulation" of the $30 billion-a-year industry.

Caveat: As I noted in a recent post, curcumin, the active ingredient in the Indian spice turmeric, has been shown in many peer-reviewed studies to have cancer-treating potential. It wasn't covered in the NCI study, since it is not heavily marketed.

Omega-3 Fatty Acid Supplements
In a study that included nearly 70,000 patients, supplementation with omega-3 polyunsaturated fatty acids was not associated with a lower risk of cardiac death, sudden death, heart attack, or stroke. The analysis, published in the September 12, 2012 issue of the Journal of American Medicine, reviewed many previous studies. The authors concluded:
Our findings do not justify the use of omega-3 as a structured intervention in everyday clinical practice or guidelines supporting dietary omega-3 PUFA administration.
A similar conclusion was reached in a study that included 12,536 people with diabetes or pre-diabetes and additional cardiovascular risk factors who received either omega-3 fatty acids or a placebo. The study was published in the New England Journal of Medicine.

ORAC: Oxygen Radical Absorbance Capacity
ORAC: Over-Rated Antioxidant Claims
That first definition of ORAC expresses one of several measures of antioxidant capacity developed by scientists. The second describes how scientists view the recent trend by companies to advertise specific ORAC scores for their products and to compare their products to others in alleged antioxidant power.

Despite all the recent label claims, there's no standardized method for measuring antioxidant status and no definitions for antioxidant capacity, ability, activity, power, efficacy or other words companies might use to promote their products. The FDA has issued warnings against Lipton and other companies for making misleading and illegal claims about antioxidants.

ORAC and other tests measure antioxidant capacity of substances only in test tubes. How well antioxidants suppress oxidation and protect people against free radicals is anyone's guess.

The Canadian Food Inspection Agency notes on its website that "statements or claims about ORAC are not acceptable on foods because the relationship between ORAC scores and health effects in humans has not been established."

Similarly, the U.S. Department of Agriculture says that "ORAC values are routinely misused by food and dietary supplement manufacturing companies to promote their products."

Much more needs to be said on the recent rash of antioxidant claims. But it's nearly midnight on election eve. I want to vote early tomorrow, and then visit the Mt. Vernon home of George Washington with a family whose parents, recently sworn in as U.S. citizens, are excited about voting for the first time. I'm just excited about seeing this interminable election campaign finally come to an end.

So I'm going to stop now and continue with more on antioxidants and other supplement claims later.
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