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Supplements Take More Hits

Wednesday, November 10, 2010 // Uncategorized

Health does not come in a pill.

There is no evidence that taking dietary supplements is of benefit.  Some people think that it can’t hurt, but maybe it can.  Here  are some new alerts from Journal Watch.  

FYI:  There are different types of stroke.  The embolic type usually are blood clots which originate in the heart.  Thrombotic strokes are the most common type.  This is where a blood clot forms in an artery.  Hemorrhagic strokes are when a blood vessel ruptures and bleeds.

Association Found Between Vitamin E Supplements and Hemorrhagic Stroke
Vitamin E supplements have no effect on overall stroke incidence, but when stroke type is examined, the supplements significantly increase risk for hemorrhagic stroke, according to a BMJ meta-analysis.
Researchers examined data from nine trials encompassing some 120,000 subjects who’d been randomized to receive vitamin E or placebo and were followed for more than 1 year. Rates of stroke overall did not differ between groups. However, when the type of stroke was examined, ischemic strokes were significantly fewer among the vitamin recipients, while hemorrhagic strokes were significantly increased — by some 20%.
The authors say that the contrasting effects have tended to obscure vitamin E’s hemorrhagic risks. They write that the mechanism behind the effect is unknown and that it may stem from vitamin E’s interference with a vitamin-K-dependent clotting factor. They conclude that “indiscriminate widespread use of vitamin E should be cautioned against.”

If Vitamin E is prescribed by an ophthalmologist for macular degeneration that is a different story from someone who is taking Vitamin E for general health reasons.

{omega}-3 Fatty Acids and Prevention of Dementia

No evidence of benefit was noted in a 24-month trial.  

Among many proposed interventions to lower risk for or severity of dementia is supplementation with {omega}-3 fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are commonly found in oily fish. 

U.K. investigators enrolled 867 patients (age range, 70–79) from general practices; none had diabetes, and all had normal cognition (Mini-Mental State Examination scores ≥24). Participants were randomized to daily supplementation with EPA (200 mg) plus DHA (500 mg) or to olive oil placebo. The EPA and DHA dosages were based on U.K. dietary recommendations for fish consumption. The withdrawal and death rates were similar in the two groups — roughly 14% total. 

At 24 months’ follow-up, no differences were found between the two groups in a validated assessment of cognitive function based on verbal memory or in secondary outcomes related to global cognitive function, memory, or executive function. Adverse events were minor and similar in both groups, with a small incremental risk for flatulence, loose stools, and belching in the treated group. 

Comment: This randomized controlled trial is reportedly the longest and largest to evaluate {omega}-3 fatty acid supplementation for prevention of dementia. The negative results are consistent with the conclusions of a recent Institute of Medicine report that showed no clear support for any interventions that are purported to prevent dementia. 

Thomas L. Schwenk, MD 

Published in Journal Watch General Medicine May 11, 2010 

Citation(s):

Dangour AD et al. Effect of 2-y n–3 long-chain polyunsaturated fatty acid supplementation on cognitive function in older people: A randomized, double-blind, controlled trial. Am J Clin Nutr 2010 Apr 21; [e-pub ahead of print]. (http://dx.doi.org/10.3945/ajcn.2009.29121) Now this last article doesn’t deal with taking supplements, but with the most trndy of vitamins, Vitamin D.  Is taking Vitamin D good?  Does checking Vitamin D levels influence survival?  Bottom line:  We don’t know.

Does Vitamin D Status Affect Mortality?

No association between vitamin D status and mortality at 7 years was found.  

These days, many clinicians are checking vitamin D levels routinely. Patients with the lowest levels clearly are at risk for metabolic bone disease, which can be prevented with vitamin D supplementation. Another premise is that screening and supplementation will prevent a variety of disorders involving other organ systems. However, randomized trials in which researchers are examining the effect of vitamin D supplementation on mortality have not yet been completed, and not every observational study has demonstrated an association between vitamin D status and mortality. 

In this U.S. study, 1500 relatively healthy community-dwelling men (age, ≥65) were randomly selected from participants in the prospective Osteoporotic Fractures in Men study (Contemp Clin Trials 2005; 26:569). At baseline, 25-hydroxyvitamin D levels were <20 ng/mL in 25% of men, and between 20 and 30 ng/mL in 50% of men. During an average follow-up of 7 years, 22% of participants died. In both unadjusted analyses and in analyses adjusted for potentially confounding variables, no significant associations were observed between vitamin D levels (across quartiles) and all-cause, cancer-related, or cardiovascular mortality. 

Comment: This study reminds us that our understanding of the relation between vitamin D status and various sources of morbidity or mortality is far from complete. Whether screening and supplementation will save lives, prevent cancer, or prevent cardiovascular disease is unknown. 

Allan S. Brett, MD 

Published in Journal Watch General Medicine October 26, 2010 

Citation(s):

Cawthon PM et al. Serum 25-hydroxyvitamin D, parathyroid hormone, and mortality in older men. J Clin Endocrinol Metab 2010 Oct; 95:4625. (http://dx.doi.org/10.1210/jc.2010-0638

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