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Vitamins and Supplements: No Benefit, Possible Harms

Monday, February 24, 2014 // Uncategorized

Here is a patient summary on a study published in The Annals of Internal Medicine of vitamins except perhaps in certain groups of patients.  Following it is a summary of a study done on taking vitamin E and selenium to prevent prostate cancer.  The latter showed no benefit and possible harms based on baseline selenium levels.

 

Summaries for Patients | 25 February 2014

Vitamin, Mineral, and Multivitamin Supplements to Prevent Cardiovascular Disease and Cancer: Recommendations From the U.S. Preventive Services Task Force FREE ONLINE FIRST

Ann Intern Med. Published online 25 February 2014 doi:10.7326/P14-9012
 Who developed these recommendations?

The U.S. Preventive Services Task Force (USPSTF) developed these recommendations. The USPSTF is a group of health experts that reviews published research and makes recommendations about preventive health care.

What is the problem and what is known about it so far?

Cardiovascular disease (CVD) and cancer are common problems for Americans. Shortages of antioxidant vitamins (vitamins A, C, and E; β-carotene; and folic acid) are associated with the blood vessel changes that occur in CVD. Therefore, people have thought that taking these vitamins might decrease the chances of CVD. Information also suggests that these vitamins might decrease a person’s chances of cancer.

Many studies have examined associations between particular vitamins and CVD and cancer. The studies vary in quality, and their results often conflict. In 2003, the USPSTF recommended that people should not take β-carotene supplements to decrease their chances of CVD or cancer. At that time, the USPSTF concluded that there was not enough known to be able to make a recommendation for or against taking vitamins A, C, or E; multivitamins with folic acid; or combinations of these vitamins for the primary purpose of preventing CVD or cancer. The USPSTF wanted to update these recommendations on the basis of information that has become available since 2003.

How did the USPSTF develop these recommendations?

The USPSTF reviewed published studies to evaluate whether taking vitamin or mineral supplements prevents CVD and cancer in the general adult population.

What did the authors find?

The USPSTF found inadequate evidence to assess the balance of benefits and harms of supplements of single or paired vitamins, multivitamins, or minerals to prevent CVD or cancer. Only 2 vitamin supplements, β-carotene and vitamin E, have sufficient evidence to weigh the balance of benefits and harms. β-Carotene supplements have been associated with an increased risk for cancer in smokers, so the harms outweigh the benefits. Large, high-quality studies show that vitamin E supplements have no effect on CVD, cancer, or death rates. The USPSTF concludes that there is no benefit of vitamin E supplements to prevent these conditions.

What does the USPSTF recommend that patients and doctors do?

The USPSTF recommends that people do not take β-carotene or vitamin E supplements to decrease their chances of CVD or cancer. The USPSTF concludes that there is not enough evidence to assess the balance of benefits and harms of taking other single or paired vitamin or mineral supplements or multivitamins to prevent CVD and cancer.

What are the cautions related to these recommendations?

These recommendations focus only on healthy adults without special nutritional needs. These recommendations do not apply to children, women who are or may become pregnant, or people who are chronically ill or have a known nutritional deficiency.

Baseline Selenium Status and Effects of Selenium and Vitamin E Supplementation on Prostate Cancer Risk

  1. Alan R. Kristal,
  2. Amy K. Darke,
  3. J. Steven Morris,
  4. Catherine M. Tangen,
  5. Phyllis J. Goodman,
  6. Ian M. Thompson,
  7. Frank L. Meyskens Jr,
  8. Gary E. Goodman,
  9. Lori M. Minasian,
  10. Howard L. Parnes,
  11. Scott M. Lippman and
  12. Eric A. Klein

+ Author Affiliations


  1. Affiliations of authors: Cancer Prevention Program (ARK) and SWOG Statistical Center (AKD, CMT, PJG), Fred Hutchinson Cancer Research Center, Seattle, WA; Department of Epidemiology (ARK, GEG) and Department of Environmental Health (GEG), University of Washington, Seattle, WA; University of Missouri, Research Reactor Center, Columbia, MO (JSM); Harry S. Truman Memorial Veterans Hospital, Columbia, MO (JSM); Department of Urology, University of Texas Health Science Center at San Antonio, San Antonio, TX (IMT); Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA (FLM); Division of Cancer Prevention, National Cancer Institute, National Institutes of Health, Bethesda, MD (LMM, HLP); Moores Cancer Center, University of California San Diego, San Diego, CA (SML); Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH (EAK).
  1. Correspondence to:
    Alan R Kristal, DrPH, Cancer Prevention Program, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, M4-B402, Seattle, WA 98122 (e-mail: [email protected]).
  • Received July 26, 2013.
  • Revision received November 18, 2013.
  • Accepted November 23, 2013.

Abstract

Background The Selenium and Vitamin E Cancer Prevention Trial found no effect of selenium supplementation on prostate cancer (PCa) risk but a 17% increased risk from vitamin E supplementation. This case–cohort study investigates effects of selenium and vitamin E supplementation conditional upon baseline selenium status.

Methods There were 1739 total and 489 high-grade (Gleason 7–10) PCa cases and 3117 men in the randomly selected cohort. Proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for effects of supplementation within quintiles of baseline toenail selenium. Cox proportional hazards models were used to estimate hazard ratios, and all statistical tests are two-sided.

Results Toenail selenium, in the absence of supplementation, was not associated with PCa risk. Selenium supplementation (combined selenium only and selenium + vitamin E arms) had no effect among men with low selenium status (<60th percentile of toenail selenium) but increased the risk of high-grade PCa among men with higher selenium status by 91% (P = .007). Vitamin E supplementation (alone) had no effect among men with high selenium status (≥40th percentile of toenail selenium) but increased the risks of total, low-grade, and high-grade PCa among men with lower selenium status (63%, P = .02; 46%, P = .09; 111%, P = .008, respectively).

Conclusions Selenium supplementation did not benefit men with low selenium status but increased the risk of high-grade PCa among men with high selenium status. Vitamin E increased the risk of PCa among men with low selenium status. Men should avoid selenium or vitamin E supplementation at doses that exceed recommended dietary intakes.

This Article

  1. JNCI J Natl Cancer Inst (2014) djt456 doi: 10.1093/jnci/djt456 First published online: February 22, 2014
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