Many Americans don't get the officially recommended amounts of essential nutrients.
Despite ample evidence of that, an editorial by medical doctors from some top institutions conclude that multivitamins don't help well-nourished adults (Guallar E et al. 2013).
The authors of the anti-vitamin editorial hail from Johns Hopkins University, the UK's
Warwick Medical School, the American College of Physicians, and the Annals of Internal Medicine (which published the letter).
Their position was clear from the editorial's in-your-face title: “Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements”.
But many Americans eat high-calorie, nutrient-poor diets, and clearly need the nutritional “insurance” provided by multivitamin-mineral supplements.
Ironically, the folks eating the healthiest diets tend to take multivitamin-mineral supplements, while those who need them more go without.
We should stress that the anti-vitamin editorial concerned only studies of vitamin and mineral supplements … not omega-3 fatty acids or the beneficial fibers, sterols, and “antioxidants” in whole plant foods.
Before we review the studies that prompted the headline-grabbing editorial, it's important to answer two key questions.
How many Americans suffer a nutrient deficiency, and which among us are at highest risk of which deficiencies?
U.S. vitamin deficiencies vary by group
Government research shows that many Americans don't get the recommended daily allowance (RDA) for every essential nutrient.
The 2003-2006 U.S. Nutrition Examination Survey (NHANES) surveys found that 10 percent or less of the general population had nutrition deficiencies ... but that's up to 30 million people.
And nutrient deficiencies vary by age, gender, or race/ethnicity (CDC 2102):
- Children and adolescents were rarely deficient in vitamin B12 (< 1 percent), while older adults were more likely to be deficient (4 percent).
- Men were more likely to be vitamin C deficient (7 percent) compared to women (5 percent).
- Non-Hispanic black (31 percent) and Mexican-American (12 percent) people were more likely to be vitamin D deficient compared to non-Hispanic white people (3 percent).
- Vitamin B6, iron, and vitamin D were the nutrients most often lacking from American diets.
- Vitamin A, vitamin E, and folate had the lowest deficiency rates (less than 1 percent).
While nutrient deficiencies are limited to certain vitamins and minerals, and afflict some groups more than others, we're still talking about tens of millions of people at risk.
Critical editorial is based on clinical trials in well-nourished subjects
The authors of the anti-vitamin editorial relied heavily on the results of two recent studies that examined the disease-preventive effects of multivitamins and specific vitamins or minerals.
Study #1: USPSTF Evidence Review
The first was a clinical evidence review published by the United States Preventive Services Task Force, which found these effects of taking daily multivitamin-mineral supplements (Fortmann SP et al. 2013):
- High-dose beta-carotene raised lung cancer risk in male smokers.
- Men taking multivitamins enjoyed a seven percent drop in cancer risk.
- No clear benefit from vitamins A, C, or D, folic acid, selenium, or calcium.
- Neither vitamin E nor beta-carotene prevented cardiovascular disease (CVD) or cancer.
As they wrote, “Limited evidence supports any benefit from vitamin and mineral supplementation for the prevention of cancer or CVD.
Two trials found a small, borderline-significant benefit from multivitamin supplements on cancer in men only and no effect on CVD.” (Fortmann SP et al. 2013)
However, the authors noted that while they analyzed the best available clinical studies, most of these involved older people free of known nutritional deficiencies who took vitamins or minerals at modest doses for less than 10 years.
Study #2: Physicians' Health Study II Vitamin Trial
The second study cited by the authors of the anti-vitamin editorial was a clinical trial within the larger Physicians' Health Study II (PHS II).
For the trial 5,947 male physicians aged 65 years or older took either multivitamin-mineral or placebo pills daily for 12 years, to see if they gained any brain/thinking benefits (Grodstein F et al. 2013).
The results did not show any gains for the vitamin group: “In male physicians aged 65 years or older, long-term use of a daily multivitamin did not provide cognitive benefits.”
But as the authors noted, “[The] doses of vitamins [given] may be too low or the population may be too well-nourished to benefit from a multivitamin.”
(Compared with the general public, doctors are much more likely to be well-nourished and free from nutrient deficiencies.)
And the authors ignored the fact that the overall Physicians' Health Study II – which involved more than 15,000 doctors – found that vitamin-mineral supplements reduced the risk of cancer and cataracts substantially.
Oddly, the authors of the anti-multivitamin editorial appear to assume that all Americans eat healthy diets and get all the essential nutrients they need from food alone.
In truth, medical research has just begun to explore the potential benefits of nutritional supplements for the majority of Americans who do not eat a healthy diet and likely suffer from the highest rates of nutrient deficiencies.
Vitamin supplements may not reliably prevent heart disease, cancer, or other major disorders.
But multivitamin supplements can and do provide “insurance” against nutritional deficiencies that can lead to major diseases or lesser – but still debilitating – evils.
Review finds vitamin D doses above the RDA don't prevent major diseases
Vitamin D is proven essential to bone health and basic immune functions, and many Americans have low blood levels.
A large body of epidemiological evidence linking blood levels of vitamin D well above the average to reduced risk of heart disease and certain cancers.
Most of the preventive-health hopes pinned on higher-than-average vitamin D intakes and blood levels stems from epidemiological studies.
However, epidemiological studies cannot prove that a nutrient prevents a disease … they can only detect associations between a given nutrient and risk of a given disease.
And the authors of the new review find little evidence from clinical trials suggesting that higher-dose vitamin D supplements prevent disease.
Recently, French researchers analyzed data from epidemiological and clinical studies on vitamin D and disease.
They looked at 290 epidemiological studies, which suggest – but cannot prove – that high blood levels of vitamin D help prevent major diseases (Autier P et al. 2014).
The epidemiological evidence linked higher vitamin D levels with reduced risks for adverse cardiovascular events (maximum 58 percent drop), diabetes (maximum 38 percent drop), colorectal cancer (maximum 33 percent drop), and ‘all-cause mortality' (maximum 29 percent).
Higher vitamin D levels were also linked to healthier cholesterol levels, inflammation levels, glucose (blood sugar) metabolism, infectious disease rates, weight, and brain function.
However, when the French team analyzed data from 172 randomized clinical trials – on conditions other than poor bone health – the results indicated no reduction in risk of non-bone diseases.
This led the researchers to conclude that that low vitamin D may be a result of, rather than a cause of, ill health.
The authors of the review proposed that drops in vitamin D levels signal deteriorating health, and that inflammatory and other aging processes associated with major diseases drain vitamin D levels … which would explain why vitamin D deficiency occurs in many disorders.
If true, this makes it critical for those suffering from chronic ill health to keep their vitamin D levels at healthily high levels.
- Autier P et al. Vitamin D status and ill health: a systematic review. The Lancet Diabetes & Endocrinology - 1 January 2014 ( Vol. 2, Issue 1, Pages 76-89 )
- Centers for Disease Control and Prevention (CDC), Second National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 2012: Executive Summary. Accessed at http://www.cdc.gov/nutritionreport/pdf/ExeSummary_Web_032612.pdf
- Fortmann SP, Burda BU, Senger CA, Lin JS, Beil TL, O'Connor E, Whitlock EP. Vitamin, Mineral, and Multivitamin Supplements for the Primary Prevention of Cardiovascular Disease and Cancer: A Systematic Evidence Review for the U.S. Preventive Services Task Force [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2013 Nov.
- Fortmann SP, Burda BU, Senger CA, Lin JS, Whitlock EP. Vitamin and Mineral Supplements in the Primary Prevention of Cardiovascular Disease and Cancer: An Updated Systematic Evidence Review for the U.S. Preventive Services Task Force. Ann Intern Med. 2013 Nov 12. doi: 10.7326/0003-4819-159-12-201312170-00729. [Epub ahead of print]
- Grodstein F et al. Long-Term Multivitamin Supplementation and Cognitive Function in Men: A Randomized Trial. Ann Intern Med. 2013;159(12):806-814-814. doi:10.7326/0003-4819-159-12-201312170-00006
- Guallar E et al. Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements. Annals of Internal Medicine. 2013 Dec;159(12):850-851.