The humble multivitamin is one of the most basic health maintenance aids, taken by millions of people daily. It is surprising, then, how little is really known about what should and should not be in a daily "multi." There are literally hundreds of brands, but few guides to help you choose which are best. A look at some recent efforts to make sense of multivitamin mayhem.
It is ironic that at a time when science and technology have made it possible to send remote-controlled robot explorers to Mars, there are still so few definitive answers about basic Earthly matters like how to optimize nutritional status to prevent or ameliorate chronic diseases.
Consider that most humble of preventive health tools: the multivitamin. It is surprising how little is really known about what ought to be in a multivitamin to provide optimal preventive health benefit.
Current estimates suggest roughly 40% of all US adults regularly take some form of multivitamin. These numbers have grown steadily over the last two decades. According to a study from the National Cancer Institute’s Division of Cancer and Population Sciences, the percentage of adults using vitamin and mineral supplements daily increased from 23.2% in 1987, to 33.9% in 2000. This pattern was consistent for both men and women, and across all racial and ethnic groups (Millen AE, et al. J Am Diet Assoc. 2004 Jun; 104(6): 942–950).
Beyond the common-sense notion that taking a multivitamin is a good idea, what motivates people to take multivitamins? What is guiding product choices? Of what would an ideal multivitamin consist? Who should and should not take a daily multi, and what benefits can an individual reasonably expect from it? Science is far from adequate to definitively answer these questions.
Even a casual foray into the realm of preventive nutrition quickly leads to a confusing cacophony of strong epidemiologic correlations, variable clinical outcomes, bold marketing claims, and equally forceful calls for caution.
For example, over the last 12 months, we’ve learned that multivitamins slow progression of HIV infection and prolong the lives of HIV infected people, at least in East Africa (Fawzi W, et al. N Engl J Med. 2004 Jul 1; 351(1): 23–32). We’ve also learned that some antioxidant vitamins can reduce risk of Alzheimer’s disease, at least in Cache County, Utah (Zandi PP, et al. Arch Neurol. 2004 Jan; 61(1): 82–88). There’s also evidence that multivitamins may reduce cataracts and lens opacities (Mares JA. Nutr Rev. 2004 Jan; 62(1): 28–32), and that they can produce major declines in c-reactive protein (CRP) levels, a key marker of cardiovascular risk (Church TS, et al. Am J Med. 2003 Dec 15; 115(9): 702–707).
But we also learned that while good nutrition habits are best acquired early in life, it might not be a good idea to give multivitamins to very young children. A recent study showed that giving multivitamins to kids under the age of 3 could increase the risk of asthma and food allergies (Milner JD, et al. Pediatrics. 2004 Jul; 114(1): 27–32). And despite the good news about CRP, a separate study showed multivitamins produce no meaningful reduction in LDL, blood pressure, or hemoglobin A1c in people with existing CVD (Stys T, et al. Clin Cardiol. 2004 Feb; 27(2): 87–90). Studies of the impact of multivitamins on clinical endpoints ranging from myocardial infarction to colorectal cancer come to very variable conclusions, as have trials assessing individual antioxidant vitamins.
Arguably, the most well rounded review on the subject of vitamins for disease prevention is from Drs. Robert Fletcher and Kathleen Fairfield, of Harvard’s Department of Ambulatory Care and Prevention. In a pair of landmark 2002 articles, Fletcher and Fairfield note that, “suboptimal intake of some vitamins, above levels causing classic deficiency, is a risk factor for chronic diseases and common in the general population, especially the elderly.” They stress that most US adults do not obtain optimal vitamin levels from diet alone (Fairfield KM, Fletcher RH. JAMA. 2002 Jun 19; 287(23): 3116–3126. Fletcher RH, Fairfield KM. JAMA. 2002 Jun 19; 287(23): 3127–3129).
Citing widespread sub-clinical deficiencies in folic acid, vitamins B6, B12, A, E, and D, and outlining the correlations between these deficiencies and a host of chronic diseases, they argue that in the absence of definitive negative evidence, “it appears prudent for all adults to take vitamin supplements.” However, they also point out the dangers of excessive supplementation, especially with fat-soluble compounds like vitamin A.
The Fletcher and Fairfield papers are notable for their fairness and neutral tone in a field fraught with heated polemics. They are also notable as the most pro-supplementation articles ever published in JAMA. Some in the field believe they reflect a slow but welcome attitude change in conventional medicine—a shift away from the old “expensive urine” dogma about vitamin supplements.
One would be hard pressed, though, to derive firm clinical recommendations or supplement product guidelines from these papers, or in fact, from any of the existing literature. Federal resources are not of much help either. Obvious reference sources, like the National Center for Complementary and Alternative Medicine (NCCAM), and the NIH’s Office of Dietary Supplements, have little relevant information to guide the choice and use of multivitamin products.
It seems that beyond the basics of preventing overt deficiencies like scurvy, pellagra, rickets and the like—the core principles of which were canonized as the Recommended Daily Allowances (RDAs)—there’s little scientific consensus on how to optimize nutrition to prevent degenerative conditions like heart disease, cancer, diabetes, arthritis, and dementia. But given the prevalence of these diseases and the dire state of health care financing, if ever there was a subject warranting an all-out, national, cross-disciplinary scientific initiative, it is this one.
Lyle MacWilliam, a former member of Canada’s Parliament, is a biochemist and public health advocate who has spent the better part of the last decade trying to develop rational science-based guidelines for optimal nutrition. He believes it is high time the scientific and political establishments join together to face this issue.
“In both Canada and the US, the health systems are being sorely challenged. It is bad now, and it is going to get orders of magnitude worse in 20 years. If we began the practice of prevention, and included in that, tax incentives and benefits to stay healthy, and also included judicious use of supplements as a preventive strategy, we might alleviate some of the impending crisis. So far, we’ve failed to take those initiatives,” he told Holistic Primary Care.
Mr. MacWilliam served on the Canadian Ministry of Health’s expert advisory panel that recently overhauled Canada’s regulatory framework for natural health products. He is also author of The Comparative Guide to Nutritional Supplements, a comprehensive and user-friendly basic nutrition science primer and product review guide (the book can be obtained at www.comparativeguide.com).
The Comparative Guide offers a clear explanation of the role of free radicals and oxidative stress in the deterioration of cellular machinery and emergence of various common diseases. It makes a strong, well-documented case for routine supplementation with antioxidant multivitamins, and underscores the inadequacy of the RDAs in providing adequate levels of vitamins to manage oxidative stress.
“When vitamins first entered the market years ago, formulations were based exclusively on the RDA system established in the 1940s. These were the minimal values needed to avoid acute deficiency. But it is increasingly recognized that the old RDAs are not adequate to achieve optimal health and prevent degenerative diseases,” said Mr. MacWilliam. He added that the National Academy of Sciences’ newer Daily Reference Intakes (DRIs), which upped the levels of some key antioxidants, still fall short of what he and others believe are optimal levels.
For example, the current DRI for selenium is 55 mcg per day, though a 1996 study showed that selenium could reduce total cancer mortality, including prostate, colon and lung cancer deaths, at a level of 200 mcg per day (Clark LC, et al. JAMA. 1996; 276(24): 1957–1963). The DRI for folic acid is only 400 mcg per day, though several recent studies indicate that levels of 500–1,000 mcg are needed to reduce homocysteine and cardiovascular risk.
There are literally thousands of multivitamin products now available, targeting every imaginable demographic. But there is surprisingly little consensus as to what a good multivitamin ought to contain. Mr. MacWilliam’s book is among a number of independent efforts to define rational criteria for multivitamins and to rank popular brands accordingly. Others efforts include the Center for Science in the Public Interest’s (CSPI) “Best Bites” series, and ConsumerLab’s product testing program. All of them, while stepping in the right direction, have their limits.
Mr. MacWilliam’s Comparative Guide ranks over 500 commercially available multivitamins against a “Blended Standard” profile of 39 vitamins, minerals and other nutrients. In the absence of definitive national consensus guidelines beyond the RDAs and DRIs, Mr. MacWilliam derived the Blended Standard by averaging recommendations made by 7 authors who have published their own criteria for optimal daily preventive nutrition.
The authors cited are: Phyllis Balch, CNC (Prescription for Nutritional Healing: The A-to-Z Guide to Supplements), Michael Colgan, PhD (The New Nutrition: Medicine for the New Millennium), Earl Mindell, PhD (Earl Mindell’s Vitamin Bible for the 21st Century), Michael Murray, ND (Encyclopedia of Nutritional Supplements), Richard Passwater, PhD (The New Supernutrition); Ray Strand, MD (What Your Doctor Doesn’t Know About Nutritional Medicine May Be Killing You), and Julian Whitaker, MD (Dr. Whitaker’s Guide to Natural Healing). These writers did not participate directly in creation of the Comparative Guide.
CSPI’s “Best Bites” guidelines take a similar overall approach. They look beyond the RDAs and DRIs, citing the most recent prevention trials to determine optimal levels of key vitamins and minerals. They then rank products according to the degree to which their stated nutrient levels compare with these standards (view the CSPI guidelines at: www.cspinet.org/nah/4_00/pickamulti.htm). In general, both CSPI’s criteria and the Comparative Guide‘s Blended Standard call for nutrient levels higher than the 2001 DRIs, but with few exceptions, neither exceeds the NAS’s established Upper Limits for safety.
When compared against the Blended Standard, the top 10 multivitamins in the Comparative Guide are: USANA Health Sciences’ Essentials; Douglas Laboratories’ Ultra Preventive; Vitamin Research Products’ Extend Plus; Source Naturals’ Life Force Multiple; Source Naturals’ Elan Vital; USANA’s Essentials (Canadian formulation); FreeLife’s Basic Mindell Plus; Life Extension Foundation’s Life Extension Mix; Karuna’s Maxxum 4; and Ultimate Nutrition’s Super Complete.
While there are many excellent products on the market, Mr. MacWilliam said he was “surprised by how many products scored poorly.” Low-scoring products included some very well known consumer brands such as Centrum, One-A-Day, Solgar and Schiff.
“There are a lot of products out there just emulating the old RDA’s. Our standard raises the bar fairly high because we were trying to set a standard for optimal nutrition. A lot of products, including some big brands, are fairly mediocre from that viewpoint.”
The Comparative Guide‘s approach to standard setting makes sense in principle. But critics have charged that a number of the experts whose recommendations went into the Blended Standard have relationships with USANA, the multi-level marketing company that had several high-scoring products, including the number one ranked multivitamin. Though Mr. MacWilliam himself has been on the scientific advisory board for USANA, he dismisses the notion that the book is intentionally or unintentionally biased to support USANA.
“The purpose was to try and develop criteria based on the most current science. Any bias in the criteria reflect the biases of the individual cited authors, and these are weighted in a lot of different directions,” Mr. MacWilliam said. While some authors have relationships with USANA, others have relationships with other nutritional companies including Natural Factors and Solgar.
The biggest limit of the Comparative Guide methodology, and one that applies equally to CSPI’s rankings, is the exclusive reliance on product labels. Mr. MacWilliam acknowledged that he and his colleagues did no analytical chemistry to determine if the levels of vitamins indicated on product labels are actually in the pills or capsules. “By reason of sheer cost, we could not test actual chemical constituents of all these products.”
ConsumerLab, an independent consumer information company focused on dietary supplement quality, does at least some analytical chemistry on at least some products. Founded by Todd Cooperman, MD, a physician, and William Obermeyer, PhD, formerly a natural products chemist with the FDA, ConsumerLab (CL) looks at supplements with an eye toward determining if what’s stated on the label is actually in the bottle.
For its recent multivitamin report, CL tested 24 off-the-shelf products to see whether their formulas contained the labeled levels of vitamin A (β-carotene and retinol), vitamin E (natural or synthetic), vitamin D, folate, ascorbic acid, B vitamins (niacin, pyridoxine, riboflavin), calcium, iron, zinc, magnesium and manganese. CL also tested for disintegration (a stand-in for absorbability) and lead contamination.
Only 14 of the 24 “passed,” meaning that the pills, capsules or liquids contained at least 100% but not more than 150% of the amount of each of these nutrients stated on the product labels (CL’s multivitamin report, as well as reports on other product categories are available at www.consumerlab.com).
There were some surprising failures, notably the popular Theragran-M formula, which contained over 3 mcg of lead per daily serving, and Futurebiotics Advanced Women’s Formula, which did not deliver the amount of vitamin A stated on the label. Both products are manufactured by Bristol-Myers Squibb.
Though CL does attempt to put some chemistry into its product assessment, the main problem with this system is that at best it can only validate label listings; it does not provide any guidance on whether the nutrient levels in a given product are adequate to provide meaningful disease prevention benefits. In other words, a product may very well contain what it says it does, but if this level is inadequate to produce any health benefit, its value is questionable.
CL has only tested a small fraction of the multivitamin products currently in the market. Interestingly, there were relatively few overlaps between products analyzed by CL and products ranked by the Comparative Guide.
Given the wide variety of multivitamin products, not to mention variance in the quality of their manufacture, it is not surprising that clinical trials with multivitamins have had such variable outcomes. Health care practitioners, nutrition scientists, and many supplement industry leaders agree that there is a dire need for new standards for optimal nutritional supplementation, and an equally pressing need for valid and unbiased methods of evaluating vitamin products.
All agree, however, that this is a long way off. Such an endeavor will require considerable amounts of money, not to mention high levels of cooperation across disciplines and industries. But the profound impact of chronic degenerative diseases and the preventive and therapeutic potential represented by optimal nutrition, will hopefully provide motivation for rapid movement in this direction.
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