Filed under: Dietary supplements
The dietary supplement and fitness industries are filled with sport drinks, powders, bars, pills, gels, footwear, clothing, and an array of devices all claiming to provide you with a competitive advantage, whether it be improved performance or enhanced recovery. With the ever-growing popularity of team and individual sports, professional and recreational athletes of all ages are an easy target for these claims. But how many of these claims are backed by evidence-based research?
A recent report now reviews the quality of evidence behind the claims of improved sports performance made by advertisers for a wide range of sports-related products, including sport drinks, supplements, footwear, and clothing. The team identified 431 performance-enhancing claims for 104 products advertised in more than 100 general, sport, and fitness magazines in the UK and U.S. for a single month in 2012. They found that more than half of the advertisements and their associated websites provided no evidence to support the claims of enhanced sports performance. Only 146 references were found, and only 74 of these met basic criteria for research quality and almost all of the 74 were found likely to be biased or lacking scientific objectivity. Only three studies were rated as “high” quality and probably unbiased. Such lack of evidence makes it very difficult for consumers to make well-informed decisions about using performance-enhancing sports products.
This review makes it clear that many of the claims made for sports and fitness products lack reliable evidence to support them and that more and better studies are needed to help inform consumers. In the meantime, consumers should be cautious when reading claims of enhanced performance and recovery and always remember that “true” evidence-based results mean that a substantial number of independent research studies have been performed, with findings that clearly support the claims made by advertisers. Presently, there is still no substitute for sound physical conditioning and nutrition practices.
For more information on dietary supplements and how to choose supplements safely, please visit Operation Supplement Safety (OPSS). For information on physical fitness and conditioning, please explore HPRC’s Physical Fitness domain. The original British Medical Journal open-access article is available online.
Tribulus terrestris is used as an ingredient in some dietary supplement products marketed as testosterone “boosters” and/or to enhance muscle strength. What is it and does it work? Read this OPSS FAQ about Tribulus terrestris to find out. Also, be sure to check the OPSS section often, as we add answers to other questions about ingredients in performance-enhancing and bodybuilding supplements. OPSS can help you learn how to choose supplements safely.
If you have a question about a particular dietary supplement ingredient or product, and you can’t find the answer on our website, please use our “Ask the Expert” button located on the OPSS home page.
Cheeba Chews are marketed as chocolate taffy, but they actually contain an illegal substance. Read the Operation Supplement Safety (OPSS) FAQ to find out more about these products and whether they are legal for members of the military community to consume. Be sure to check back often as we add answers to other questions and topics in the OPSS section of HPRC’s website.
Since we first posted our list of DMAA-containing dietary supplement products in December 2011, and especially since FDA’s announcement in April 2013, the number of products being manufactured with this ingredient has continued to decline. Our search does still occasionally turn up products with DMAA that were not on our previous lists: just six new products have been added since our last update in April 2013. Despite these additions, this update shows that about 80 dietary supplement products are apparently still being manufactured with DMAA, but note that many are by non-U.S. sources. Over the lifetime of this list 125 products have been discontinued or reformulated to exclude DMAA, including some of the most well-known ones. To the best of our knowledge and searching, 68 of these no longer appear for sale, even from distributor stock. You'll find our updated list of products containing DMAA here.
Dendrobium is being used as a dietary supplement ingredient in some pre-workout products marketed to enhance physical or athletic performance. What is it? And is it effective? Read this OPSS FAQ about dendrobium to find out. Be sure to check back often, as we add answers to other questions about ingredients in performance and weight-loss supplements and how to choose supplements safely.
If you have more questions about a particular dietary supplement ingredient or product, please use our “Ask the Expert” button located on the OPSS home page.
Synthetic drugs are laboratory-made substances marketed and sold as alternatives to illegal drugs such as marijuana, cocaine, and amphetamines. Although most are advertised as “all-natural,” they may have serious health effects and violate the Uniform Code of Military Justice (UCMJ). HPRC takes a look at two examples of synthetic drugs, their legal status, and how they can affect service members in “HPRC’s Answer: Synthetic Drugs of Abuse.”
Carnitine is a naturally occurring substance in the human body that helps cells use fat for energy. The liver and kidneys can produce carnitine from amino acids provided by the diet, but carnitine also comes from many foods, especially red meat, and is an ingredient in many dietary supplements and energy drinks.
Sometimes doctors use carnitine to treat certain heart conditions. Recent clinical trials suggest that carnitine supplements may help reduce many of the complications associated with heart attacks, such as chest pain and irregular heart rhythms.
But new research suggests that long-term consumption of dietary carnitine also may play a role in the development of atherosclerosis—“hardening of the arteries”—especially in people who eat red meat regularly. So what’s the bottom line? More research is needed to determine the risks and benefits associated with carnitine.
You can learn more about carnitine in HPRC’s Dietary Supplement Classification System.
The Food and Drug Administration (FDA) has issued a Consumer Update warning of the potential dangers of DMAA, which was announced illegal in dietary supplements on 11 April 2013. DMAA is also referred to as dimethylamylamine and other names. This dietary supplement product ingredient has been used in many weight-loss, bodybuilding, and performance-enhancement products. FDA received numerous reports of illnesses and death from the use of products containing DMAA; commonly reported reactions include heart and nervous system problems as well as psychiatric disorders. DMAA has been the focus of conflicting information regarding whether or not it is a natural extract from geranium. FDA has now found “the information insufficient to defend the use of DMAA as an ingredient in dietary supplements.” Online, FDA also stated, "Dietary supplements containing DMAA are illegal and FDA is doing everything within its authority to remove these products from the market."
For more information, read the FDA Q&A on DMAA here.
Raspberry ketone, touted to be an effective fat-loss and weight-loss supplement, occurs naturally in various red raspberries. The raspberry ketone in supplements is probably produced in the laboratory, as it would be too expensive to extract it from real raspberries. FDA recognizes that raspberry ketone as a food additive is “Generally Recognized as Safe” (GRAS) to consume in small amounts. However, the long-term effects in humans who consume it as a supplement are unknown. For more information, read HPRC’s InfoReveal on “Raspberry ketone.”
Be extra cautious when taking dietary supplements before and after surgical procedures; some products can have serious negative effects on surgical procedures. For instance, certain supplements prevent certain blood cells (platelets) from clumping, resulting in excessive bleeding during surgery. Some of the ingredients commonly found in supplements that hinder platelet aggregation are ginko biloba, saw palmetto, glucosamine, black tea, fish oil, and garlic. If you are having a surgical operation, consider abstaining from these items or consume these items in moderation a few weeks before and after the procedure. For more a complete list of products and additional information, including other surgical risks associated with dietary supplements, read this web page from the Natural Medicines Comprehensive Database. And always read product labels carefully; many include warnings of potential medical risks, including the length of time prior to surgery that you should discontinue use.