Marketed Supplements with No Performance Benefits

A number of widely-used supplements have been marketed so well to athletes via the popular press for so long that they appear entrenched in the sporting culture. However, little scientific support exists for their use by athletes. These include:

Ginseng Extracts

Ginseng extracts have been suggested to reduce fatigue, improve endurance, strength, mental functioning and recovery. To date, there is a lack of scientific data to support any of these claims.


Carnitine is naturally-produced in the liver and kidney from amino acids found in the diet and is found naturally in most animal foods, some of which is lost during cooking. Carnitine supplementation has been suggested to lower body fat levels, explaining why body-builders suggest its use at 1-6 grams/day is great for ‘getting ripped’ or ‘cutting up’. However, research has also shown that the body produces enough of its own carnitine, can get enough in the diet, and that supplementing with carnitine does not lead to increased muscle carnitine levels.

Coenzyme Q10

Coenzyme Q10 or ubiquinone is commonly found in animal foods and in low amounts in plant foods. It has been marketed to “promote vigour”, “enhance aerobic capacity”, and reduce the oxidative damage of exercise.  However, recent research has suggested that instead of acting as an antioxidant, it actually increases oxidative damage in athletes undertaking high intensity training.

Chromium Picolinate

Chromium picolinate is an essential element required by the body to enhance the action of insulin in taking up glucose from the blood. It is found naturally in yeast, nut and legumes (beans, seeds), some fruit and vegetables, chocolate, wine and beer. The marketers suggest that chromium will enhance the metabolism of glucose, fat and protein and thus increase muscle mass and strength while lowering body fat – all very attractive to an athlete of any age. However, well-controlled studies have shown no benefit in any of these areas other than what training alone can provide. However, if an athlete is not getting the dietary intake of chromium via the foods mentioned above, then low levels of supplementation might be needed as high levels have been shown to be linked to iron deficiency.

Medium Chain Triglycerides (MCT’s)

MCT’s are fatty acids found in butter, palm, coconut and kernel oil. They can also be found on the web or in come health food shops as MCT Fuel, MCT Oil, MCT Gold, Prozone Drink, MCT Powder, or UltraGel. Because they are smaller than most fats found in the normal diet, they empty from the stomach more easily, are more easily absorbed by the small intestine, and enter the energy making part of muscle cells (mitochondria) more easily than the long-chain triglycerides. In endurance exercise, if they are consumed during exercise, they theoretically might spare carbohydrate and thus improve endurance in long events. One often quoted 1996 study showed a 2.5% improvement in 40-km cycling time trial performance following MCT ingestion. However, no study since then has shown improved performance. Indeed, taken collectively, the later studies showed that MCT use does not improve performance, does not spare muscle carbohydrate and in large doses causes gut upsets such as nausea and diarrhoea. Further support for not using MCT’s is the fact they lead to elevated blood cholesterol and trigyceride levels, thus increasing the risk of heart disease in aging athletes.


Prohormones (DHEA, Androstenedione) are so named because they are precursors in the steroid pathway leading to the anabolic (muscle building) hormone, testosterone. Some commercially available products such as Tribulus and Saw Palmetto are marketed as having similar anabolic activity as the prohormones. Despite being banned by the IOC, prohormones are marketed to athletes as a way to promote fat loss, gain muscle mass and strength, increase sex drive, reverse the effects of aging, and improve the immune system. However, in one of the few studies that has examined these claims following training, a study examined the effect of 300 mg/day of androstenedione during 8 weeks of weight training in healthy young but untrained males, half of whom took the hormone and half who didn’t. Testosterone levels did not change, the good cholesterol (HDL) decreased, and the female hormone levels increased in the group that took androstenedione!  As expected with weight training, muscle mass and strength increased and fat levels decreased in both groups, all of whom had normal levels of testosterone before and after the study. However, the group that took the prohormone and the group that took none both changed the same amount, suggesting that the positive changes were due to the weight training and not the prohormone. However, the researchers suggested that androstenedione might be useful in older males and females or endurance athletes, all of whom are characterized by lower than normal testosterone levels.

DHEA decreases with aging and been investigated as a performance-enhancing agent. A similar study to the one above found that DHEA (like androstenedione taken at 100 mg/day) did not lead to any increases in testosterone or significant increase in muscle mass or strength compared to that effect expected after 8 weeks of weight training. A similar study of the effect of Tribulus by the same group, also showed no effect on performance.

In summary, the studies examining the effects of prohormones on muscle mass and strength to date have found no benefit on testosterone levels, no increases in strength and muscle mass, and some negative side-effects that place an older person more at risk of heart disease.  A little bit of trivia (!?) regarding anabolic steroid use in athletes. We have for many years known about the negative side effects of anabolic steroid use. These include increased risk of heart disease, sudden death, increased cholesterol levels, and heart size abnormalities. However, some long-term studies have recently been completed on the death rates of anabolic steroid users who were monitored over a 12-year period from the early 1980’s. The rate of death amongst the users was 12.9% compared to 3.1% in a normal age-group, a rate 4.6 times higher than normal.