It is common for athletes to take multivitamin and multimineral supplements, but there is no evidence that these supplements enhance performance in sports that require power. Despite the lack of scientific evidence to support taking supplemental doses of vitamins, there is a common belief among power athletes that a number of these vitamins enhance strength. The vitamins and minerals sold to enhance strength include vitamin B-12, vitamins C, E, and beta-carotene (antioxidants), chromium, boron, and magnesium.

Vitamin B-12

The theory behind vitamin B-12 is that it is essential for the synthesis of DNA, and having more DNA enhances muscular development. However, there is no evidence that vitamin B-12 or B-12 derivatives have any beneficial impact on muscular development or on improvements in strength.

Antioxidants

The antioxidant vitamins (C, E, and beta-carotene) may speed recovery time for sore muscles. If this is found to be true, there may be a real benefit to taking antioxidants (which are easily obtained by consuming fresh fruits and vegetables) at the initiation of a strength-training program. It is during this phase that muscles more easily become sore, so the benefit (if there is one) would be greatest at this time.

Chromium

Chromium is essential for the effective metabolism of glucose and is the key component in a compound called “glucose tolerance factor,” or GTF. Chromium enhances the effectiveness of insulin and is marketed as a substance that can enlarge muscles, improve strength, and lower body fat. Typically, chromium is marketed in the “chromium picolinate” form (chromium attached to a picolinate carrier). Recent evidence suggests that chromium picolinate is ineffective in doing any of the things it is supposed to do.

Boron

Boron is an important mineral that may help prevent the bone disease osteoporosis. In 1992, a study on boron-deprived postmenopausal women reported that boron supplements doubled their serum testosterone levels.33 However, this study showed that continued intake of boron did not further enhance serum testosterone, and supplementation of males had no impact on testosterone, at all. Another study on bodybuilders indicated that boron supplementation had no impact on serum testosterone, lean body mass, and strength.

Magnesium

Magnesium is the second most predominant (after potassium) intermuscular electrolyte, and it has a number of important functions related to protein synthesis and muscular contractions. It appears that magnesium supplementation is more useful in untrained individuals who are initiating a training program than in athletes who are already well trained. In one study, it was found that both untrained males and female who were in a seven-week weight training session had important increases in muscular power as a result of magnesium supplementation.

Fats and Fat Derivatives

Fat intake may be important (critical for some athletes) as a means of obtaining sufficient energy to maintain a high body mass. A number of fat derivatives are marketed, however, because of their supposed positive impact on energy metabolism, or because they are chemically similar to hormones that enhance muscular development. For instance, some plant sterols (called phytosterols) are similar to the hormone testosterone.36 However, there is limited evidence that any of these fat-derivative functions work to enhance muscle mass or athletic performance. The major fat-derivative products marketed to athletes include medium-chain triglycerides (MCT oil), omega-3 fatty acids (O-3FAs), gamma oryzanol, and smilax. See table 5.4 for a summary of their functions.