A common sobriquet for garlic is ‘the stinking rose,’ and if you’ve ever been up close and personal with garlic, you’ll readily understand the stinking part. But garlic also has rosier properties. Nearly all of the considerable health benefits afforded by garlic stem from its potent, pungent sulfur compounds. The advantages of either eating raw garlic or taking it in supplement form would require an entire article to explain, but briefly, studies show that garlic may lower blood cholesterol levels, lower elevated blood pressure and offer a hedge against the onset of several types of cancer. From a bodybuilding standpoint, several studies done with rats reveal some interesting effects of garlic. Those studies must be considered preliminary, however, for they involve animals rather than humans. Animal physiology may not always mimic human physiology, and so any animal studies must be confirmed by follow-up human studies. On the other hand, many effects of garlic shown in rat and other animal studies have been confirmed by subsequent human-based studies.
One study showed that rats on a high-fat diet that were given supplemental garlic had enhanced fat breakdown coupled with an increased amount of brown adipose tissue (BAT), a type of specialized fat that is known to convert fat calories into heat, thereby dissipating excess calories.1 A current theory on obesity has it that humans who appear to eat whatever they want with impunity’that is, without adding bodyfat’are able to do so because they have relatively abundant BAT activity in their bodies. Other studies show that garlic ingestion in rats increases the level of uncoupling protein and norepinephrine in the animals, explaining the elevated BAT thermogenic activity.
Because garlic appears to positively affect the secretion of hormones that promote fat loss, such as norepinephrine, scientists tested the effects of garlic ingestion in rats to see whether it affected the secretion of hormones that may affect body composition.2 The rats were fed diets that contained 40, 25 or 10 percent casein, a milk protein. Another group took in the same amounts of protein but were provided with supplemental garlic as well. After 28 days on the diets the rats that were getting the highest two levels of protein (40 and 25 percent) supplemented with garlic showed higher levels of testicular testosterone content, coupled with lower levels of corticosterone, than the rats that took in the highest-protein diets without garlic supplements. While neither body mass nor muscle was affected by garlic intake, the rodents that got the garlic showed a far greater
nitrogen-retention effect, which favors anabolic processes in muscle. The study further found that garlic appears to enhance such effects only when coupled with a higher protein intake. The 10 percent protein diet showed no significant anabolic effect, with or without supplemental garlic.
A second part of the study tested the effect of one of the primary sulfur compounds’the active ingredients in garlic’on the secretion of luteinizing hormone (LH), a pituitary gland hormone that controls testosterone synthesis in the body. The researchers found that the higher the dose of garlic sulfur compound, the greater the secretion of LH and, subsequently, testosterone, in the animals. The authors suggest that the promotion of norepinephrine release by garlic leads to a biochemical chain reaction resulting in greater LH and testosterone release.
Based on this study, should you stock up on garlic supplements or down raw garlic cloves with abandon? As noted above, this study is preliminary, involving a small group of rats. The results may or may not apply to humans. But garlic does offer many health benefits with few side effects. It makes sense to consider adding a quality garlic supplement, preferably one with an enteric coating to protect delicate active substances during digestion. Or you can simply add some whole raw garlic cloves to your diet, which has the dual effect of improving health while losing friends.
1 Oi, Y., et al. (1995). Garlic supplementation enhances norepinephrine secretion, growth of brown adipose tissue and triglyceride catabolism in rats. J Nutr Biochem. 6:250-255.
2 Oi, Y., et al. (2001). Garlic supplementation increases testicular testosterone and decreases plasma corticosterone in rats fed a high-protein diet. J Nutr. 131:2150-2156.