Research suggests that long term consumption of garlic may reduce the risk of developing certain diseases such as heart disease and cancer. These health benefits are attributed to the sulphurous compounds that are contained within garlic, although the chemistry is complex and not fully understood. Interestingly, garlic also contains another group of unrelated steroidal chemicals, the saponins, that may have important regulatory effects on mammalian endocrine function. Because of the similarity in structure between saponins and mammalian steroid hormones, researchers1 have investigated the possibility that garlic raises testosterone in rats. Rats were fed a high protein diet with and without garlic powder while various physiological parameters were monitored. Rats fed the high protein diet in combination with garlic powder had higher levels of testosterone when compared to control animals which were fed just the high protein diet.
The researchers also reported that the rats fed garlic had lower levels of plasma corticosterone, irrespective of a high or low protein diet. A breakdown product of testosterone called 17-ketosteroid was also elevated in rats fed the high protein diet and garlic combination suggesting higher levels of male sex hormones in these rats. The rats fed the high protein and garlic combination also had improved nitrogen retention. The high protein diets were around 40 % protein, and garlic supplementation was 8 grams of garlic powder per kg of food. In a follow up experiment, the rats were fed a sulphur containing compound from garlic called diallyldisulfide, and found that plasma luteinising hormone concentration increased in a dose dependent manner. This suggests that the sulphurous components of garlic may be responsible for at least part of the hormonal effects seen in rats. It is possible therefore that garlic raises testosterone in humans.
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