Environmental factors affecting testosterone levels include:
- Weight loss may result in an increase in testosterone levels. Fat cells synthesize the enzyme aromatase which converts testosterone, the male sex hormone, into estradiol, the female sex hormone.[106]
- The hormone vitamin D in levels of 400–1000 IU (10–25 mcg) raise testosterone level.[107]
- Zinc deficiency lowers testosterone levels[108] but over supplementation has no effect on serum testosterone.[109]
- Magnesium raises free testosterone according to studies.[citation needed]
- Implicit power motivation[clarification needed] predicts an increased testosterone release in men.[110]
- Aging reduces testosterone release.[111]
- Hypogonadism
- Sleep (REM dream) increases nocturnal testosterone levels.[112]
- Resistance training increases testosterone levels,[113] however, in older men, that increase can be avoided by protein ingestion.[114]
- Licorice. The active ingredient in licorice root, glycyrrhizinic acid has been linked to small, clinically non-significant decreases in testosterone levels.[115] In contrast, a more recent study found that licorice administration produced a substantial testosterone decrease in a small, female-only sample.[116]
- Natural or man-made antiandrogens including spearmint tea reduce testosterone levels.[117][118][119]
