Luteinizing hormone is a gonadotropin that stimulates the testes in men and the ovaries in women. Your anterior pituitary gland secretes this important hormone, which is vital to your reproductive health. LH is a large glycoprotein made up of alpha and beta subunits. Eating or drinking caffeine-containing foods and beverages can react with LH and cause adverse effects.
Luteinizing Hormone's Physiological Effects
If you're female, luteinizing hormone stimulates ovulation. If you're male, it promotes maturation of the interstitial cells of the testes and also stimulates androgen secretion. In both males and females, LH stimulates secretion of sex steroids from your gonads. In males, this means that LH binds to receptors on your leydig cells, which in turn stimulates synthesis and secretion of testosterone. If you're female, theca cells in your ovaries respond to luteinizing hormone by producing testosterone, which is then converted into estrogen by localized granulosa cells.
Caffeine is a methylxanthine -- which simply means it acts as a diuretic that works as a smooth muscle relaxant. It also serves to stimulate your cardiac muscle as well as your central nervous system. Caffeine is also classified as a psychoactive stimulant -- which is the exact effect you may rely on to get you going early in the morning. Caffeine is an ergogenic, which increases your capacity for work and labor. Since caffeine is a drug, it can also have numerous effects on your physiology.
Luteinizing Hormone Surge
In females, ovulation of mature follicles on the ovary is induced by a large burst of luteinizing hormone commonly known as the preovulatory LH surge. Residual cells inside ovulated follicles increase rapidly in numbers to form corpora lutea, which then secrete the steroid hormones progesterone and estradiol. To maintain a pregnancy, your body requires progesterone. In addition, your corpora lutea need LH for continued development and functioning.
Caffeine's Effect on Luteinizing Hormone
Caffeine affects sex steroid hormones to varying degrees. Specifically, it increases output of luteinizing hormone while decreasing follicle-stimulating hormone. However, with prolonged use of caffeine, you will see a return of these hormones to normal baseline levels, most likely as part of an adaptive response by your body to the drug. While caffeine does increase LH surges, it can also cause issues if you are trying to become pregnant. Caffeine causes constriction of blood vessels, which can reduce blood flow to the uterus and prevent eggs from attaching to the uterine wall. While caffeine's effect on LH is pretty straightforward, women who wish to become pregnant or are pregnant should avoid it.