It isn’t entirely clear why cholesterol affects fertility but the waxy substance is key to the synthesis of sex hormones like oestrogen and testosterone in the body.
Lipids, especially cholesterol play significant role in the structural and functional activity of sperm. Excessive intake of high cholesterol or high fat diet may induce hypercholesterolemia/hyperlipidemia and disturb cholesterol homeostasis (stable internal environment) in the body which may adversely affect normal male reproductive functions. Additionally, high level of total cholesterol and low level of HDL cholesterol are important risk factors for erectile dysfunction (inability to obtain or sustain an erection). Feelings of stress, depression, guilt, or anxiety in infertile men can cause psychogenic impotence, which heightens the feelings of inadequacy that already accompany infertility. The psychological stress of infertility has been shown to affect sperm parameters in significant and demonstrable ways that may further contribute to difficulties with erectile potency; emotional reactions to the infertility may alter or even undermine a previous consolidation of a sense of self as sexually adequate.
A large number of human studies have also indicated an association between hypercholesterolemia and poor semen quality and subsequent male infertility. However, most of these studies have been conducted on normal infertile or obese men. Whether the hypercholesterolemia has any impact on sperm/seminal plasma cholesterol/lipid content is still poorly known.
The presence of high levels of LDL and low HDL is often associated with polycystic ovary syndrome (PCOS). PCOS reduces quality of life by depression, anxiety, obesity, infertility, and hirsutism (excessive body hair on parts of the body where hair is normally absent or minimal). PCOS is the most common cause of menstrual disturbance such as oligomenorrhea (infrequent menstruation), anovulation (ovaries do not release an egg during a cycle), menorrhagia (abnormally heavy and prolonged bleeding during menstruation), and infertility. Thus, natural conceiving is avoided.