The consumption of animal products may cause an increase of the hormone, IGF-1, which may increase both cancer risk and progression. Animal protein in particular may boost our IGF-1 production compared to plant proteins. The recent dramatic increase of hormone-dependent cancers in Japan has been speculatively linked to the steroids present in meat. Hormone replacement therapy (including bio-identical hormones) has been shown to be associated with increased risk of heart disease, stroke, pulmonary embolism, and invasive breast cancer.
Hormones in meat may affect a woman’s fertility; eating a single serving of meat per day may increase infertility risk by 30%. Cooked meat contains PhIP, a heterocyclic amine that activates estrogen receptors almost as strongly as pure estrogen. Nettle tea and lavender may also have estrogenic effects. Early onset puberty in girls may be partly due to xenoestrogens (industrial pollutants often found in meat and fish) and the hormones found in animal protein and milk. In contrast, eating soy may be associated with starting puberty 7-8 months later than girls who eat little or no soy. Mushrooms may also help prevent breast cancer by blocking estrogen production, thus decreasing the tumor’s ability to grow. All animal products contain estrogen. This may explain why, in a study of over a thousand women eating plant-based diets, vegan women had one-fifth the number of twins compared with vegetarians and omnivores.
Steroid hormones, either naturally occurring or via synthetics (estrogen implants, animal feed, etc.), are unavoidable in food of animal origin. Trace amounts of hormones may be common in the environment and have been found in the water supply.
One way to decrease levels of steroid hormones in the body may be to avoid eggs, dairy, and meat. People on plant-based diets have lower levels of IGF-1, which does not seem to affect their ability to accumulate muscle mass. Those on plant-based diets also have lower levels of adiponectin, a hormone that may contribute to cellulite. Those eating more plants hold onto more DHEA, an important hormone associated with increased longevity. A study confirmed that vegetarian women have lower levels of estradiol and therefore presumably a lower breast cancer risk due to higher fiber intake, which helps the body eliminate excess estrogen. Sex-hormone-binding globulins, which remove excess hormones from our bodies, have been found at higher levels in those eating vegetarian diets. Certain plant foods high in the hormone melatonin may help with insomnia.
Topic summary contributed by Linda.