Fibrocystic Breast Changes
The incidence of benign breast abnormalities peak in women's 30s and 40s (Sugg 2014). This is in contrast to risk of breast cancer, which continues to increase after menopause (Guray 2006).
Alcohol intake during adolescence and early adulthood increases risk of proliferative benign breast conditions (Liu 2012; Berkey 2010).
Caffeine and Related Compounds
At one time, it was believed that methylxanthines—a class of naturally occurring stimulant molecules that includes caffeine and theobromine, a compound in cacao—aggravated symptoms of fibrocystic breasts, or caused fibrocystic abnormalities to increase in size. However, a rigorous analysis of studies on the subject failed to show a beneficial effect of methylxanthine avoidance on fibrocystic changes (Franco 2013; Horner 2000). Avoidance of methylxanthines is still sometimes recommended, but the benefit for women with fibrocystic changes is uncertain (Jones 2011; Alvero 2015; Sugg 2014).