A 2008 study in the journal “Cancer, Epidemiology, Biomarkers, and Prevention” analyzed the link between a breast cancer gene, coffee consumption, and breast size. It proceeded to incite a ridiculous hysteria in the media with headlines like, “Drinking three cups of coffee a day shrinks women’s breasts” and my punny personal favorite, “Women Face Drink & Shrink Dilemma: Coffee Poses a Booby Trap.” However, as is common with science portrayals in the media, many headlines/articles mistake correlation for causation. In addition, many articles completely leave out the genetic, breast cancer aspect of the study, as “CYP1A2 gene” doesn’t exactly scream “headline material”. But the gene is an important thing to note when analyzing the study, because although there was a slight negative correlation of breast size and coffee consumption for people with the gene, people without the gene had a slight positive correlation. In addition, the word “shrink” implies a change over time but the study was cross-sectional, not longitudinal. It only took data from a single point in time. There is no mention of “shrinkage” in the paper or change in breast size (unless related to breast cancer, an entirely different can of worms). Finally, they measure breast size using the formula for pyramids, base area x height, divided by 3, rather unrealistic, in my personal experience.
The most annoying aspect to me is that the article attempts to be scientific, with statements like, “Some substances in coffee can change a woman’s metabolism so she acquires a better configuration of various estrogens, therefore lowering the potential risk.” But if you want to be actually scientific, maybe read the original journal article in the first place.