We have all heard that milk “does the body good,” but there is an argument that drinking too much milk may not harm the body. Research finds that older Icelandic men who reported recalling drinking large amounts of milk during their teens are 3 times more likely to be diagnosed with advanced prostate cancer compared to more moderate adolescent milk drinkers. This makes experts wonder if the puberty years, a time when the prostate matures, can also be a time of greater vulnerability.

So far, research on prostate cancer and milk intake during adolescence has yielded mixed results. One found that milk drinkers were offered some protection against the disease, while the other study saw no link between adolescent milk consumption and prostate cancer. Both projects were small and could not differentiate between early and advanced stage tumors.

However, Iceland offers a unique and perfect natural laboratory. The nation had minimal infrastructure during the beginning of the last century, so those in the central regions lived off the land, even drinking a lot of milk produced by farm animals. This drink was rare in coastal towns.

For this research, the team used data from more than 2,000 men born between 1907 and 1937 who had initially participated in a study that began during the 1960s.

During the early 2000s, the subjects had provided answers to questions about what they ate during their early and middle life for another project. Among the 463 subjects who recalled infrequently drinking milk in adolescence, only 1% had advanced prostate cancer or had died from the disease in the 25-year follow-up. The number was 3% among the 1,800 men who drank milk every day during their teens.

The difference could not be explained by how often the subjects went to the doctor, their levels of education, or what they ate. The amount of milk the men drank was unrelated to early stage tumors. And intake during the midlife years (most studies focus on these years) didn’t seem to have an impact, either.

The team feels their data is robust and that the findings point to adolescence as a sensitive time to develop prostate cancer. No such claim can be made based on a single study, so more work is required to confirm these findings and explore the mechanism behind the association.

We know that humans are the only animals in nature that drink milk after being weaned. We are also alone drinking another animal’s milk for most of our lives.

No one is suggesting that adolescent boys limit their milk intake during this time. Despite the controversy over drinking too much milk and its benefits, no one should worry about drinking it as it delivers many important nutrients to the body – an 8-ounce serving puts you on your way to getting the recommended amount of calcium, riboflavin, high protein quality and other valuable nutrients. Giving your body lots of good, natural nutrients as you grow is a smart step toward staying healthy into adulthood.