Is Timing Important? The Role of Diet and Lifestyle during Early Life on Colorectal Neoplasia.

Purpose of the review: To summarize the current evidence on the most important dietary and lifestyle factors in colorectal carcinogenesis during different stages of a lifetime with special emphasis on studies investigating exposure during childhood, adolescence and young adulthood.

Recent findings: A number of studies showed that independent of adult obesity, higher body fatness during childhood, adolescence and young adulthood is associated with risk of colorectal cancer later in life. In one large cohort study, the Nurses' Health Study II, adherence to a western pattern diet during adolescence was associated with higher risk of advanced adenoma. The current evidence relating consumption of individual foods and nutrients as well as physical activity during early life to colorectal cancer is sparse and less consistent, at least in part due to limitations in study design, such as sample size, limited data on potential confounders or lack of a validated dietary assessment instrument.

Summary: As colorectal carcinogenesis is a long process and can take up to several decades to develop, early life risk factors may also be etiologically relevant. The recent rise in early-onset colorectal cancer incidence and mortality in the US, i.e., in individuals younger than 55 years at diagnosis, strongly supports that early life risk factors may influence colorectal carcinogenesis. Considering that the majority of colorectal cancers are preventable, there is an urgent need for well-designed investigations on the role of diet and lifestyle factors throughout the life course and risk of colorectal cancers.