High concentrations of IGF-I in the blood are linked to which of the following dietary habits?

High concentrations of Insulin-like Growth Factor 1 (IGF-I) in the blood are predominantly associated with the consumption of cow's milk. Cow's milk contains proteins and growth factors that can stimulate IGF-I production in the liver. The presence of lactose and casein in cow's milk is also thought to play a role in enhancing insulin secretion, which can further increase IGF-I levels.

Research has shown that dairy products, particularly those from cows, are significant contributors to elevated IGF-I levels in both children and adults. This connection is particularly noteworthy because IGF-I plays a role in growth and development, and its high levels have been linked to potential health risks, including certain cancers.

In contrast, other dietary habits listed, such as high consumption of fish or increased plant-based foods, do not have the same effect on IGF-I levels. Low dairy intake would naturally result in lower IGF-I levels since there would be less of the growth factors and proteins that promote its production. Thus, the consumption of cow's milk is the dietary habit most closely associated with high blood concentrations of IGF-I.