Background: Prospective studies in US women have suggested an inverse relation between dietary protein and risk of ischemic heart disease (IHD). However, no large-scale prospective studies have been conducted in US men.

Objective: The objective was to examine the association between dietary protein and risk of IHD in a prospective study of US men.

Design: Intakes of protein and other nutrients were assessed by using a validated food-frequency questionnaire at 4 time points during follow-up of 43,960 men participating in the Health Professionals Follow-Up Study. Cox proportional hazards models were used to calculate multivariable-adjusted relative risks (RRs) and 95% CIs.

Results: During 18 y of follow-up, we documented 2959 incident cases of IHD. The RR of IHD was 1.08 (95% CI: 0.95, 1.23; P for trend = 0.30) comparing the top with the bottom quintile of percentage of energy from total protein. RRs for animal and vegetable protein were 1.11 (95% CI: 0.97, 1.28; P for trend = 0.18) and 0.93 (95% CI: 0.78, 1.12; P for trend = 0.49), respectively. When the population was restricted to "healthy" men (those free of hypertension, hypercholesterolemia, and diabetes at baseline), the RR of IHD was 1.21 (95% CI: 1.01, 1.44; P for trend = 0.02) for total protein, 1.25 (95% CI: 1.04, 1.51; P for trend = 0.02) for animal protein, and 0.93 (95% CI: 0.72, 1.19; P for trend = 0.65) for vegetable protein.

Conclusions: We observed no association between dietary protein and risk of total IHD in this group of men aged 40–75 y. However, higher intake of animal protein may be associated with an increased risk of IHD in "healthy" men.

http://www.ajcn.org/cgi/content/abstract/92/5/1265?etoc