Exercise, diet, or physical characteristics as determinants of HDL-levels in endurance athletes

Serum lipids, lipoproteins, apolipoproteins, physical characteristics, and 10-day dietary records of 20 male distance runners (aged 20-42 years) were compared with those of 14 sedentary controls (aged 23-34 years). Runners had significantly greater levels (mean +/- SD) of high density lipoproteins (HDL) whether estimated as HDL-cholesterol (66 +/- 12 vs 46 +/- 10 mg/dl) or as the major HDL apolipoproteins, apoA-I (170 +/- 36 vs 124 +/- 27 mg/dl) or apoA-II (39 +/- 5 vs 34 +/- 4 mg/dl). Runners were leaner with considerably less body fat (8.3 +/- 1.7 vs 16.2 +/- 3.9%) than the sedentary men despite consuming 20% more calories. Moreover, the additional calories consumed were largely carbohydrate. This comparison illustrates that high absolute quantities of dietary carbohydrate do not depress HDL levels in lean individuals engaged in exercise training. Furthermore, the results suggest that dietary factors may be as important as exercise itself in producing the lipoprotein pattern characteristic of endurance athletes.