Food restriction as a modulator of age-related changes in serum lipids.

Fischer 344 male rats were either fed ad libitum or 60% of the ad libitum intake. The restriction of food intake markedly increased the median length of life. Postabsorptive serum cholesterol and phospholipid concentrations increase in the ad libitum-fed rats with increasing age. Life-prolonging food restriction does not influence the serum levels of these lipids in young rats but delays the age-related increase in concentrations. Postabsorptive serum free fatty acid (FFA) concentrations decrease with advancing age in ad libitum-fed rats. Life-prolonging food restriction, while not affecting the serum FFA levels in young rats, delays and possibly partially prevents the age-related decrease in concentration. Food restriction lowers postabsorptive serum triglyceride levels at all ages studied. The data on serum cholesterol, phospholipids, and FFA provide further evidence that food restriction delays age-related changes in the physiological systems of rats. This delay of physiological decline may well retard the occurrence of age-related disease processes, thus prolonging life.