Diet, acid-base status and the performance of high intensity exercise
The aim of the present experiments was to investigate the effects of dietary components and composition on acid-base status. It was hoped that those dietary components which exert the greatest effect on acid-base would be identified. In a second series of experiments the role of diet-induced changes on the performance of high intensity exercise was investigated. The sodium salts of weak organic acids were administered after an overnight fast and their effects on blood acid-base status were observed. An alkalinising effect on blood and urine was observed over 3 and 24 hours respectively. In the next study the sodium salts were administered for five consecutive days; blood and urine acid-base status were measured 24 hour after ingestion. Under these circumstances the salt-induced alkalosis was only observed on urine. Blood acid-base status had, after 24 hours, returned to pre-ingestion values. The alkalinising effect on urine was sustained for as long as the sodium salts were consumed. However, upon cessation of the salt ingestion urine acid-base status had returned to the pre-ingestion values within 24 hours. In the third experiment the chronic effects of different macro nutrient intakes was investigated in two groups of matched female subjects. The omnivorous group had a higher dietary intake of protein than the vegetarian subjects. There was no biologically significant difference in blood acid-base status between the two groups. As a consequence of the higher protein intake the urinary titratable acid output of the omnivorous women was higher than that of the vegetarians. Despite the same dietary intake of calcium the omnivorous subjects had a higher urinary excretion of calcium than the vegetarians. It is thought the acidifying effect on urine from the higher protein intake of the omnivorous women was responsible for their greater urinary calcium excretion.