Lower Acid Diet May Boost Exercise Capacity, Especially in Elderly

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Eating a lower acid diet—typically lots of fruits and vegetables—may help boost exercise capacity, particularly for older patients, according to an abstract presented at Kidney Week.

Acid-producing diets, such as those rich in animal proteins, can exacerbate chronic kidney disease—so nephrologists often prescribe a low acid diet or bicarbonate supplements to balance a patient’s acid load. High acid diets may also have ill effects on otherwise healthy individuals, particularly those who are experiencing age-related renal decline.

Now, Enni-Maria Hietavala, MS, a PhD student in the laboratory of Antti Mero at the University of Jyväskylä in Finland, shows that eating a low acid diet boosts exercise capacity. In the study, 88 healthy volunteers (22 adolescents, 33 young adults, and 33 elderly individuals) were assigned to eat a high acid or a low acid diet for 7 days and then switch to the other diet. At the end of each week, the participants were monitored as they performed a strenuous cycling test and provided blood samples.

The study found that base levels in the body declined for all participants during the high acid diet. Base levels were lower in both young and elderly women who performed suboptimally on the cycling test after eating the high acid diet. In young women, the maximum exercise workload was 19% shorter and the maximum cardiorespiratory capacity was lower after eating the high acid diet compared with the low acid diet.

Previously, Hietavala, MS, and her colleagues published a study showing that older people are more sensitive to the ill effects of a high acid diet on their exercise capacity (Hietavala Em, et al. European Journal of Clinical Nutrition 2015; 69:399–404).

“When you are young your kidneys work well and you have a large base buffer capacity,” explained her co-author Lynda Frassetto, MD, an emeritus professor of nephology at the University of California-San Francisco. But as people age they become less able to compensate. The current findings, if validated, suggest that eating a low acid diet should help individuals maintain muscle and bone mass via exercise, while promoting better kidney function, Frassetto said.

Bess Dawson Hughes, MD, a professor of medicine and director of the Bone Metabolism Laboratory at Tufts University in Boston, said the study will likely trigger additional research to find out if the benefits of a low acid diet on exercise capacity are sustained over time.

Alhough it is too soon to make clinical recommendations based on the results, they may have important implications for older adults.

“This diet modification is particularly important in elders whose exercise capacity is low,” Dawson-Hughes explained. “It may enable people to have better functional capacity to live independently.”

Bicarbonate supplements have been shown to help boost exercise capacity in elite athletes in some studies (Burke LM. Nestle Nutr Inst Workshop Ser 2013; 75:15–26), and Dawson-Hughes and her colleagues have also found improved muscle power in older women given bicarbonate supplements over 3 months (Dawson-Hughes B, et al. Osteoporosis Int 2010; 21:1171–1179). The low acid diet used by Hietavala was high in fruits and vegetables. This suggests that following current dietary recommendations for fruits and vegetables may be enough to help.

“If we were to do what is recommended by the dietary guidelines, we wouldn’t have these [high] acid loads,” Dawson-Hughes said. “It’s another piece of evidence that we need those fruits and vegetables.”

“Low Dietary Acid Intake May Help the Kidneys Improve Exercise Capacity” (Oral Abstract 068)