Nitrate Supplementation, Exercise, and Kidney Function: Are There Detrimental Effects?

Area of Science:

• Exercise Physiology
• Nutritional Biochemistry
• Renal Physiology

Background:

• Dietary inorganic nitrate (NO3) supplementation is explored for enhancing endurance performance.
• Concerns exist regarding potential adverse effects of excess nitrate on kidney function.

Purpose of the Study:

• To investigate the impact of one week of inorganic nitrate (NO3) supplementation on kidney function in young male athletes.
• To assess changes in glomerular filtration rate (GFR) and various clearances during and after submaximal exercise.

Main Methods:

• Thirteen young males underwent 20-minute cycling at 85% maximal oxygen capacity.
• Subjects received either placebo or 450 mg potassium nitrate (PN) daily for seven days prior to exercise.
• Kidney function markers, including GFR and clearances for urea, creatinine, and albumin, were measured pre-exercise, post-exercise, and post-recovery.

Main Results:

• No significant differences in resting GFR or clearances were observed between placebo and nitrate groups.
• Post-exercise, urea clearance decreased significantly in both groups, while albumin output increased markedly.
• Following recovery, GFR remained elevated in the placebo group, urea clearance normalized, and albumin output/clearance remained elevated under nitrate supplementation.

Conclusions:

• One week of dietary nitrate supplementation does not appear to induce specific kidney function modifications at rest or during sustained submaximal exercise.
• The observed changes in albumin output and clearance post-exercise under nitrate supplementation warrant further investigation.