Influence of a D-aspartic Acid/Sodium Nitrate/Vitamin D3 Dietary Supplement on Physiological Parameters in Middle-aged Men: A Pilot Study

D-aspartic acid (DAA), nitrate, and vitamin D3 have received considerable attention in recent years for their potential health-enhancing properties. Using an open-label design, we evaluated the impact of a DAA/sodium nitrate/ vitamin D3 dietary supplement on blood testosterone and nitrate/nitrite, as well as subjective indicators of health, in middle-aged men. Methods: 10 overweight or obese men (mean age: 42 years) were assigned to ingest a DAA/sodium nitrate/ vitamin D3 supplement (either one or two servings per day) for 28 days. Blood total and free testosterone and nitrate/nitrite was measured before and after 14 and 28 days of supplementation. Subjective assessment of to health indicators (e.g., energy level, libido) was included at each collection time. Results: Total and free testosterone increased on average 5-10%, which was not of statistical significance (p>0.05). The response was highly variable; some men failed to respond to treatment, while men with relatively low basal testosterone values experienced increases exceeding 20%. Plasma nitrate/nitrite was increased approximately 6-10 fold after treatment with the supplement, with a trend noted for a time effect (p=0.07). Men reported a significantly better feeling following supplement use, as evidenced by a time effect for both vitality (p=0.02) and libido (p=0.04), with a trend noted for increased energy level (p=0.08) and mental outlook and mood (p=0.10). Conclusion: Twenty-eight days of treatment with a DAA/sodium nitrate/ vitamin D3 dietary supplement increased blood nitrate/nitrite and improved subjective feelings of vitality and libido in middle-aged men. In selected men with low basal testosterone values, the supplement increased circulating levels of this hormone.