Abstract
Arterial stiffness is a cardiovascular risk factor that increases with age. Kyolic aged garlic extract has been shown to reduce arterial stiffness, while normalizing blood pressure, cholesterol and blood thickness. The present study hypothesized that increased flexibility of arteries could lead to slower blood flow and increased oxygen uptake and overall aerobic fitness. The present 12 week trial aimed to assess the effect of Kyolic aged garlic extract (AGE) on arterial stiffness, aerobic fitness, lactate threshold, recovery from muscle sore‑ ness and cardiovascular proteomic biomarkers in middle‑aged (40‑65 years) endurance athletes with elevated arterial stiffness. A total of 75 middle‑aged recreational endurance athletes completed the trial, after being randomly allocated for 12 weeks to either the placebo or Kyolic aged garlic extract groups: low‑dose cohort 1 (n=37), 2 capsules/day containing 1.2 g AGE powder and 1.2 mg S‑allylcysteine (SAC); and the high‑dose cohort 2 (n=38), 4 capsules/day of 2.4 g AGE powder and 2.4 mg SAC. Arterial stiffness was assessed through pulse wave velocity measurements and aerobic fitness was measured by volume‑maximal‑oxygen‑consumption (VO 2max) and lactate thresholds during high‑intensity exercise using a cycle‑ergometer‑test‑station, as well as measuring the levels of muscle fatigue and recovery time at 12 weeks compared with the baseline results. Urinary proteomic analysis was performed in a subgroup of participants and measured the levels of certain relevant proteins used as biomarkers for risk of cardiovascular events, at 12 weeks compared with baseline results. The Kyolic aged garlic extract group significantly improved their aerobic fitness, as was evidenced by increased VO 2max, increased aerobic power, higher lactate threshold‑to‑oxygen uptake, higher lactate threshold‑to‑power output and quicker recovery times compared with the placebo group. Pulse wave velocity, a measure for arterial flexibility, was improved in the Kyolic aged garlic extract group compared with the placebo. The proteomics analysis demonstrated that a subset of polypeptides associated with cardiovascular risk, such as heart attacks and stroke, decreased in the Kyolic aged garlic extract group at 12 weeks compared with the baseline, which was contrary to the effects observed in the placebo group. Therefore, the results of the present study suggested that Kyolic aged garlic extract signifi‑ cantly improved aerobic fitness, lactate threshold, recovery and cardiovascular proteomic biomarkers in middle‑aged endurance athletes within 12 weeks. The present clinical trial was regis‑ tered on 11/03/2020 at the Australian New Zealand Clinical Trial Registry (trial registration no. ACTRN12620000340932).