Bergamot and L-citrulline combo may enhance athletic performance

The research, published in Nutrients, found that the two ingredients have a synergistic effect, with improvements in athletic performance only seen when L-citrulline and bergamot were taken together in one supplement (NOMax).

Researchers from Magna Græcia University and the University Tor Vergata said the study confirms that nitric oxide donor supplementation is ineffective at improving exercise performance unless paired with agents that mitigate oxidative stress.

“Upon confirmation from extensive multicenter studies with extended follow-up periods, NOMax might represent an ideal supplement for athletes by optimizing the nitric oxide levels to support the flow of blood and oxygen to the endothelial and skeletal muscles” they wrote.

Enhancing L-citrulline

Commonly found in commercial pre-workout supplements, L-citrulline is an amino acid found in watermelon. Research shows this particular ingredient may increase nitric oxide levels, leading to vasodilation and improved blood flow.

However, oxidative impairment (i.e., when there is an imbalance between the production of reactive oxygen species and the body’s ability to neutralize them) may limit its beneficial effects.

The researchers therefore hypothesized that combining L-citrulline with a powerful antioxidant such as bergamot extract may enhance L-citrulline’s impact.

In the study, they used Bergamot Polyphenolic Fraction Gold (BPFG)—a bergamot extract that maintains the beneficial compounds of bergamot juice.

Study details

To test their hypothesis, the researchers recruited 90 male athletes (cyclists) and randomly assigned them to one of nine groups. Group one received the placebo, groups two and three received BPFG (500 mg and 1,000 mg), groups four and five received L-citrulline (1,000 mg and 2,000 mg), and groups six to nine received both ingredients at differing doses.

The intervention lasted for three months, with each participant instructed to follow an isocaloric diet supplemented with a daily dose of the placebo and/or the test products.

Blood samples were taken at baseline and after the intervention, with a standard treadmill exercise test used to measure performance.

The researchers found that three months of BPFG and L-citrulline produced a “significant synergistic effect,” markedly increasing nitric oxide release and reactive vasodilation.

Cardiorespiratory fitness also improved significantly in the combination groups, resulting in a substantially higher VO2 max and peak power, an increase in VT1 (the ‘aerobic threshold’) and VT2 (the ‘lactate threshold’), and a significantly lower heart rate.

Mitigating oxidative stress

While BPFG and L-citrulline increased nitric oxide levels in the blood, the groups taking either ingredient in isolation did not see an improvement in exercise performance. The researchers said this is likely due to BPFG’s antioxidant effects which enhance L-citrulline’s impact.

“A growing body of evidence indicates that high-intensity exercise leads to exercise-induced oxidative stress […] combining antioxidant supplements (BPFG) with citrulline supplementation can restore the mechanisms that promote a healthy nitric oxide–endothelium response, thereby improving muscle function during exercise,” they wrote.

While the results of the study are promising, the researchers warn that this was a small pilot study which lacked in long-term follow-up.

“Further research is needed to validate these findings on a larger scale, particularly regarding the potential dose–response relationship and long-term effects,” they concluded.

Source: Nutrients. doi: 10.3390/nu17071106. “The Antioxidant Power of Bergamot Polyphenolic Fraction Gold Potentiates the Effects of L-Citrulline in Athlete Performance and Vasodilation in a Pilot Study”. Authors: R. Mollace, et al.