Study under review: Ergogenic Effect of Nitrate Supplementation: A Systematic Review and Meta-analysis
Both athletes and recreationally active people commonly use dietary supplements in an attempt to improve their physical performance. One such supplement is nitrate (NO3−), a molecule which is produced in the body in small amounts, and which is obtainable through the diet mainly through the consumption of some vegetables (e.g., lettuce, beetroot, and spinach).
In the body, dietary nitrate is reduced to nitrite, and then to nitric oxide (NO) through what is called the nitrate-nitrite-nitric oxide pathway, shown in Figure 1. NO, through its effects on vasodilation, mitochondrial respiration, calcium handling, and glucose uptake, may improve muscle function and reduce fatigue, thereby enhancing physical performance.
Reference: Jones. Sports Med. 2014 May.
While NO3− supplementation should, theoretically, improve training performance, there is substantial variability in its ergogenic effects within and between trials. This variability could be due to several factors, including biological sex, aerobic fitness level, environmental oxygen concentrations, exercise parameters, and the dosage and timing of NO3− supplementation. The meta-analysis under review pooled the available trials together to examine the overall impact of nitrate supplementation on training performance, and is the first meta-analysis to have examined the potential influence of the aforementioned factors on NO3− ergogenicity.
Although nitrate supplementation is common in athletes and recreationally active people looking to improve their physical performance, there is substantial variability in the ergogenic effects of nitrate within and between trials. This variability could be due to several individual, environmental, exercise, and supplementation-related factors. The meta-analysis under review aimed to examine the potential influence of these factors.
Other Articles in Issue #74 (December 2020)
Deep Dive: Comparing different protein sources' impact on bone turnover
Eating more plants can be healthy but may negatively impact bone health due to lower protein, calcium, and vitamin D intake. This trial examined how the same amount of protein from animal or plant sources affected bone turnover.
Deep Dive: Does low protein intake slow down chronic kidney disease progression?
Very low protein diets seem to slow progression but don't affect mortality, raising the question of whether there's a risk-benefit tradeoff. Higher quality, larger trials could shed more light on this issue.
Deep Dive: How does alternate-day fasting compare to no diet or other diets?
ADF helps people lose weight and lower cholesterol, but there's no clear advantage over continuous energy restriction based on the current evidence. Larger, longer studies are needed, though.
Mini: Dietary approaches and supplements to combat chronic pain
What nutritional interventions impact different chronic pain conditions? This NERD Mini summarizes the evidence from a systematic review released earlier this year.
Interview: Jeff Rothschild, RD, CSSD, PhD(c)
What should we eat before exercise? To find out, we picked the lead author's brain of a recent review that answers that exact question!
Deep Dive: Determining the per-kilogram effects of weight loss on lipid levels
How much do blood lipids change for each kilogram of weight lost? This study aimed to answer this question, while also exploring whether the method of weight loss (through lifestyle, drugs, or bariatric surgery) matters much.
Deep Dive: The best non-drug ways to lower blood pressure
Drugs are usually an effective way to lower blood pressure, but non-drug interventions can help a lot, too! This network meta-analysis looked at which non-drug methods are the best for lowering blood pressure.