Study under review: Acute Soy Supplementation Improves 20-km Time Trial Performance, Power, and Speed.
Soy contains a number of bioactive agents, including isoflavones, which are estrogen-like compounds with effects on the cardiovascular system that help to increase blood flow. As depicted in Figure 1, estrogen regulates blood flow by inducing the production of nitric oxide (NO), a potent vasodilator made by endothelial cells, a specialized cell type that lines all blood vessels. After production in the endothelium, NO diffuses into the underlying smooth muscle cells that regulate vascular tone, causing them to relax and increasing blood flow, which is called vasodilation.
Improving blood flow to working muscles during exercise has the potential to increase nutrient delivery and provide a performance-boosting edge. Since the rate of NO production has been shown to correlate with exercise performance, soy supplementation shows some potential as a performance-enhancer. Although a number of studies in animals and humans have noted that isoflavones do have an effect on the vascular endothelium, the acute effects of soy supplementation on exercise performance have only recently begun to be explored.
The study under review attempted to explore the question of whether one acute dose of soy product could provide a performance-enhancing boost during exercise.
Isoflavones can increase NO production in blood vessels, causing vasodilation and increasing blood flow. This, in turn, could improve exercise performance. The study under review examined the potential performance-boosting effects of acute isoflavone-containing soy supplementation.
Other Articles in Issue #60 (October 2019)
Vitamin D on the mind: can vitamin D help with Alzheimer's?
This randomized controlled trial suggests that supplementation has a surprisingly strong effect on aspects of cognition in people with mild Alzheimer's disease. But are the results a little too surprising?
Mini: Is vitamin D supplementation useful for pregnant women?
We've previously covered evidence suggesting that pregnant women supplementing with vitamin D have a lower risk of giving birth to babies with low birthweight. This Cochrane review suggests vitamin D may have other benefits as well.
Can vitamin D impact mortality?
This meta-analysis suggests that if it does, the effect size on all-cause mortality is pretty darn small. However, supplementation may reduce the risk of dying from cancer.
The surprisingly satiating effects of fasted cardio
Skipping breakfast before morning cardio cuts out some calories early in the day, but are those calories just consumed later on?
Does plate size matter?
Previous research looking at whether shrinking one's plate actually shrinks one's food intake has been equivocal. This well-designed study sheds some stronger light on the issue.
Supplementing spirulina for metabolic maladies
This meta-analysis synthesizes the latest evidence concerning spirulina's ability to make a dent in the metabolic syndrome.
Interview: Suzanne Robotti, Founder of MedShadow
In this interview we chat with the founder of MedShadow, a nonprofit whose mission is to provide the information needed to weigh the risks and benefits of healthcare treatments.