Examine publishes rigorous, unbiased analysis of the latest and most important nutrition and supplementation studies each month, available to all Examine Members. Click here to learn more or log in.

In this article

Red flags in study design cast doubt on soy supplementation study results

Want to know some reasons why we don't usually cover studies looking at proprietary supplement blends? Then read on.

Tags:
Study under review: Acute Soy Supplementation Improves 20-km Time Trial Performance, Power, and Speed.

Introduction

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[1] 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[2] with exercise performance, soy supplementation shows some potential as a performance-enhancer. Although a number of studies in animals[3] and humans[4] 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.

Who and what was studied

Become an Examine Member to read the full article.

Becoming an Examine Member will keep you on the cutting edge of health research with access to in-depth analyses such as this article.

You also unlock a big picture view of 400+ supplements and 600+ health topics, as well as actionable study summaries delivered to you every month across 25 health categories.

Stop wasting time and energy — we make it easy for you to stay on top of nutrition research.

Try free for two weeks

Already a member? Please login to read this article.

What were the results?

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

What does this study really tell us?

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

The big picture

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

Frequently Asked Questions

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

What should I know?

Become an Examine Member to unlock this article.

Free 2-week trial »

Already a member? Please login to read this article.

Other Articles in Issue #60 (October 2019)