Beet juice supplementation has been all the rage in the running community the last few years. It’s easy to see why – it’s totally natural, healthy, and when you down a shot of beet juice it has quite a punch! It makes you feel like you’ve really done something significant.
Now, I’m a fan of beets. Not only are they adorable, but they are rich in antioxidants, folate, manganese and fiber. Research is strongly in favor of beets as an ally in prevention of high blood pressure and heart disease and is being investigated as a possible protector against dementia as well.
Beet juice contains nitrates (not to be confused with nitrites which are used to preserve meats). These nitrates can be used by the body to increase nitric oxide (NO), which dilates blood vessels (called vasodilation) and improves oxygen consumption. Beets are pretty darn awesome for many reasons, this being just one. That increase in vasodilation and NO production is why beets have a beneficial impact on hypertension, cardiovascular risk and athletic performance.
A study on male soccer players showed beet juice supplementation not only increased sprint speed but kept heart rate lower during exertion. With an increased ability to utilize oxygen, exercise becomes easier. While there’s no absolute in science, numerous studies seem to support the role of beet juice in sports performance among well-trained and recreational athletes.
It is, however, crucial to note that as of 2018 – only 2 studies on beet juice included women, and neither of these studies reported women’s hormonal status. A woman’s estrogen levels significantly impacts dilation and constriction of blood vessels and has significant impacts in day-to-day activity. Endothelial-derived nitric oxide synthase, which controls BP response and promotes relaxation of blood vessels, is HEAVILY influenced by estrogen, so a woman’s hormonal status and whether or not she is on hormonal birth control is important to know.
1 study in early 2019 looked at endurance and resistance training on women taking oral birth control (OBC). The conclusion of this well-controlled study is that there was no performance effect despite vasodilation response. Supplementing with beet juice nitrates had no effect on time trials, aerobic capacity, or power output for women.
The supplement industry makes its recommendations based upon research that has been done on men. Men have more blood volume, hemoglobin, and lean mass than women which also impacts vasodilation response and endothelial response to beet juice, hormone differences aside.
For these reasons, and the fact estrogen increases vasodilation and can lower blood pressure, we cannot use research on beet juice done on men and apply it to women. What is observed in the field is that women who are supplementing with beet juice nitrates experience excess vasodilation and more orthostatic hypotension if supplementing with beet juice, whether they are on oral birth control or cycling naturally. This can lead to increased dizziness and fainting.
I caution all my active women about the beet juice craze and encourage them to be mindful of how they feel, especially when they hit the post-ovulation, high hormone phase of their cycle. If she is taking oral contraceptive pills, I advise against beet juice supplementation altogether. It’s just not worth the risk, given that preliminary research shows women can’t expect the same results as men do.
Have you tried beet juice? What’s your experience been?