TLDR/PSA: This isn’t really a post about examining the efficacy of beetroot supplementation. Rather, it’s more of a PSA for active women & coaches of active women that the nutrition guidelines you frequently read, hear, or are told, may not always be applicable to active women.

Examine.com recently published an excellent summary of a small, but important research study on nitrate (i.e. beetroot) supplementation & exercise economy and endurance capacity in young women (1, 2). Interesting research study given there is widely held belief among athletes, coaches and even researchers that beetroot supplementation provides ergogenic or performance benefits. Case in point, an abstract of a recent systematic review in Nutrients examining a combination of the ergogenic effects of beetroot & other supplements stated unequivocally that “beetroot juice stands out as an ergogenic aid to improve sports performance, given its demonstrated influence on both aerobic and anaerobic exercise”(3). Sounds like this a supplement all athletes should consider but unfortunately, the research doesn’t necessarily bear that out. In fact, it was acknowledged in a recent systematic review that there are sex differences in response to beetroot supplementation need additional research (similar to the findings of a study published in 2019) (4,5).

But whether beetroot supplementation is ergogenic is not what I wanted to highlight but rather to use these data as an example to discuss the state of research on active women & to question whether it makes sense to apply research based primarily on men to women. So, let’s start with some stats to set the context of the state of the sports & exercise science research on women:

• 6% of sport & exercise science research is based solely on women (6)
• 4% (of 937) studies on acute carbohydrate intake were based solely on women & 2% studied sex differences (7)
• 0-6% of sports supplement research (range depends on the supplement studied) (8)
• 6.1% of heat adaptation research (9)
• 7% of sports & exercise psychology research (10)

Even if you read Christine Yu’s outstanding book Up to Speed which highlighted some of these gaps, it’s still shocking to see the stark state of the research. But why is this gap in research important? It’s well-established that there are significant sex differences across a spectrum of physiological functions (11). For example, if we look at what fuels the body uses during exercise (known as substrate utilization), women have a higher predisposition to using fat relative to carbohydrate relative to men (12). So, if women’s substrate utilization is foundationally different during exercise and sex differences & female specific response to carbohydrate supplementation haven’t been examined to the detail it has in men, is it ok to assume she needs 60-90g or more carbohydrates/hour for her training sessions (or would benefit from beetroot supplementation, etc.)?

So instead of generalizing the research guidelines, start by asking the question “does this guideline/recommendation apply to active women/me?” While we may not know the answer just yet, it’s important to be aware of the context and keep asking questions (and test it yourself/your athletes!) to support & progress research to close the gaps in understanding what works/doesn’t work for active women.  

One of the Nutrify guiding principles is to ensure our clients’ personalized recommendations are based on the best available scientific research and evidence-based recommendations for active women. We stay on top of the latest research so you don’t have to. Need help dialing in your nutrition strategy to reflect your specific needs? Schedule a complimentary information call to learn more.

References

(1) Does nitrate supplementation worsen endurance capacity in women? original paper. Examine. (n.d.). https://examine.com/research-feed/study/1vXvX9/

(2) The effects of inorganic nitrate supplementation on exercise economy and endurance capacity across the menstrual cycle. Austin C. Hogwood, Joaquin Ortiz de Zevallos, Ka’eo Kruse, Jeison De Guzman, Meredith Buckley, Arthur Weltman, and Jason D. Allen. Journal of Applied Physiology 2023 135:5, 1167-1175

(3) Ferrada-Contreras E, Bonomini-Gnutzmann R, Jorquera-Aguilera C, MacmiIlan Kuthe N, Peña-Jorquera H, Rodríguez-Rodríguez F. Does Co-Supplementation with Beetroot Juice and Other Nutritional Supplements Positively Impact Sports Performance?: A Systematic Review. Nutrients. 2023; 15(22):4838. https://doi.org/10.3390/nu15224838

(4) Senefeld, J. W., Wiggins, C. C., Regimbal R. J., Dominelli, P. B., Baker, S. E., & Joyner, M. J. (2020). Ergogenic effect of nitrate supplementation: A systematic review and meta-analysis. Medicine & Science in Sports & Exercise, 52(10), 2250–2261. https://doi.org/10.1249/mss.0000000000002363

(5) Wickham KA, Spriet LL. No longer beeting around the bush: a review of potential sex differences with dietary nitrate supplementation ¹. Appl Physiol Nutr Metab. 2019 Sep;44(9):915-924. doi: 10.1139/apnm-2019-0063. Epub 2019 Jul 26. PMID: 31348674.

(6) Cowley, E.S., Olenick, A.A., McNulty, K.L., & Ross, E.Z. (2021). “Invisible sportswomen”: The sex data gap in sport and exercise science research. Women in Sport and Physical Activity Journal, 29(2), 146–151.

(7) Kuikman MA, Smith ES, McKay AKA, Ackerman KE, Harris R, Elliott-Sale KJ, Stellingwerff T, Burke LM. Fueling the Female Athlete: Auditing Her Representation in Studies of Acute Carbohydrate Intake for Exercise. Med Sci Sports Exerc. 2023 Mar 1;55(3):569-580. doi: 10.1249/MSS.0000000000003056. Epub 2022 Oct 13. PMID: 36251373; PMCID: PMC9924969.

(8) Smith ES, McKay AKA, Kuikman M, Ackerman KE, Harris R, Elliott-Sale KJ, Stellingwerff T, Burke LM. Auditing the Representation of Female Versus Male Athletes in Sports Science and Sports Medicine Research: Evidence-Based Performance Supplements. Nutrients. 2022; 14(5):953. https://doi.org/10.3390/nu14050953

(9) Kelly, M. K., Smith, E. S., Brown, H. A., Jardine, W. T., Convit, L., Bowe, S. J., Condo, D., Guy, J. H., Burke, L. M., Périard, J. D., Snipe, R. M., Snow, R. J., & Carr, A. J. (2024). Auditing the Representation of Females Versus Males in Heat Adaptation Research. International Journal of Sport Nutrition and Exercise Metabolism (published online ahead of print 2024). Retrieved from https://doi.org/10.1123/ijsnem.2023-0186

(10) Courtney C. Walton, Kate Gwyther, Caroline X. Gao, Rosemary Purcell & Simon M. Rice (2022) Evidence of gender imbalance across samples in sport and exercise psychology, International Review of Sport and Exercise Psychology, DOI: 10.1080/1750984X.2022.2150981

(11) Neigh, G. N., & Mitzelfelt, M. M. (2016). Sex differences in physiology. Elsevier/AP.

(12) Montero, D., Madsen, K., Meinild‐Lundby, A., Edin, F., & Lundby, C. (2018). Sexual dimorphism of substrate utilization: Differences in skeletal muscle mitochondrial volume density and function. Experimental Physiology, 103(6), 851–859. https://doi.org/10.1113/ep087007

(13) Elliott-Sale KJ, Minahan CL, de Jonge XAKJ, Ackerman KE, Sipilä S, Constantini NW, Lebrun CM, Hackney AC. Methodological Considerations for Studies in Sport and Exercise Science with Women as Participants: A Working Guide for Standards of Practice for Research on Women. Sports Med. 2021 May;51(5):843-861. doi: 10.1007/s40279-021-01435-8. Epub 2021 Mar 16. PMID: 33725341; PMCID: PMC8053180.