Written by Joyce Smith, BS. This study provides preliminary evidence that dietary inorganic nitrate supplementation, alone or in combination with folic acid, significantly reduced blood pressure in hypertensive adults from Tanzania, Africa.
According to 2010 statistics, almost two-thirds of the population worldwide are hypertensive 1. Twenty-nine percent of residents in high-income countries and 31.5% in low and middle-income countries have hypertension 1. Hypertension affects, 46% of adults in the Sub-Saharan region of Africa 2 and is the sixth leading cause of disability 3. Hypertension is associated with an increased risk of stroke, ischemic heart disease, chronic kidney disease, and neurodegeneration, and is a major contributor toward disability and premature mortality 3. Health care challenges, including the diagnosis and treatment of hypertension, has led to the exploration of a diet-based intervention as an alternative to costly medications 4. Inorganic nitrate, a precursor to nitric oxide, and folic acid are found in relatively high levels in certain leafy green vegetables and in beetroots 5. Existing literature suggests both beet root extracts and folic acid have a potential role in the control of hypertension and endothelial function 6 and although nitrates and folic acid have different mechanisms of operation, combining the two may provide better control of hypertension.
To explore this hypothesis, 7 Siervo and colleagues conducted a feasibility study to determine the effects of dietary inorganic nitrate supplementation, alone or in combination with folic acid supplementation, on the BP of a group of Tanzanian adults with elevated BP. Forty-seven middle-aged and older participants (age: 50–70 y, BMI: 26.3–29.1 kg/m2) were randomly allocated to three groups assigned to a 60-day supplementation of the following:
- Group one (N+F): 400 mg high-nitrate beetroot juice and 5 mg of folic acid
- Group two (N+P): 400 mg of high-nitrate beetroot juice and a sucrose powder placebo
- Group three (P+P): 400 mg of nitrate-depleted beetroot juice and a sucrose powder placebo
Clinical and 24-hour ambulatory and resting clinic BP, plasma homocysteine, C-reactive protein (CRP), folate, nitrate, salivary nitrate (using salivary strips), and nitrite concentrations were all measured at baseline and repeated at thirty and sixty days.
Mean baseline resting systolic and diastolic BP was 151.0 ± 19.4 mm Hg and 91.8 ± 11.7 mm Hg, respectively. A significant increase in nitrate and folic acid concentrations in plasma and saliva samples was seen in the treatment arms, implying that intervention compliance was high (>90% of all participants reported taking supplements regularly). After 60 days, 24-hour systolic BP significantly decreased by −10.8 ± 9.8 mm Hg (P < 0.001) in the N+P group and by −6.1 ± 13.2 mm Hg (P = 0.03) in the N+F group, but not significantly in the P+P group (−0.3 ± 9.7 mm Hg (P = 0.83). While all three groups had 24-h diastolic BP reductions, only the N+P group had a significant decrease in 24-h diastolic BP (−5.4 ± 5.0 mm Hg, P = 0.004).
This study validates previous research on the benefits of salivary strips for determining nitrate consumption in a low-income population. The authors concluded that high-nitrate beetroot juice may serve as an inexpensive therapy to reduce hypertension in low-income countries. They recommend longer-term studies to further explore the ability of dietary nitrate to reduce BP and cardiovascular risk, particularly in these countries.
Source: Siervo, Mario, Oliver Shannon, Navneet Kandhari, Meghna Prabhakar, William Fostier, Christina Köchl, Jane Rogathi et al. “Nitrate-rich beetroot juice reduces blood pressure in Tanzanian adults with elevated blood pressure: a double-blind randomized controlled feasibility trial.” The Journal of Nutrition 150, no. 9 (2020): 2460-2468.
© The Author(s) on behalf of the American Society for Nutrition 2020. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/).
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Posted October 26, 2020.
Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.
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- Mokgobi MG. Towards integration of traditional healing and western healing: Is this a remote possibility? African journal for physical health education, recreation, and dance. 2013;2013(Suppl 1):47-57.
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- Siervo M, Shannon O, Kandhari N, et al. Nitrate-Rich Beetroot Juice Reduces Blood Pressure in Tanzanian Adults with Elevated Blood Pressure: A Double-Blind Randomized Controlled Feasibility Trial. J Nutr. 2020;150(9):2460-2468.
