1.
The benefits and risks of beetroot juice consumption: a systematic review.
Zamani, H, de Joode, MEJR, Hossein, IJ, Henckens, NFT, Guggeis, MA, Berends, JE, de Kok, TMCM, van Breda, SGJ
Critical reviews in food science and nutrition. 2021;61(5):788-804
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Plain language summary
This review examined the health benefits and risks associated with beetroot juice (BRJ) from 86 studies. The nitrate contained in high amounts in BRJ increases nitric oxide (NO) levels in the body. NO has vasodilatory effects and thus reduces blood pressure and helps oxygen- and nutrient delivery to organs and muscles. Hence there has been an interest in BRJ for sports performance improvement and the prevention and treatment of cardiovascular disease. The review collected evidence of the effect of BRJ on the cardiovascular system and sports performance according to gender, trained and untrained individuals. Whilst the authors also briefly mention other health benefits of BRJ. From wider research, it is known that excess nitrate can form carcinogenic N-nitroso compounds (NOCs) in the body. Yet little is known whether this could also be a potential risk with BRJ consumption since vegetable consumption and many plant compounds generally appear to reduce the risk of cancers and can block the formation of NOCs. Hence the authors concluded that more research is needed to ensure that currently suggested dosages for BRJ do not aid NOCs production. In summary, BRJ has a beneficial effect on nitric oxide levels, oxygen consumption, blood flow, platelet aggregation, heart rate, cardiac output, blood pressure, improves sports performance and endurance and could be valuable for the management of cardiovascular disease. Yet high levels of consumption may not come without risks and more studies are needed to assess safety.
Abstract
Beetroot juice (BRJ) has become increasingly popular amongst athletes aiming to improve sport performances. BRJ contains high concentrations of nitrate, which can be converted into nitric oxide (NO) after consumption. NO has various functions in the human body, including a vasodilatory effect, which reduces blood pressure and increases oxygen- and nutrient delivery to various organs. These effects indicate that BRJ may have relevant applications in prevention and treatment of cardiovascular disease. Furthermore, the consumption of BRJ also has an impact on oxygen delivery to skeletal muscles, muscle efficiency, tolerance and endurance and may thus have a positive impact on sports performances. Aside from the beneficial aspects of BRJ consumption, there may also be potential health risks. Drinking BRJ may easily increase nitrate intake above the acceptable daily intake, which is known to stimulate the endogenous formation of N-nitroso compounds (NOC's), a class of compounds that is known to be carcinogenic and that may also induce several other adverse effects. Compared to studies on the beneficial effects, the amount of data and literature on the negative effects of BRJ is rather limited, and should be increased in order to perform a balanced risk assessment.
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Dietary flavanols improve cerebral cortical oxygenation and cognition in healthy adults.
Gratton, G, Weaver, SR, Burley, CV, Low, KA, Maclin, EL, Johns, PW, Pham, QS, Lucas, SJE, Fabiani, M, Rendeiro, C
Scientific reports. 2020;10(1):19409
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Plain language summary
Fruits and vegetables contain flavonoids that can protect against vascular diseases and cognitive ageing. Studies have shown that cocoa flavonoids can enhance the function of endothelial cells and blood vessels in peripheral arteries. This randomised, double-blinded, placebo-controlled crossover study assessed the effects of cocoa flavanols on cerebral and peripheral vascular and cognitive function. The healthy young subjects showed greater tissue oxygenation and cerebrovascular reactivity in the frontal parts of the brain during the carbon dioxide challenge after high cocoa flavonoid intervention. Furthermore, the cocoa flavonoid intervention improved cognitive and peripheral endothelial functions in healthy young subjects. Even though the mechanistic link behind the beneficial effects of flavonoids is not understood completely, the positive effects could be due to the ability of flavanols to enhance the bioavailability of circulation Nitric Oxide (NO). The study also found that flavonoids improved cognitive function in healthy individuals only when there was a high cognitive demand. Further robust studies are required to evaluate the mechanisms behind the benefits associated with acute flavonoid intake. Healthcare professionals can utilise the findings from this study to gain insight into the advantages of consuming a flavonoid-rich diet. Additionally, they can learn about the differing responses to flavanol intake between individuals.
Abstract
Cocoa flavanols protect humans against vascular disease, as evidenced by improvements in peripheral endothelial function, likely through nitric oxide signalling. Emerging evidence also suggests that flavanol-rich diets protect against cognitive aging, but mechanisms remain elusive. In a randomized double-blind within-subject acute study in healthy young adults, we link these two lines of research by showing, for the first time, that flavanol intake leads to faster and greater brain oxygenation responses to hypercapnia, as well as higher performance only when cognitive demand is high. Individual difference analyses further show that participants who benefit from flavanols intake during hypercapnia are also those who do so in the cognitive challenge. These data support the hypothesis that similar vascular mechanisms underlie both the peripheral and cerebral effects of flavanols. They further show the importance of studies combining physiological and graded cognitive challenges in young adults to investigate the actions of dietary flavanols on brain function.
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Endothelial Function is improved by Inducing Microbial Polyamine Production in the Gut: A Randomized Placebo-Controlled Trial.
Matsumoto, M, Kitada, Y, Naito, Y
Nutrients. 2019;11(5)
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Plain language summary
Endothelial dysfunction is an early warning sign for plaque formation in atherosclerosis. This study explores the Bifidobacterium animalis subsp. Lactis (Bifal) and arginine (Arg) on endothelial function in forty-four healthy subjects. The subjects were randomised to receive 100g daily of natural yoghurt containing Bifal and Arg, or a placebo, for a total of twelve weeks. In a precursor to this study, the authors found that Bifal and Arg increased the production of certain polyamines in the gut, essential to cell proliferation and inhibition of inflammation. They concluded that exogenous polyamines from foods may be of benefit to cardiovascular health. In this follow-up study they measured fecal, blood and urine samples to analyse polyamine concentration, bacterial DNA, serum polyamine, inflammatory cytokines, triglycerides and other biochemical parameters. The reactive hyperemia index (RHI), the primary outcome, was measured using endo-peripheral arterial tone (EndoPAT). The results showed that the participants who received the Bifal and Arg yoghurt saw their RHI increase from 1.50 to 1.81, suggesting that Bifal + Arg YG intake restored endothelial function to normal levels. The other biomarkers measured also suggested an improvement of vascular endothelial function with a reduction in serum platelet and triglyceride levels, two risk factors for atherosclerosis.
Abstract
Recently, it was demonstrated that spermidine-induced autophagy reduces the risk of cardiovascular disease in mice. Intestinal bacteria are a major source of polyamines, including spermidine. We previously reported that the intake of both Bifidobacterium animalis subsp. lactis (Bifal) and arginine (Arg) increases the production of putrescine, a spermidine precursor, in the gut. Here, we investigated the effects of Bifal and Arg consumption on endothelial function in healthy subjects. Healthy individuals with body mass index (BMI) near the maximum value in the "healthy" range (BMI: 25) (n = 44) were provided normal yogurt containing Bifal and Arg (Bifal + Arg YG) or placebo (normal yogurt) for 12 weeks in this randomized, double-blinded, placebo-controlled, parallel-group comparative study. The reactive hyperemia index (RHI), the primary outcome, was measured using endo-peripheral arterial tone (EndoPAT). The change in RHI from week 0 to 12 in the Bifal + Arg YG group was significantly higher than that in the placebo group, indicating that Bifal + Arg YG intake improved endothelial function. At week 12, the concentrations of fecal putrescine and serum putrescine and spermidine in the Bifal + Arg YG group were significantly higher than those in the placebo group. This study suggests that consuming Bifal + Arg YG prevents or reduces the risk of atherosclerosis.