Peripheral artery disease (PAD) is an atherosclerotic disease characterised by the build-up of plaque in the arteries supplying blood to the legs. Around 200 million people suffer from PAD worldwide, often experiencing leg pain during walking that can negatively affect their quality of life. There are few treatment options and while exercise training can help with early-stage PAD, later stages of the disease can require surgery or even amputation.
Beetroots are a dietary source of nitrates that the body converts into nitric oxide, a bioactive known to support cardiovascular health. Beetroot juice, naturally rich in nitrates, therefore has potential as a functional health drink.
Scientists from the University of Nebraska carried out a small, randomised crossover study with 10 participants to determine the impact of a moderate dose of dietary nitrates (0.11 mmol nitrate per kilo of body mass) on PAD symptoms.
They found that skeletal muscle microvascular function (assessed by reactive hyperaemia) was greater after drinking beetroot juice compared to the placebo group. Post-exercise recovery also occurred at a faster rate and participants who drank beetroot juice were able to walk further in six minutes although there were no changes in heart rate variability or pain-free walking distance.
A natural solution with no known side effects
According to lead scientist Elizabeth Pekas, the study builds on previous research from 2021, which found that a moderate dose of dietary nitrate in the form of beetroot juice may be an effective nutraceutical therapy to improve macrovascular function, blood pressure, and walking capacity in patients with PAD.
However, the 2021 study did not investigate the potential effects of dietary nitrate on different levels of the vasculature or macro- to microcirculation. This study confirms that the moderate dose improves microcirculatory function in the leg muscles of PAD patients.
“The current findings support our previous research and provide new insights regarding dietary nitrate in the form of beetroot juice as an effective therapeutic to support microcirculatory function and walking capacity in patients with PAD,” Pekas told Vitafoods Insights.
“Importantly, there were no known side effects associated with this dose of dietary nitrate, and the dose was well-tolerated by our study participants. Moving forward, the nutraceutical industry may use this information to potentially optimise dosing strategies for certain populations, ranging from healthy populations to those with diseases that affect the circulation.”
More research required on impact of lower-cost nutraceuticals
Nevertheless, further research is needed to understand the long-term efficacy of this proposed dose for PAD patients, Pekas said. She added that further research into the possible negative impact of cheaper, and possibly lower quality, nutraceuticals was required.
“Knowing that PAD has been reported to disproportionally affect individuals of lower socioeconomic status, it is important to investigate lower-cost nutraceutical regimens that produce minimal side effects.”
A 2014 study found that individuals in the US from the lowest of the six poverty–income ratio categories had twice the risk of developing PAD compared with those in the highest poverty–income ratio category.
Beetroot for blood pressure and cardiovascular health
Athletes often eat nitrate-rich leafy greens and beetroots to elevate their nitric oxide levels and increase endurance and performance. A 2021 study found that nitrate-rich beetroot juice improved running performance although the researchers noted that its distinct, earthy taste might act as a barrier to consumption, making supplementation a more appealing way to increase nitrate intake.
However, cardiovascular health has a wider appeal and market analysts at Mintel have identified “heart-friendly botanicals and natural ingredients” as a key area for future innovation in cardiovascular health.
“Many consumers believe in the 'power of nature' where their health is concerned. Ingredients of plant origin that are scientifically proven to support heart health represent an opportunity for producers in this space,” analysts wrote in a 2022 report, Patent Insights: Cardiovascular health.
The report highlights a steady increase in published patents targeting cardiovascular health in recent years, with a key area of patent innovation including natural, botanical ingredients that support heart health.
One such patent by Berkeley Nox describes a “cardio-protective” food supplement with beetroot extract containing betaine nitrate; potassium nitrate; green coffee bean; and pomegranate fruit extract. According to the patent, this mix modifies nitric oxide levels to improve hypertension, glaucoma, and cardiac heath, and improves functional nitric oxide levels in individuals.