Beetroot has become something of a nutritional celebrity in recent years. From athletes drinking beetroot juice before exercise to people using concentrated beetroot supplements for their blood pressure, this rather humble root vegetable has attracted an extraordinary amount of scientific attention.

And much of that interest centres on one fascinating molecule: nitric oxide.

We know that dietary nitrate, found naturally in beetroot and certain leafy green vegetables, can influence nitric oxide production in the body. Because nitric oxide plays an important role in blood vessel function, researchers have also become interested in whether increasing its availability might improve other aspects of metabolic health, including blood sugar regulation.

A new systematic review examining six randomised controlled trials has revisited this question. And it provides an excellent opportunity to explore an important distinction in nutritional science: just because a food influences a biological pathway doesn't necessarily mean it improves every health outcome connected with that pathway.

What Makes Beetroot So Interesting?

Beetroot is naturally rich in inorganic nitrate, a compound that participates in a rather remarkable physiological process.

When we eat nitrate-rich foods, nitrate is absorbed into the bloodstream. Some of it is then concentrated in our saliva, where bacteria living in the mouth convert it into nitrite.

Once swallowed, nitrite can undergo further chemical reactions, eventually contributing to the production of nitric oxide.

This is known as the nitrate–nitrite–nitric oxide pathway, and it's one of the reasons the bacteria living in our mouths have attracted increasing scientific interest.

Nitric oxide itself is a short-lived signalling molecule with several important functions. One of its best-known roles involves relaxing the smooth muscle surrounding blood vessels, allowing them to widen and influencing blood pressure and circulation.

This has led to considerable research into beetroot juice and cardiovascular function, with some controlled trials demonstrating improvements in blood pressure and measures of vascular health.

But could the same mechanism influence blood sugar regulation?

What Does Nitric Oxide Have to Do With Blood Sugar?

At first glance, nitric oxide and blood glucose might seem like completely separate subjects. However, there are several interesting connections between them.

One involves the delivery of glucose and insulin to skeletal muscle.

Skeletal muscle is responsible for a substantial proportion of the glucose removed from the bloodstream after eating. For insulin to stimulate glucose uptake effectively, glucose and insulin must first reach the muscle tissue through its blood supply.

Nitric oxide contributes to vascular regulation, including processes that influence blood flow through small blood vessels. Researchers have therefore proposed that improving nitric oxide availability might support the delivery of insulin and glucose to metabolically active tissues.

There are also experimental findings suggesting that nitric oxide signalling interacts with mitochondrial function and cellular metabolism.

Taken together, these mechanisms provide a plausible reason to investigate whether dietary nitrate could influence insulin sensitivity and glucose regulation.

But plausible is the important word here.

A mechanism that makes sense biochemically doesn't automatically establish that consuming more beetroot will meaningfully improve blood sugar control in humans.

What Have the Human Trials Found?

The new systematic review by Jamshidi and colleagues examined six randomised controlled trials investigating beetroot-derived nitrate or nitrite preparations and measures of glycaemic control.

These outcomes are particularly relevant because blood sugar regulation involves several related but distinct processes.

Fasting blood glucose provides a snapshot of circulating glucose after a period without food. HbA1c reflects average glucose exposure over approximately two to three months, while fasting insulin and measures such as HOMA-IR can provide additional information about insulin regulation.

The wider clinical trial evidence has so far been mixed, with several studies failing to demonstrate significant improvements in these outcomes despite the biological rationale for nitrate supplementation.

For example, a 24-week randomised trial involving people with type 2 diabetes found that nitrate-rich beetroot supplementation did not significantly improve glucose, HbA1c, insulin or calculated insulin resistance compared with placebo.

Another 12-week trial using concentrated beetroot juice in people with type 2 diabetes similarly found no significant improvements in the main measures of glycaemic control.

These findings don't establish that dietary nitrate has no metabolic effects. They do, however, suggest that increasing nitrate intake isn't necessarily enough to produce a clinically meaningful improvement in blood sugar regulation.

And that's a very different conclusion from simply assuming that more nitric oxide must mean better insulin sensitivity.

Why Might the Results Be Inconsistent?

There are several possible explanations.

First, the trials have differed in their participants, doses, supplement formulations and duration. A short intervention in healthy adults may produce different results from a longer study involving people with established type 2 diabetes.

Second, insulin resistance is an extremely complex physiological problem. It involves interactions between skeletal muscle, the liver, adipose tissue, pancreatic function and numerous cellular signalling pathways.

Improving one aspect of vascular function may not be sufficient to overcome disturbances occurring elsewhere in the metabolic system.

There's also the question of how efficiently individuals convert dietary nitrate into nitrite and nitric oxide. Oral bacteria play an important role in this process, meaning differences in oral microbiology could potentially influence responses to nitrate-rich foods.

These are reasonable explanations to investigate, although we shouldn't assume that any one of them accounts for the inconsistent clinical findings.

Does This Mean Beetroot Isn't Worth Eating?

Absolutely not. Beetroot remains a nutritious vegetable, providing fibre, folate, potassium and a range of phytochemicals, including the betalain pigments responsible for its distinctive colour.

It can contribute to a varied, plant-rich dietary pattern, and the research into dietary nitrate and vascular function remains genuinely interesting.

But there's a difference between recommending beetroot as part of a healthy diet and recommending concentrated beetroot supplements as a treatment for insulin resistance or type 2 diabetes.

At present, the evidence doesn't justify treating beetroot supplementation as an established strategy for improving glycaemic control.

If the goal is better blood sugar regulation, we have much stronger evidence supporting regular physical activity, maintaining healthy skeletal muscle, improving overall dietary quality and addressing excess body fat where appropriate.

Those approaches influence multiple aspects of metabolic physiology rather than relying on a single signalling pathway.

The Bigger Lesson From This Research

For me, this is what makes nutritional biochemistry so fascinating.

We can identify a compound in a food, understand how it's absorbed, trace its conversion into another molecule and demonstrate effects on particular physiological pathways.

But that still doesn't tell us everything about what happens when somebody consumes that food over weeks, months or years.

The body is an extraordinarily complicated system, and changes in one pathway don't necessarily translate into improvements across every related aspect of health.

Beetroot may influence nitric oxide availability, and nitric oxide certainly has important roles in cardiovascular and metabolic physiology.

But influencing a biological mechanism and demonstrating a meaningful clinical benefit are two very different things.

And understanding that distinction is essential if we want to make sensible decisions about nutrition rather than chasing every promising new compound.

References

Jamshidi, A., Tangestani, H., Yari, Z. et al. (2026) ‘The effect of dietary nitrite/nitrate on glycaemic control: a systematic review of randomized controlled trials using beetroot-derived preparations’, Nutrition & Metabolism. https://doi.org/10.1186/s12986-026-01231-z

‘Effect of inorganic nitrate on metabolic parameters in patients with type 2 diabetes: a 24-week randomized double-blind placebo-controlled clinical trial’ (2021). https://www.sciencedirect.com/science/article/pii/S1089860320302160

‘Effects of concentrated beetroot juice consumption on glycemic control, blood pressure, and lipid profile in type 2 diabetes patients: randomized clinical trial study’ (2022). https://pubmed.ncbi.nlm.nih.gov/35869311/