New research may add weight to dietary advice to include more greens
A recently published study conducted by researchers from the Universities of Cambridge and Southampton suggests that nitrate-rich vegetables like spinach, lettuce, cabbage and green beans (as well as beetroot and carrots) may help heart health. The authors propose one possible benefit is through the mechanism of nitrate ‘thinning’ the blood and protecting against heart disease.
The study looked at the effect of nitrate supplementation on the red blood cells of rats. It found that rats given nitrate had lower levels of red blood cells (which carry oxygen) compared to a control group. This was associated with a reduction in the hormone erythropoietin (EPO), which regulates red blood cells.
A potential new mechanism for veg and heart health?
In conditions of oxygen shortage, such as during critical illness or at high altitude, EPO increases, stimulating the production of more oxygen-carrying red blood cells. While red blood cells are needed to supply enough oxygen, they can also lead to an increase in the blood’s ‘viscosity’ or thickness, which may impair blood flow. There is also the risk of a blood clot developing, which can lead to serious complications, such as a heart attack, stroke or pulmonary embolism. A balance therefore needs to be met to get the optimum number of red blood cells and oxygen around the body. This study found that increasing nitrate in the diet improves the efficiency of the body’s use of oxygen, as it stops low oxygen levels causing the over-production of EPO, without compromising oxygen supply.
The authors point out that nitrate levels used on the rats in this study are readily achievable in humans via diet, through eating green leafy vegetables, and that these findings suggest simple dietary changes may offer benefit for people suffering from heart and blood vessel diseases that cause too many red blood cells to be produced.
Eat your greens, but not on the basis of this study
However, while the research is interesting, it’s a laboratory study on rats, not people, and it is misleading to extrapolate too much from such animal studies to humans. A healthy diet – including plenty of vegetables – and regular exercise are important for a healthy heart and weight. It’s always a good idea to eat up your greens. They contain a number of nutrients and phytochemicals thought to help prevent cancer and heart disease.
