Healthy living

Popeye was right - spinach can improve muscle fitness

Popeye was right - spinach can improve muscle fitness Nitrates linked to improved efficiency

Mothers often urge their children to eat their greens as they will help them grow up big and strong - and health experts have long echoed this sentiment as studies continue to show the benefits of eating fruit and vegetables, especially if they are green.

Now a new study published in the February issue of Cell Metabolism has found that eating vegetables such as spinach can make muscles more efficient. The researchers gave volunteers small doses of inorganic nitrate for three days and found that they consumed less oxygen when riding an exercise bike. As green vegetables such as spinach contain these nitrates this could provide some explanation for these health benefits.

Commenting on the results, study leader Eddie Weitzberg said: "We're talking about an amount of nitrate equivalent to what is found in two or three red beets or a plate of spinach. We know that diets rich in fruits and vegetables can help prevent cardiovascular disease and diabetes but the active nutrients haven't been clear. This shows inorganic nitrate as a candidate to explain those benefits."

Curiously, until recently nitrate wasn't thought to have any nutritional value at all. It has even been suggested that this component of vegetables might be toxic. But the study team had previously found that dietary nitrate feeds into a pathway that produces nitric oxide with the help of friendly bacteria found in our mouths. Nitric oxide has been known for two decades as a physiologically important molecule. It opens up our blood vessels to lower blood pressure, for instance.

Longer term effects need to be studied

Although these results show a short term benefit, more work is needed to understand the longer term effect of increased inorganic nitrate consumption. It will also be interesting to see if these benefits are seen in people suffering from conditions such as diabetes and cardiovascular disease.

Although the benefits of eating fruit and vegetables are well known and not in dispute, the actual mechanism for this health boost are unclear. The study provides an indication of how this might work.

Avoid mouthwash to see the benefits

Because the benefit of consuming inorganic nitrates is linked to its interaction with bacteria in the mouth, using strong mouthwash to soon after eating greens will negate the effect. According to Dr Weitzberg "you could block the effects of inorganic nitrate if you use a strong mouthwash or spit [instead of swallowing your saliva]. In our view, strong mouthwashes are not good if you want this system to work."

This article was published on Wed 2 February 2011

Image © Lev Dolgatsjov -

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