So that’s what makes Popeye strong! Spinach found to boost key protein in muscles

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UPDATED:

16:00 GMT, 25 June 2012

Popeye eating spinach

Spinach DOES boost your muscles – thanks to the high level of nitrate

Spinach really does give us extra strength, scientists say, but it's not because it is full of iron.

For although the green leafy vegetable does have high levels of the nutrient it also contains a substance that makes it harder for the body to absorb it.

Instead a team from Karolinska Institutet, in Sweden, found that it is the high level of nitrate in spinach that helps build up the biceps.

They found mice supplied with nitrate in their drinking water developed significantly stronger muscles by stimulating two key proteins.

The quantity of nitrate that the mice received was roughly equivalent to that which a person would obtain by eating 200 to 300 grams of fresh spinach or two to three beetroots a day.

The researchers divided the mice into two groups, one which was given nitrate in their drinking water for seven days and a control. While spinach and beetroot are two of the main sources of nitrate, it also occurs naturally in many other leafy vegetables, such as lettuce and chard.

A week into the experiment the team examined different muscles on the mice’s legs and feet.

They found that the mice that had been on consistent nitrate had much stronger muscles, the greatest effect being observed in the extensor digitorum longus muscle, which extends down the tibia, and the flexor digitorum brevis muscle of the foot.

Continuing their study, the researchers then discovered that the nitrate mice had a higher concentration of two different proteins in their muscles, which is assumed to explain the greater muscle strength.

Eating more green leafy vegetables like spinach may help build up the muscles

Eating more green leafy vegetables like spinach may help build up the muscles

The teams now want to take their discoveries further and study how they can be applied to people with muscle weakness.

'From a nutritional perspective our study is interesting because the amount of nitrate that affected muscle strength in mice was relatively low,' says Dr Andrs Hernndez, researcher at the Department of Physiology and Pharmacology.

'Translated to humans it means that we can obtain the equivalent volume by eating more of a vegetarian diet, as nitrate is found naturally in several leafy vegetables, especially in beetroot juice, for example. There are currently no dietary supplements containing nitrate.'