Popeye was right: spinach really does boost your muscles
Popeye's claim that "I am strong to the finish because I eat all my spinach" is scientifically correct, a study has found.
Researchers have discovered that eating a bowl of spinach a day makes your muscles "profoundly" more efficient.
They found that eating 300g of the vegetable reduced the amount of oxygen needed to power muscles by as much as five per cent when exercising.
The effect is so powerful it works after just three days.
The secret is not iron but nitrates which are abundant in the vegetable.
These chemicals make the mitochondria – the "engine rooms" of every cell – more efficient, they found.
"It is like a fuel additive for your muscles – it makes them run much more smoothly and efficiently," said the lead author Dr Eddie Weitzberg of the Karolinska Institutet in Sweden.
Dr Wietzberg, who reported his findings in the journal Cell Metabolism, fed people pure nitrate supplements – the equivalent to the amount in a plate of spinach – every day for three days.
At the beginning and end of the experiment they were made to pedal strenuously on an exercise bike while their oxygen intake was measured via a tube to the mouth
It was found that the difference in energy in take was between three and five per cent – a significant figure.
Spinach is well known as the superfood that gave Popeye the Sailor Man his bulging muscles.
The famous cartoon character, who dates back to the 1930s, pops open a can of spinach whenever he needs to get out of trouble.
Originally it was thought that the iron content of spinach made it a power-food.
Now scientists have learned that nitrates are the true energy-boosting ingredient in the vegetable.
Green leafy vegetables of all kinds are rich in the chemical which until recently was not thought to have any nutritional value.
"We know that diets rich in fruits and vegetables can help prevent cardiovascular disease and diabetes, but the active nutrients haven't been clear," said Dr Weitzberg.
"It is a profound and significant effect. It just shows that Popeye was right."
Previously Prof Weitzberg and colleague Professor Jon Lundberg showed that dietary nitrate increases levels of nitric oxide in the body with the help of friendly bacteria.
Nitric oxide is an important molecule which opens up blood vessels, lowers blood pressure, and improves circulation.
Mitochondria, like all engines, lose a lot of energy through heat loss.
The nitrate seems to stop this waste and make the cell – and so the muscle – run more efficiently.