For larger, more efficient muscles, looks like Popeye’s favorite food was a good choice, according to a study published in the February issue of Cell Metabolism.

After participants of the study took a small dose of inorganic nitrate – found prominently in spinach – for three days, they needed less oxygen while riding an exercise bike, due to better cell performance in muscles.

Although researchers are not advising that people take inorganic nitrate supplements, they instead are encouraging finding the nutrient by eating leafy green vegetables like spinach.

"We're talking about an amount of nitrate equivalent to what is found in two or three red beets or a plate of spinach," said Eddie Weitzberg of the Karolinska Institute in Sweden. "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."

For decades nitric oxide has been known to have significant health benefits, like opening up blood vessels to lower blood pressure. The results of the study found leafy greens also make mitochondria, which are the cells power producers in the body, more efficient.

The dietary nitrate has an immediate effect on the body, and further studies will show the effects of higher levels of the nutrient over a longer period of time.

Click here to read the full study.