Just about everybody who harks back a few decades are familiar with the famed cartoon character Popeye the Sailor Man, who downed a can of spinach to produce bulging muscles whenever he needed to get out of trouble. As researchers at the Karolinska Institutet in Swedenfound have discovered, it turns out that Popeye was right - spinach really can boost muscles.
According to the research, which was published in the February issue of the journal Cell Metabolism
, eating a bowl of spinach every day makes your muscles "profoundly" more efficient. Researchers found that eating 300g spinach reduced the amount of oxygen needed to power muscles when exercising by as much as five percent.
The ingredients which make spinach work so well are the nitrates found abundantly in spinach. Nitrates make the mitochondria, the "engine rooms" of cells, more efficient.
"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.
In the study, Dr Wietzberg fed people the pure nitrate supplements equivalent to the amount in a plate of spinach every day for three days. At the beginning and end of the experiment participants pedaled strenuously on an exercise bike while their oxygen intake was measured via a tube to the mouth. At the end of three days, the difference in energy intake was found to be between three and five per cent - which is considered to be a significant amount.
Originally it was thought that the iron content of spinach made it a power-food. Now scientists have found that it is nitrates which are the true energy-boosting ingredient found in spinach and other green leafy vegetables.
"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, who also added: "It is a profound and significant effect. It just shows that Popeye was right."
Previously Prof Weitzberg and colleague Professor Jon Lundberg demonstrated that dietary nitrate increases levels of nitric oxide in the body with the help of friendly bacteria. Nitric oxide helps open up blood vessels, lowers blood pressure, and improves circulation. Nitrates appear to help stop the loss of energy in the mitochondria due to heat loss, making the cell - and thus the muscle - more efficient.
The new study shows yet another benefit of nitrate and the nitric oxides that stem from them; however, questions do remain. While the new study results show that increased dietary nitrate can have a rather immediate effect, it is not clear what might happen in people who consume higher levels of inorganic nitrate over longer periods of time.
It is likely much healthier to consume nitrates and other beneficial items by eating fresh vegetables and plants (sorry Popeye, but canned spinach is much inferior to fresh spinach). When you get valuable nutrients from whole food sources, you not only get the natural organic form of such items, but also get all the supporting compounds found in the natural source.
Best of all would be to consume spinach and other produce which is certified organic. In addition to having far less of the common pesticides, herbicides and other chemicals found in non-organic vegetables, organic produce is usually much more nutritious - an important consideration in today's mineral-depleted soils.
As natural health authority Jon Barron noted in his book "Lessons from the Miracle Doctors", a bowl of spinach our grandmothers ate had eight times the nutrition in the typical bowl we eat today.