Big and Strong like Popeye!
Anyone who remembers the old Popeye cartoons knows canned spinach is the magical substance that makes the sailor’s biceps bulge, allowing him to overpower his larger, stronger nemesis and rescue damsels in distress. While spinach might not instantly transform a weakling into a powerlifter, research suggests it just might give muscles a boost.
That’s because spinach, and other dark green leafy vegetables, are excellent sources of nitrate. Of course, nitrates and nitrites get a bad rap because when these compounds are added to some foods, such as prepared or preserved meats (to help them maintain their bright, artificially “fresh” coloring) they can combine with other compounds in food to produce nitrosamines. Nitrosamines are a class of compounds that have been linked to increased risk of cancer.
But in recent years, experts have noted that nitrates and nitrites in fresh vegetables provide important nutrients that help muscles do their work. Intriguing research has shown that dietary nitrate has “profound effects on health and physiological responses to exercise,” say researchers at Sweden’s Karolinska Institutet. Amazingly, when mice were given plenty of nitrate in the feed, their muscles performed significantly better. “...These results show a striking effect of nitrate supplementation...in fast-twitch muscle resulting in increased force production.” One rich source of nitrate—beetroot juice—has been touted as a healthful supplement that can significantly lower blood pressure in humans.
And so, once again, we find that natural sources of a particular nutrient are not only not harmful, they’re surprisingly beneficial. Popeye had it right all along; eat your spinach if you want to stay strong.
Hernández A, Schiffer TA, Ivarsson N, Cheng AJ, Bruton JD, Lundberg JO, et al. Dietary nitrate increases tetanic [Ca2+]i and contractile force in mouse fast-twitch muscle. J Physiol. 2012 Aug 1;590(Pt 15):3575-83. doi: 10.1113/jphysiol.2012.232777. Epub 2012 Jun 11.
Hord NG, Tang Y, Bryan NS. Food sources of nitrates and nitrites: the physiologic context for potential health benefits. Am J Clin Nutr. 2009 Jul;90(1):1-10. doi: 10.3945/ajcn.2008.27131. Epub 2009 May 13.