“While eating spinach or other vegetables is good, there are many other foods you should be eating to promote muscle health,” says Erin Clifford, Chicago-based health coach. “Popeye got it right when he boasted that he was“ strong to the core because I eat spinach, ”she says. Research shows that nitrates in spinach can help the body regulate blood pressure and improve blood flow. In one study, healthy people who took the nitrate equivalent of 200 to 300 grams of spinach or lettuce for three days performed better on a cycling task than after taking a placebo.