Though spinach contains many important and valuable nutrients, this leafy green does not share the same overall benefits as many other leafy greens. Two of the most popular leafy greens, spinach and Swiss chard, also contain higher concentrations of oxalic acid, which may interfere with mineral absorption. These two vegetables also do not seem to have the same alkalizing benefits as other leafy greens.
There is no comprehensive guide for vegan and plant-based diets in choosing or preparing vegetables. However, in macrobiotics, we generally decrease the use of vegetables high in oxalates and increase white and green vegetables such as kale, bok choy, cabbage, leeks, broccoli, collard greens, arugula, etc. for daily use. To get the most benefit from these vegetables, we recommend using a variety of cooking styles that intensify the color and unique textures of the vegetables. Different preparations include steaming, blanching, or oil-sautéing. Cooking spinach is more beneficial than eating it raw. Popeye was definitely right about leafy greens, but may have been mistaken about the one he chose and popularized.