I compared the leaves of the lowly amaranth weed that grows in our gardens and along the roadsides to the cultivated spinach, swiss chard, kale, and romaine lettuce. Of the five, kale proved to be the real superfood, and romaine the distant loser, but amaranth leaves were superior to spinach and swiss chard in a number of areas. Comparing the numbers for the raw vegetables, amaranth has twice the calcium as spinach and three times as much as swiss chard. Iron, phosphorus, and B-6 are similar in all three, although spinach edges out slightly ahead in iron, but amaranth wins in the categories of potassium, vitamin C, and vitamin K. The only nutrient in which amaranth runs last is in vitamin A, but it still provides a full day’s supply. The numbers for the cooked greens show similar ratios to the raw, and who needs to read a million numbers? I think the point is clear. If we replaced some of our romaine in our salads with freshly picked amaranth leaves, we would be dramatically increasing the nutrients in our salads, and serving a mixture of spinach and amaranth would increase the nutrition of the greens. (But I must say, this research will have me serving more kale! I have had Russian kale volunteering itself all over my gardens since I first planted it years ago. I love it, as does my youngest, who rips it out of the garden and chomps on it like candy, but the rest of the family has mixed feelings about it. Yet it was significantly higher than the other greens in every nutrient I checked, except for B-6. So amaranth leaves and kale will be gracing our table more often!)
primary source: http://www.nal.usda.gov/fnic/foodcomp/search/