Photo by Food Thinkers/Courtesy Flickr <a href="http://www.flickr.com/photos/foodthinkers/">http://www.flickr.com/photos/foodthinkers/</a> A great source of phosphorus and manganese, pumpkin seeds also contain protein, iron, calcium, zinc and a variety of vitamins including B, K and A. According to the American Journal of Clinical Nutrition, the zinc in these seeds has proven to help prevent osteoporosis in both men and women.