There are quite a few scientific studies that compare vegans and vegetarians to meat eaters concerning the health effects of their diet. The most common comparisons involve all cause death, cardiac death or cancer. Most of these studies do not consider the components of the diet, such as high potassium foods, high protein foods or foods with saturated fat.
A study from a few years ago (1) combined 5 studies to look at 76,172 people. It broke the groups into more than the usual vegan versus non-vegetarian groups. The groups they examined separately were vegans, occasional meat eaters, meat eaters, lactoovovegetarians, and fish eating vegetarians (pescatarians). Compared to the meat eaters, the occasional meat eaters had a lower mortality, and the vegans next lowest. The lowest however were the lactoovovegetarians and the pescatarians.
Mortality from ischemic heart disease was the main factor distinguishing one group from another. Compared to regular meat eaters, ischemic heart disease mortality was 20% lower in occasional meat eaters, 26% lower in vegans, 34% lower in lactoovovegetarians, and 34% lower in those eating fish but not meat.
What is interesting is that these very same studies had been combined in a previous report (2). The 76,172 participants were divided differently. They were simply divided into vegans, meat eaters, and occasional meat eaters (which included the fish eaters and lactoovovegetarians). The vegans did the best, the meat eaters the worst and the occasional meat eaters in between. The advantages of eating fish and milk and eggs were hidden by lumping the people who ate these foods with the occasional meat eaters.
These two reports point out the danger of overinterpreting studies. From the study dividing the larger group into 3 groups we might conclude that eating any animal product is harmful. The other study using the very same people as in the first study shows how wrong that conclusion would be.
Generally, the more aspects of a subject that you are able to examine, the more information you can get. Most fish and dairy will provide more potassium, protein and other nutrients important to health, while leaving out saturated fat, sodium and other undesirable food components. By lumping these foods with meat, their advantages will not be noticed. To find tables with some of the nutrient values of these foods, including potassium, go to the “Links To Food Potassium Tables” tab at the top of the page to find tables for other food categories.
1. Mortality in vegetarians and nonvegetarians: detailed findings from a collaborative analysis of 5 prospective studies. Key TJ, Fraser GE, Thorogood M, Appleby PN, Beral V, Reeves G, Burr ML, Chang-Claude J, Frentzel-Beyme R, Kuzma JW, Mann J, McPherson K. Am J Clin Nutr. 1999 Sep;70(3 Suppl):516S-524S. PMID:10479225
2. Mortality in vegetarians and non-vegetarians: a collaborative analysis of 8300 deaths among 76,000 men and women in five prospective studies. Key TJ, Fraser GE, Thorogood M, Appleby PN, Beral V, Reeves G, Burr ML, Chang-Claude J, Frentzel-Beyme R, Kuzma JW, Mann J, McPherson K. Public Health Nutr. 1998 Mar;1(1):33-41. PMID:10555529 (abstract)