Some of the statements in mmmmbeer
aren't correct. Here are some corrections:
And of course, this means that vegetarians need to take care to eat the right combinations of foods to get the right combinations of partial proteins (or at least they should - many get by with ignoring this, but it is not healthy).
The myth of protein combining is just that, a myth. It is not necessary as long as you eat a variety of foods and meet your daily caloric needs. This myth was widely spread by the book Diet for a Small Planet, written by Frances Moore Lappé. Since it came out in the 70s, I believe, it has been updated by her to show that protein combining isn't necessary. The ADA (American Dietetic Association) has stated in its position papers on vegetarian diets for over a decade that food or protein combining isn't necessary. Their latest position paper, for year 2003, can be found at (http://www.eatright.org/Public/Files/veg.pdf). Skip to the "Protein" section for the information and the study cited.
First of all, even the things that are called generally labelled "bad" (e.g. fat, cholesterol) are in fact needed by the body. There are numerous myths surrounding these, as well. In the interest of brevity, I will simply state that a) even if you don't eat any fat, your body will generate it (along with some nasty ketones), because it needs it, and b) there are two types of cholesterol; the good kind helps fight the bad, and your body actually needs some of both.
All true. However, you forgot to mention a couple of things. First, cholesterol. Humans do not need cholesterol in their diet. Our liver makes 100% of the cholesterol that we need. Any that we get in our diets is excess. Eating animal products will actually raise LDL cholesterol (the "bad" one.) A vegetarian/vegan diet that is healthy and balanced will keep the overall cholesterol level at a better ratio. Which is, more HDL cholesterol (the "good" one) per part than LDL cholesterol. Of course, getting some cholesterol from the diet isn't going to give you heart disease unless your whole diet consists of meat, dairy, and eggs. Keyword: moderation.
Now, fat. Vegetarian/vegan diets are far from free of any fat. Plenty of plant based foods contain it. Again, a well balanced vegetarian/vegan diet will contain all the fat the body needs. Vegetarians/vegans need not go searching for fat from a big steak. The fat our bodies need most are the unsaturated fats. Found is leafy greens, nuts, seeds, and certain fruits such as avocados. With animal products, you'll be getting saturated fat, the stuff your body can do without (except in the case of fish). Fish contain some of the good fats our bodies needs, mainly omega-3 fatty acids.
and fish contain oils which actually fight "bad" cholesterol (this is that "good" cholesterol).
What's promoting the good cholesterol in fish are the omega-3 fatty acids in the oils, which I mentioned above.
By arbitrarily excluding meat, one removes all of these meals from their diet. It is the existence of this area that shows that vegetarianism is not, in and of itself, healthier than a diet including meat. A healthy diet can be made either way. Those concerned about their health should choose their diet on the merits of each food individually.
Even if you eliminate all animal products from your diet, there are plenty of other food sources. For every nutrient found in animal products, there are numerous plant sources containing the same nutrient or nutrients which can be converted as your body needs (with the one possible exception being B12). You are right, vegetarianism, in and of itself, isn't necessarily healthy. Neither is an omnivorous diet, in and of itself. All diets require a certain amount of planning to make sure you're eating healthily. Omnivores can be just as healthy as vegetarians, and vice versa. It all depends on how you eat.