This is not a call to give up meat and fish entirely, but rather a happy reminder that you can supplement these categories (if not replace them, if you choose to go vegetarian -- even if only for a few days a week) with delicious items from the plant world. I like to call this the shift from "hunter" proteins to "gatherer" ones. What matters is the total protein package that a food offers, and plant-based foods deliver bonus nutrients. Beans (including soy-based items like tofu and tempeh), nuts, whole grains, wheat gluten (seitan) and other vegetable sources are good packages because, in addition to their protein content, they are low in saturated fat and high in vitamins, minerals and fiber.

What protein is, and what it does
Proteins are long chains made from 20 or so building blocks called amino acids. Your body makes proteins constantly, and because you don't store amino acids as you do fats, you need a near-daily supply of protein. Your hair, skin and muscles, the hemoglobin in your blood, and the many enzymes that keep you alive are all mostly protein. In fact, protein is the basic structural unit of our bodies. Proteins regulate fluid balance and are major components of infection-fighting antibodies, as well as many hormones. They transport nutrients in the bloodstream and are essential to bone structure and the health, maintenance and repair of muscle tissue.

Just how much protein is enough?
You need to take in about 8 grams of protein daily for every 20 pounds of your body weight. That works out to about 50 grams of protein a day for an average woman and 65 grams for an average man. Because protein is abundant in so many of the foods we normally eat, you can hit that goal pretty easily. A cup of low-fat yogurt has 11.9 grams of protein. A 6-ounce serving of roast chicken has 42.5 grams. Together, that comes to around 55 grams. A vegetarian version of this over the course of a day might be 8 ounces of firm tofu (40 grams of protein), a cup of wild rice (7 grams) and a cup of cooked chickpeas (12 grams).

Getting complete proteins
Some dietary proteins are complete -- they contain all the amino acids needed for your body to make new protein. Others are incomplete, meaning that they lack one or more essential amino acids, which your body can't produce. Meat, poultry, fish, eggs and dairy tend to be good sources of complete proteins, while vegetable protein is often incomplete. So, the more you shift away from animal sources toward plant ones, the more important it is to eat combinations that complement each other (like rice and beans, peanut butter and whole-grain bread, tofu and brown rice). It's also important to eat a good mix of beans, nuts, grains and vegetables to ensure that no essential components of protein are missing. Eat these complementary combinations either together, or within a few hours of each other.

A note to vegetarians and vegans
The lower you go on the food chain -- the more you switch from "hunter" to "gatherer" - the more you need to think about whether you're getting enough protein. If you are a lacto-ovo vegetarian and eat modest amounts of cottage cheese, low-fat milk and eggs on a regular basis, and also include in your daily diet healthy portions of soy products (like tofu and tempeh), beans, whole grains, and regular small servings of nuts, you should have no problem getting enough protein.

And if you are a vegan, here's what a day's worth of protein looks like (based on about 55 grams of protein per day):

Two Vegan Daily Protein Plans

No. 1
3 ounces cooked seitan (wheat gluten) - very high "gatherer protein" marks!
4 ounces savory baked -- or pressed -- tofu
1 cup cooked Kashi 7 Whole Grain Pilaf

No. 2
6 ounces cooked tempeh
2 tablespoons peanut butter
1 cup cooked quinoa
1 cup cooked beans

Supplement either of the above plans with five to nine servings of fruits and vegetables each day.

To sum up, here's the overall good protein point of view: Keep it varied. And keep it as plant-based as you can. Happy gathering!

Largely credited with moving healthful vegetarian food from the "fringe" to the center of the American dinner plate, Mollie Katzen has been named by Health magazine as one of the five "Women Who Changed the Way We Eat." Her best-known work, "Moosewood Cookbook," was a 2007 inductee into the James Beard Cookbook Hall of Fame and is listed by The New York Times as one of the best-selling cookbooks of all time. Learn more at www.molliekatzen.com.