The best protein sources

Do you give your meals more nutritional points if they contain lots of protein? The popularity of protein-rich options has soared recently as high-protein, low-carb diets have become trendy. Protein shakes and bars aren't just for bodybuilders now -- they're being sold as energizing snacks for women on the go. So what's the scoop on this nutrient? Here are the basics of the protein puzzle.

Protein is a nutrient that plays a role in maintaining and repairing cells throughout the body, from our muscles to our immune system. Proteins are made up of compounds called amino acids (amino acids are to proteins what bricks are to a wall). Although the body contains more than 20 amino acids, only nine are considered essential -- they can't be synthesized by the body and, therefore, must come from what we eat.

Sources of essential amino acids
Foods rich in protein containing all these essential amino acids were traditionally thought of as “complete protein foods” because it was assumed you had to get all essential amino acids at each meal. Some of the best-known examples are from animal sources, such as meat, poultry, fish, eggs, cheese, yogurt and milk, although soybeans offer complete proteins, too.

Most proteins of plant origin lack or are low in one or more of the essential amino acids, leading to the earlier thinking (especially by meat eaters) that they don't count as protein sources. But research has shown that choices such as dried beans, lentils and peas, along with nuts, seeds and whole grains, complement one another to provide complete proteins when eaten in the context of a healthy and varied diet.

Healthy doses of protein
Protein-rich foods can be an ally or enemy of the battle of the bulge -- it really depends on the source and how much of it you eat. Some protein-packed foods are linked to a number of lifestyle-related diseases; for example, a large, thick slab of well-marbled steak not only packs a caloric wallop but also plenty in the way of saturated fat and cholesterol, which, if eaten in large doses over a period of time, puts you at risk for heart disease, high blood pressure and kidney failure. Slash fat counts by removing skin from poultry, trimming fat from meat and opting for lower-fat dairy products, or choose high-protein plant foods.

Lean portion-controlled, protein-packed foods can also help stabilize blood-sugar levels, giving you better appetite control and steadier energy levels, particularly when eaten in small amounts earlier in the day. Have an egg, a few ounces of lower-fat cheese, meat, poultry or fish at breakfast and lunch, along with whole grains and fruit or vegetables, and you may banish your ravenous appetites and energy dips mid-morning and mid-afternoon. One of the reasons people have success with high-protein diets is because of the added protein, not because they're cutting carbs.

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Why you should include protein in your diet
A study of overweight women at Saint Louis University in Missouri looked at hunger and the calories consumed following either an egg-based or bagel-based breakfast, both of which contained about the same number of calories. When eggs were on the menu, the women consumed an average of 163 fewer calories for lunch and about 418 fewer calories in 24 hours than those who ate the bagel breakfast.

Another lesser-known perk of protein is that small amounts can boost your metabolic rate, which is your calorie-burning capacity. This phenomenon, called thermogenesis (essentially heating the body), also contributes to that energetic boost you get from exercise.

North Americans seem to have the timing of their protein preferences reversed in comparison to other cultures; for example, in Asian cuisines, much less animal protein is consumed on the whole, and Asians eat their protein earlier in the day, whereas North Americans love their protein-laden evening meals.

Time your protein intake appropriately
Time eating protein with a workout and you'll reap the rewards. Having a protein-packed snack right after a workout has been shown to help build muscle mass -- a definite plus if you're doing weight training.

But going overboard by choosing a high-protein diet can take a toll on more than just your arteries. Excess animal protein can cause calcium loss from bones and contribute to bone thinning. And for those whose kidney function may be compromised -- as it can be for people with diabetes -- too much animal protein can hasten a decline in kidney function.

Plant proteins, on the other hand, can offer a range of disease-fighting compounds. Soy foods, with their healthy fats and phytoestrogens (plant compounds with estrogen-like action), and legumes, which are chock-full of blood-cholesterol-lowering fibre, supply numerous health perks.

Where's the protein

FOOD	AMOUNT	PROTEIN
Beef, lean sirloin, cooked	100 g/3-1/2 oz	31
Chicken breast, no skin, roasted	100 g/3-1/2 oz	31
Wild Atlantic salmon, cooked	100 g/3-1/2 oz	25
Kidney beans, cooked	250 mL/1 cup	15
Milk (2%)	250 mL/1 cup	10
Tofu, extra firm	100 g/3-1/2 oz	7
Cheese, part-skim mozzarella	30 g/1 oz	7
Egg, large	1	6
Brown rice, cooked	250 mL/1 cup	5
Peanut butter	15 mL/1 tbsp	4
Whole wheat bread	1 slice	4
Broccoli	125 mL/1/2 cup	2
*Grams

Rosie Schwartz, RD, is a Toronto-based consulting dietitian.

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This article was first printed in the June 2007 issue of Homemakers Magazine. Click to subscribe online and don't miss an issue.