• dairy foods (milk, yogurt, cheese, eggs)
These animal protein foods contain all of the essential amino acids; therefore, they are often called “complete” protein foods. These foods provide adequate protein to meet the body’s protein needs. It is relatively easy for both men and women to meet their daily protein requirements by eating fairly small amounts of protein.
Let’s first calculate how much protein a 130-pound woman requires each day:
130 lbs ÷ 2.2 = 59 kilograms (kg)
59 kg × 0.8 g/kg = 47 g protein per day
We can then figure out how she can meet this daily requirement by eating animal sources of protein:
As you can see, this woman’s daily protein needs can easily be met by eating just these three sources of animal protein. It is no more challenging for men to meet their protein needs, even though they need more than women, because men tend to eat more than women, anyway.
The main problem with animal protein is that you get more than you bargain for. Animal sources of protein are often high in fat, mainly saturated fat. Saturated fat, in turn, is responsible for raising cholesterol levels, which can lead to heart disease. Because the majority of our protein intake comes from animal sources, it’s really no surprise that our fat intake has also increased. Some of these animal foods contain more calories from fat than from protein. It’s important to make sure you choose the leanest forms of animal protein foods to avoid the dangers of excess fat in your diet, which include obesity, heart disease, and cancer.
Protein from Plants?
Believe it or not, plants also contain protein, in addition to carbohydrate. In fact, someone who is a vegetarian probably gets most of his or her protein from plant foods. You may be curious (or even somewhat skeptical) about these plant proteins—just where are they found? A primary source of plant protein is from the legumes, or dried beans and peas. Examples are:
• kidney beans
• chickpeas (garbanzo beans)
• black beans
• soy beans
• lentils
• split peas
One-half cup of beans or peas contains 8 grams of protein, which is the amount of protein found in 1 ounce of meat, poultry, or fish. Keep in mind that this same serving of beans or peas also contains about 15 grams of carbohydrate.
Other sources of plant proteins are soy foods (tofu, soymilk, soy cheese, etc.), nuts, seeds, and “meat analogs,” which are vegetarian-style (meatless) versions of typical meat foods, such as burgers, hot dogs, and sausage. Meat analogs are made from soybeans, vegetables, and/or grains, such as oatmeal. Remember that these foods eaten alone will not supply you with all of those essential amino acids we mentioned earlier. But you can get the amino acids by combining them with other foods. Are you turning up your nose at this point? Well, here are some very common foods that you probably already eat that are “complete” protein foods:
• peanut butter and jelly sandwiches
• black beans and rice
• vegetarian chili
• refried beans and tortilla chips
• minestrone soup
• hummus (chickpea spread) and pita bread
The beans or nuts and the grain foods (bread, rice, pasta, or tortillas) complement each other. When they are paired up, they provide you with protein just like that found in meat.
Why would you want to eat plant protein foods instead of animal protein foods? Well, for several reasons. First, plant-based meals tend to be healthier for you. You already know that many animal protein foods are high in both total fat and saturated fat. Plant protein foods are lower in fat, low in saturated fat, and contain more fiber. Second, plant-based meals add variety to your weekly menus. Third, meatless meals can be easy on your budget. Plant protein foods are much less expensive than meat, poultry, or fish.
THE UPSIDE AND THE DOWNSIDE OF PROTEIN
The Role of Protein in Diabetes and Kidney Disease
Diabetic kidney disease, called nephropathy, is one of the major complications of diabetes. The kidneys act like filters in the body, working to remove toxic substances. The substances that are removed are excreted in the urine. Uncontrolled diabetes can lead to damage of the small filtering units of the kidney called glomeruli. Normally, glomeruli work to keep certain particles, such as protein, from being expelled in the urine. If these glomeruli are damaged, which can sometimes happen with diabetes, protein molecules can slip through and enter the urine. A small amount of protein in the urine, called microalbuminuria, is an early sign of kidney damage.
We know how important protein is for staying healthy. But for people with kidney disease, sometimes eating large amounts of protein is too much of a good thing. In fact, a high-protein diet can be downright harmful. Although there are still some conflicting opinions about the role of protein in kidney disease, there are good studies showing that a lower-protein diet may actually prevent kidney disease from worsening. People with end-stage renal failure often feel much better if they follow a lower-protein diet because fewer nitrogenous wastes (wastes created when the body processes protein) build up in their blood.
Many physicians and dietitians recommend that people with diabetes who have early nephropathy start to cut back on their protein intake. Does this mean you should stop eating protein? Of course not. A lower-protein diet must be carefully planned, preferably by a dietitian, to make sure you don’t eat too little protein. A lower-protein diet does mean, however, that you need to eat smaller portions of meat, poultry, and fish, as well as limit the amount of dairy foods, such as milk, cheese, yogurt, and eggs, that you eat. There is some evidence that eating more vegetable protein foods may be less harmful to the kidneys than eating animal protein foods. If you are following a lower-protein diet already and would like to try more plant-based meals, speak with your dietitian.
Too Little Protein?
So far, you’ve learned that people tend to eat too much protein and that too much protein may not be so healthy, especially for people with diabetes and kidney problems. What about not eating enough protein? Is this possible in a country known for thick steaks, fried chicken, and clambakes? Unfortunately, protein malnutrition is common in some Third World countries that are unable to adequately feed their citizens. However, the U.S. also has groups of people at risk for protein malnutrition, including low-income families, pregnant women who do not eat enough, alcoholics, and, at higher risk, older adults. Data from the National Health and Nutrition Examination Survey indicates that up to 25% of older Americans do not consume the RDA for protein. In fact, these people may be eating only half of the protein that they need.
An elderly person who lives on a diet of “tea and toast” may lose lean body mass, which is mostly muscle. This, in turn, can lead to loss of strength and decreased muscle contraction, putting that person at risk for falls and injury. Insufficient protein intake can also impair the immune system, making that person more susceptible to disease and lengthening the recovery time from an illness or surgery. Obviously, older people need to make sure they eat a variety of foods, including poultry, fish, lean meats, dairy products, and/or legumes to make sure that they get enough of this important nutrient.
Weight Loss and High-Protein Diets
High-protein, low-carbohydrate diets have been around for several decades. Remember Dr. Atkin’s Diet Revolution? The Stillman Diet? The Scarsdale Diet? The Beverly Hills
Diet? In recent years a fresh batch of new diets—The Zone, Dr. Atkin’s New Diet Revolution, and The South Beach Diet—have appeared, many of which tout the same claims as their