There?s always a new diet in vogue—whether it?s the low-fat diet, the high-protein diet or the low-carb diet. And with each new dieting craze, we get clamorous proclamations like ?all carbs are bad,? or ?all fat is bad.?
But before you—or your customers—rush to conclusions about these dietary claims, it helps to know exactly what a carb, a protein or a fat is. With a little nutritional background, you?ll be able to help your customers understand the science behind the dietary hype.
Protein has been making a lot of news lately, and for good reason. Protein, found in cells of hair, tissue, bone and muscles, makes up a substantial portion of our bodies. Proteins, in turn, are made up of amino acids—organic molecules that combine to form living organisms.
Protein is vital to basic bodily functions. Proteins that are biologically active in our bodies include enzymes, hemoglobins, immunoglobulins, hormones and neurotransmitters, among others. These proteins help to keep the heart beating and the blood flowing, and they bind the essential minerals the body requires for good health.
But not all proteins are created equally. Animal proteins, including meat and seafood, typically contain all of the essential amino acids the body needs, so they are called complete proteins. However, proteins derived from fruits, vegetables, grains and nuts don?t typically contain all the necessary amino acids and are therefore known as incomplete proteins.
?One source of nonanimal protein that?s complete is soy,? says Tara Geise, a registered dietitian and spokeswoman for the American Dietetic Association. ?For vegetarians who don?t enjoy soy, just eat a variety of foods. For instance, beans have certain amino acids that rice doesn?t and vice versa, so if you eat both beans and rice you?ll get a more complete combination of amino acids. Legumes in general are another great vegetarian protein source. And for vegetarians who don?t exclude dairy and eggs, both of those are also complete protein sources.?
Get to know your carbs
It?s hard to walk down the aisles of a grocery store these days without seeing signs that trumpet ?Low Carb!? But despite the current focus on limiting foods with carbohydrates, they are in fact another essential building block of the human diet, and necessary for maintaining good health. Carbs come from a wide variety of sources including breads, grains, cereals, dairy and fruits. A carbohydrate is made up of sugar molecules. Roughly, carbs can be broken down into three categories: starches, fiber and sugar. The body converts most carbohydrates into glucose, an essential energy source that fuels the brain, kidney, muscles and other tissues. Fiber, however, can?t be broken down into sugar molecules, and so passes through the body undigested, making it an excellent natural cleanser.
Carbohydrates have traditionally been classified as either ?simple? or ?complex.? The distinction is not terribly technical?simple carbohydrates consist of foods that have only one sugar, whereas complex carbohydrates are made up of foods that contain three or more linked sugars.
More recently, nutritionists have begun classifying carbohydrates according to where they fall on the glycemic index. ?The glycemic index is supposed to tell us how the body utilizes carbohydrates, and what effect carbohydrates have on blood sugar levels,? says Cindy Moore, another registered dietitian with the ADA. ?The index compares various foods with the impact of a predetermined amount of sugar. So when you see a certain number, it?s a reflection of how your body responds to that food, compared to how it would have responded to sugar.? Carbohydrates that break down quickly, and hit the bloodstream faster, like a white baguette, have the highest glycemic index numbers. Those that break down slowly, and therefore release the glucose more gradually, like barley, have a lower glycemic index number.
To complicate matters, certain diet proponents, as well as food and supplements manufacturers, have started using the term net impact carbs (or sometimes, just net carbs.) Net carbs are calculated by subtracting the fiber and sugar alcohols from the total carbohydrates. The claim is that because the body doesn?t digest fiber, it shouldn?t be counted among carbs, and the sugar alcohols have a minimal effect on blood sugar and therefore also shouldn?t be counted.
?Unlike terms such as fat free, low fat and reduced fat, these descriptions of net carb levels are meaningless at this point because the Food and Drug Administration has not set guidelines defining them,? says Susie Nanney, manager of the Obesity Prevention Center at the School of Public Health at Saint Louis University. ?Until they?re regulated, consumers should know that the only way to be sure these products are significantly different is to compare their carb counts with those of traditional products. To do that, look at the ?total carb? numbers on the nutrition labels on the back of food packages.?
Good fat, bad fat
The message in dietary circles used to be simple to digest: Fat was bad. But the message about fat turns out not to be so simple after all. As far as health is concerned, some fats are bad for you while other fats are actually very beneficial.
The fats that are considered ?bad??trans fatty acids and saturated fats—are those that increase the body?s bad cholesterol levels. Trans fats are produced by adding hydrogen to vegetable oils, a process known as hydrogenation. Trans fats not only raise bad cholesterol (LDL), but also deplete good cholesterol (HDL). Unfortunately, because hydrogenated oils have a long shelf life, they are frequently found in processed and commercial foods, such as margarine, snack foods and fried foods.
Saturated fats are mostly derived from animal fats, such as butter, cheese, whole milk and meat. They are also found in a few plant-based sources, such as coconut and palm oils. The bad thing about saturated fats is that they raise your bad cholesterol (LDL), although they also raise your good cholesterol (HDL).
The good fats are those that can improve your blood-cholesterol levels—the polyunsaturated and monounsaturated fats. Monounsaturated fats are derived mainly from olive, peanut and canola oils, as well as from avocados, while polyunsaturated fats are found in corn, soybean, safflower and sunflower seed oils, as well as fish. ?Fat matters,? Nanney asserts. ?The issue[s] of concern [are] both types of fat and total amount consumed. Both polyunsaturated and monounsaturated fats can result in less LDL and more HDL cholesterol production in the body. You need some fat in the food you eat, but choose sensibly.?
Your body needs all three essential building blocks of nutrition—protein, carbohydrates and good fats—to remain healthy. Finding the ideal balance of these nutritional elements for any given individual is a matter of experiment and observation. As with all aspects of nutrition, ?moderation in all things? is an invaluable rule of thumb.
Lynn Ginsburg is co-author of What Are You Hungry For? Women, Food and Spirituality (St. Martin?s Press, 2002).
Natural Foods Merchandiser volume XXV/number 7/p. 14, 20