Читать книгу 16 Myths of a Diabetic Diet - Karen Hanson Chalmers - Страница 11
ОглавлениеPeople with diabetes should follow a high-protein diet to stay healthy and strong.
MARK: I’ve been reading that I should probably be on a high-protein, low-carbohydrate diet to help keep my blood sugars down.
DIETITIAN: While it is important to get enough protein in our diets to stay healthy, most of us get more than we need. We still need to get most of our calories from carbohydrate rather than protein, even if you have diabetes, because our bodies use carbohydrate for energy.
MARK: Okay, but because I’m exercising more to lose weight, plus lifting weights, shouldn’t I be eating a lot of protein or even taking protein supplements to build more muscle?
DIETITIAN: Actually, the only way to really build stronger muscles is with regular exercise and a meal plan that contains anywhere from 40 to 60% of calories from carbohydrate, not from taking protein supplements or eating large portions of protein. Too much protein may even be harmful to your kidneys, especially if your doctor told you that you are spilling some protein in your urine.
WHAT’S NEXT?
Like Mark, most people think they don’t get enough protein in their diets. There have been so many misconceptions over the years about protein and what it can do for us that we sometimes wonder if we truly get enough. Protein has practically been touted as a miracle nutrient. Several popular diets claim that eating more protein and less carbohydrate can help you melt away the pounds.
Many people with diabetes often end up eating more protein and less carbohydrate in an effort to control blood glucose levels. If you’re looking to “bulk up,” you may have tried protein powders that are often sold in health food stores (after all, muscles are made of protein, so it makes sense to eat more protein to build bigger muscles, right?). Yet, most of us eat too much protein, often at the expense of other nutrients, which can potentially lead to some serious health problems. Let’s take a look at the truth behind some of these misconceptions about protein.
THE OLD AND THE NEW
The history of the role of protein in the diets of people with diabetes has been long and ever changing. Before the discovery of insulin, the only course of treatment involved dietary measures. Because people with diabetes were extremely limited in the amount of carbohydrate they could eat, the prescribed diets were usually high in protein and/or fat and often involved eating very strange foods, such as suet, blood, and even 10–40 egg yolks every day! Bread, pasta, and even fruit were off limits.
In the early 1900s, Dr. Elliot Joslin recommend limiting protein intake to 1 gram per kilogram of body weight because too much protein in the diet was found to increase both nitrogen and glucose in the urine, further aggravating diabetes. Have you ever been told that approximately 50–60% of the protein that you eat gets converted into blood sugar? This information came about in the 1930s using eggs, casein, and meat as the basis for studies of how protein affects metabolism in people with diabetes. Some health care professionals still use this information today, although more recent studies have challenged whether this “fact” is indeed true.
Much has changed over the years regarding the best diet for someone with diabetes. Because there are only three main nutrients to work with, diets have ranged from high fat to high protein to high carbohydrate. Even today, with some of the most advanced treatments for diabetes ever, leading health and diabetes authorities still can’t agree upon the best diet for people with diabetes. Some believe a higher-protein diet is best, whereas others argue that a high-carbohydrate diet is the way to go, because a higher-protein diet could lead to some possible health problems down the road. Who is right? Although we may not have a definitive answer right now, read on to learn more about this controversial nutrient.
WHAT IS PROTEIN?
The word “protein” comes from the Greek word proteios, which means “of the first rank.” No wonder we give it such importance in our diets! A protein is an organic substance made up of carbon, hydrogen, and oxygen (just like carbohydrate), but unlike carbohydrate, protein also contains nitrogen. These atoms are arranged into amino acids, which are linked into chains to form protein molecules. Amino acids are the building blocks of proteins, and there are 22 amino acids that are linked together in various combinations to form different types of protein molecules. Nine of these amino acids are called “essential” because our bodies cannot make them; they must be obtained from foods that we eat. It is important that we eat foods that contain essential amino acids because our cells need all 22 amino acids to make body proteins.
WHY DO WE NEED PROTEIN?
Protein has many important functions in the body. These include:
• creating new cells when old ones die
• forming antibodies (which fight viruses and bacteria)
• creating visual pigment to help us see
• forming enzymes (for example, digestive enzymes)
• forming certain hormones (such as insulin)
All of the cells in our bodies contain protein. In fact, approximately 50% of the body’s weight comes from protein. Our hair, nails, muscle, cartilage, bone, and body fluids contain many different kinds of protein.
When we eat foods that contain protein, the protein is broken down into its building blocks, the amino acids. Our bodies then decide how those amino acids will be used and arrange the amino acids in a specific order, based on what types of proteins are needed. For example, the protein needed to help blood to clot (called thrombin) will have a different sequence of amino acids than the kind of protein needed to make insulin. Whatever amino acids are left over from protein synthesis will be stored as…you guessed right, fat.
Most people in the U.S. grow up believing that a meal isn’t a meal unless it contains a source of protein, usually in the form of a piece of steak, a hamburger, or a chicken breast. After all, who could stay healthy just by eating a plate of spaghetti? Surprisingly, although we do need to eat protein every day, we need much less than you may think. On average, people in the U.S. get approximately 15% of their calories from protein, which translates into 1.5 grams of protein per kilogram body weight. This is twice what is needed to meet our daily requirements, whether we have diabetes or not. Only about three percent of Americans have a protein intake that is below the recommended amount.
The recommended dietary allowance (RDA) for protein is 0.8 grams per kilogram body weight for adults. (We actually need only 0.6 grams of protein per kilogram body weight to stay healthy, but a margin of safety is built into the RDA). To give you an example, a man who weighs 170 pounds (77 kg) needs 62 grams of protein in his diet every day. A woman who weighs 130 pounds (59 kg) only needs 47 grams per day. Infants, children, and adolescents require more protein for growth and development; therefore the RDAs are higher (0.9–2.2 grams per kilogram of body weight per day). Protein needs are increased during pregnancy and lactation as well.
Diabetes and Protein Requirements
You’ve learned that there is no longer a set diabetic diet for people with diabetes. The best “diet” is one that will help you best control your diabetes and stay healthy. Also, recommendations for various nutrients can vary, depending on the type of diabetes you have and how well you are able to manage your diabetes. The American Diabetes Association states that there’s no good evidence that aiming for a protein intake between 15 and 20% of calories should be modified.
More recently, however, some studies are showing that people with type 2 diabetes may actually benefit from a slightly higher protein intake. The theory that approximately 50–60% of protein in the diet gets converted to blood glucose (dating back to the early part of this century) has been challenged. A few studies have shown that blood glucose levels do not rise in people with type 2 diabetes who eat a diet containing a moderate amount of protein. Perhaps not as much protein is metabolized into glucose as we once thought. A similar effect has been seen in people with type 1 diabetes, although large amounts of protein do require more insulin to prevent high blood glucose levels (insulin is needed to help the body use protein, fat, and carbohydrate). Other studies have shown that a slightly higher intake of protein may lead to more weight loss compared with a more traditional, lower-fat eating plan and can even lower your risk for heart disease. Furthermore, eating a little more protein can help curb your appetite while preserving lean body mass if you’re trying to lose weight. For these very reasons, the Joslin Diabetes Center nutrition guideline for people with type 2 diabetes recommends that between 20 and 30% of calories come from protein.
Does this mean that if you have type 2 diabetes you can eat more protein in your diet without it affecting your diabetes control? The answer varies from person to person. The best way for you to determine how protein affects your blood glucose control, whether for a meal or a snack, is to be diligent about checking your blood glucose levels after eating. It’s also important not to eat too much protein because extra protein means extra calories. There is also the risk of too much protein worsening diabetic kidney disease and leading to other health problems, such as osteoporosis, kidney stones, and possibly certain types of cancer. It’s important to talk with your dietitian about how much protein you need to stay healthy.
WHERE IS PROTEIN FOUND?
Once you know how much protein you need every day, you then need to learn what foods contain protein. However, you most likely know this already! Chances are, you are picturing steak, pork chops, turkey, and fish. Animal sources of protein include:
• red meats (beef, pork lamb, veal
• poultry (chicken, turkey, duck, goose)
• seafood (fish, shellfish)
• 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 older cousins. The underlying premise for most of these books is that a low-fat, high-carbohydrate diet can actually make you fat because carbohydrates cause the body to release insulin, which, in turn, leads to fat storage. What many readers who are desperate for the quick, easy solution to permanent weight loss do not realize is that there are no good studies showing that insulin causes weight gain (a common theme found in many of these books). Unfortunately, they may be led to believe that these lower-carbohydrate, higher-protein diets are the answer to their weight-loss woes, particularly when they actually do lose weight.
How can we explain the weight loss that does result from these diets? Well, what they have in common is that they all manage to cut calories, some more drastically than others. There really is no special magic here. Whenever you decrease your caloric intake, weight loss will result. Keep in mind, too, that some of these diets have much more fat, especially saturated fat, than we should be consuming, which may spell trouble for your arteries down the road. Plus, if you follow the advice of some of these diets, you’ll find yourself following strict rules as to when you can eat, what you can eat, and what combinations of foods you can eat. Once again, there is no solid evidence backing up these claims. As we mentioned earlier, a slightly higher protein intake may help people lose weight—along the lines of 30% of calories from protein and no less than 130 grams of carbohydrate per day. But ultra-low carbohydrate plans are not realistic, or healthy, to follow for long periods of time.
