HELP ON DIABETES

The Three Components of a Meal

All foods are composed of three components—carbohydrates, fats, and proteins (also called macronutrients)—in varying amounts and quality.

CARBOHYDRATES (CHO)

Starchy foods such as rice, pasta, potatoes, breads, and beans and sugary foods like fruits and milk are rich in carbohydrates (CHO). A focus on carbohydrates is nec­essary because the blood glucose rise after a meal is mostly due to the digestion and absorption of the carbohydrates in the meal. If you have type 1 diabetes, your insu­lin dosage for a meal is calculated according to the amount of carbohydrate in your meal.

If you have type 2 diabetes, you will need to have some carbohydrate restriction to avoid excessive increases in glucose levels after a meal, even if your diabetes is controlled with diet or oral medications.

The Glycemic Index

Different carbohydrates behave differently in the body: they vary in how much they raise the blood glucose level after ingestion. The glycemic index is the ranking given to carbohydrate-containing foods according to how much they raise blood glucose levels when compared to drinking 50 grams of glucose. For example, the rise in glucose levels after eating white bread is very similar to the rise after drink­ing glucose, so it has a glycemic index of 100 percent. In contrast, an apple has a glycemic index of 38, meaning that it will raise the glucose level much less.

The glycemic index depends on

• The fiber content of a food—the higher the fiber content, the lower the glycemic index.

• How much the food has been processed—so mashed potatoes have a higher glycemic index than baked potatoes, which are less processed. Similarly, al dente pasta has a lower glycemic index than overcooked pasta.

• The fat content of a food—fat delays stomach emptying and slows glucose absorption. Thus full-fat milk has a low glycemic index (27 percent).

When choosing what carbohydrates to eat, you cannot just focus on the glycemic index of each food, because the glycemic index of a food is affected by how much it has been processed and cooked, as well as the fat content of the meal. Instead, you want to eat fewer processed foods and more foods with high fi ber, because these foods have a relatively low glycemic index.

Fiber

Fibers are starches that are resistant to digestion (although approximately 10 per­cent of them are digested by bowel bacteria and absorbed). Soluble (or gel forming) fibers are found in apples and other fruits, and insoluble fibers are found in cereals and vegetables. For a person who has diabetes, foods with a high fiber content are beneficial because the fiber slows down glucose absorption and prevents high glu­cose levels after meals. There are two drugs, acarbose (Precose) and miglitol (Gly­set), used in the treatment of type 2 diabetes that act by delaying the absorption of glucose from the bowel, so in a sense they act similarly to a high-fiber diet.

Generally speaking, in a normal diet, about 50 percent of the daily caloric intake is in the form of carbohydrates. However, in many individuals with type 2 diabetes who also have high triglycerides and low HDL cholesterol, this degree of carbohy­drate intake may be too much. In these cases, it would be beneficial to reduce the overall amount of carbohydrate, yet eat foods with high fiber content.

Eating too many carbohydrates does not cause diabetes. Experiments have shown that elevated free fatty acids levels can damage beta cells. So it is possible that in a susceptible person, a high-carbohydrate diet can increase the free fatty acids to a level that can injure the islets and impair insulin secretion, but this is only a hypoth­esis.

Artificial Sweeteners

Used in moderation, table sugar (sucrose) can be a part of your diet. However, if you are having problems with glucose control or you are trying to limit your carbohy­drate intake (for weight loss or lowering triglycerides), reducing the amount of sugar you eat may be important to you. If this is the case, you have the option of using sweeteners that do not raise blood glucose levels. Aspartame (NutraSweet) consists of two major amino acids, aspartic acid and phenylalanine, which combine to pro­duce a sweetener 180 times as sweet as sucrose. A major limitation is that it is not heat stable, and so it cannot be used in cooking. Saccharin (Sweet ’N Low), sucra­lose (Splenda), and acesulfame potassium (Sweet One) are other sweeteners that can be used in cooking and baking.

Fructose is a natural sugar substance that is a highly effective sweetener and only slightly increases blood glucose levels, and it does not require insulin for its metabo­lism. However, high amounts of fructose do raise triglycerides and cholesterol, so it is not really that advantageous as a sweetening agent. Of course, you can still eat fructose-containing fruits and vegetables or fructose-sweetened foods in moderation.

Sugar Alcohols

Sugar alcohols, also know as polyols or polyalcohol, are commonly used as sweet­eners and bulking agents. They occur naturally in a variety of fruits and vegetables, but are also commercially made from sucrose, glucose, and starch. Examples are sorbitol, xylitol, mannitol, lactitol, isomalt, maltitol, and hydrogenated starch hydro­lysates (HSH). If the food has just one sugar alcohol it will be listed separately on the food label, but if the food contains several sugar alcohols the label will just say “sugar alcohols.” They are not as easily absorbed as sugar and so do not raise blood glucose levels as much. Therefore, they are often present in food products that are labeled “sugar free” such as chewing gum, lozenges, hard candy, and sugar-free ice cream. If you consume enough of these foods, however, they will raise the blood glucose, and so you need to count half the carbohydrate listed on the food label that comes from sugar alcohol. If you consume too much of these sugar alcohols, you may experience side effects such as bloating and diarrhea. If you are counting calo­ries, remember that sugar alcohols have lower caloric content than sugar (1.5 to 3 kcals per gram as opposed to 4 kcals per gram of sugar).

FATS

Fat is necessary in moderation and important for good health. It is an important source of calories and should contribute 25 to 35 percent of daily energy require­ments. Fats are necessary for the absorption of vitamins A, D, E, and K. Fat also tastes good and makes us feel full.

Understanding the fat content of a meal is important for a number of reasons. First of all, fats are the most energy-dense foods. One gram of fat contains 9 kcals, whereas a gram of proteins and carbohydrates contains 4 kcals. Therefore, fat restriction is an important part of any weight-reducing diet. Second, different kinds of fats can also affect the lipid profile and so may have an effect on development of heart disease.

Not all fats are the same—there are three types of fats:

•Saturated fats are found in animal fats such as lard, butter, cheese, milk, and meat and in coconut and palm kernel oil.

•Monounsaturated fats are found in olive oil, canola oil, and peanuts and other nuts.

•Polyunsaturated fats are found in vegetable oils such as saffl ower, corn, soybean, and sunflower oil and also in fish and seafood.

A lot of foods contain a combination of these different types of fats: for example, avocados contain all three types.

Saturated fats increase LDL cholesterol, but they also increase HDL cholesterol, and so the effect of saturated fats on increasing the risk of heart disease is probably modest. What has been shown in scientific studies is that when you replace satu­rated fats with monounsaturated and polyunsaturated fats, you lower your total cho­lesterol levels and risk of heart disease.

Trans-Fatty Acids (Trans Fats)

Trans fats are harmful because they increase the risk of heart disease. They are produced when vegetable oils are converted into semisolid fats such as margarine and vegetable shortening. They are also known as partially hydrogenated vegeta­ble oils. There are some naturally produced trans fats in dairy products, but most of the trans fats in our diet are man-made. Manufacturers put them in food products to increase the product shelf life—for example, crackers stay crispy longer. The prob­lem is that they appear to raise LDL cholesterol (the “bad” cholesterol) and lower the HDL cholesterol (the “good” cholesterol). They may also have a negative effect on the cells lining the blood vessels, promoting atherosclerosis.

Omega-3 Fatty Acids

Omega-3 fatty acids are a kind of polyunsaturated fat that lowers the triglycerides and raises HDL cholesterol. There are three important omega-3 fatty acids for human nutrition:

• Alpha-linolenic acid

• Eicosapentaenoic acid

• Docosahexaenoic acid

Humans cannot synthesize omega-3 fatty acids—they must be obtained from the diet. Good dietary sources include

•          Oily cold-water fish such as salmon, herring, mackerel, anchovies, and sardines

•          Flaxseed oil (about 55 percent ALA), canola oil, walnut oil, soybeans, and pumpkin seeds

You may have to consume up to 3 grams of omega-3 fatty acids daily to lower your triglyceride levels. Doses higher than this may be harmful—they may increase the risk of a hemorrhagic stroke (bleeding into the brain).

Getting 1 gram of omega-3 fatty acids from fish would mean eating two or three six-ounce servings per week. There has been some concern that fish may have accu­mulated heavy metals such as mercury and pollutants such as PCBs and dioxin.

Fortunately, you can buy a pure distilled form of omega-3 fatty acids as capsules, which can be taken as a dietary supplement. There is also a prescription product called Lovaza that your doctor can prescribe.

Cholesterol

Cholesterol is not a fat—it is a chemical that has a number of important functions:

•It is a building block for a number of important hormones, including the sex hormones testosterone and estrogen.

•It is part of the insulation around nerves.

•It is a component of the membranes surrounding all the cells in the body.

•It is the precursor for bile acids, which are important for fat absorption.

The reason that we often discuss cholesterol when talking about fats is that in the bloodstream, the particles that transport fats (as triglycerides) also transport choles­terol, and these particles (LDL, VLDL, HDL, chylomicrons) are involved in the processes that cause heart disease. A reduction in total fat consumption reduces cholesterol levels by 10 to 15 percent. The cholesterol in the diet should be less than 300 mg per day. If your LDL cholesterol level is more than 100 mg/dl, the amount of cholesterol in your diet should be less than 200 mg per day.

PROTEINS

Protein intake for a person with diabetes should be the same as in a person who does not have diabetes. In the United States, protein accounts for about 15 to 35 percent of the total energy consumed per day, and there is no reason that people with diabetes should have a different amount. The only exception is in people with diabetic kidney disease. Too much protein can worsen the kidney disease, and so they need to restrict their protein intake to less than 0.36 grams per pound per day. For example, for a person weighing 154 pounds, 154 pounds 0.36 55 grams of protein per day.