Researchers believe that HDL works opposite LDL. HDL picks up cholesterol off the walls of the arteries and takes it back to the liver where it can be broken down and removed. This helps to keep the blood vessels open. Cholesterol can be measured by a simple blood test. To reduce the risk of cardiovascular disease, adults should keep their LDL cholesterol below 160 mg/ dL and their HDL cholesterol above 40 mg/dL.

Cholesterol is a necessary and important part of cell membranes. It also is converted into some types of steroid (sex) hormones. Cholesterol comes from two sources. The liver makes all the cholesterol the body needs from other nutrients. However, other animals also make cholesterol. When humans eat animal products, they take in more cholesterol. Cholesterol is found only in foods from animals, never in plant foods. The foods highest in cholesterol are organ meats such as liver, egg yolk (but not egg whites), whole-fat dairy products (butter, ice cream, whole milk), and marbled red meat. To reduce the risk of cardiovascular disease, adults should keep their consumption of cholesterol below 300 mg daily. In 2007, the average American man ate 337 mg of cholesterol daily and the average woman ate 217 mg.

Cholesterol and fats

There are three types of fats in food. Saturated fats are animal fats such as butter, the fats in milk and cream, bacon fat, the fat under the skin of chickens, lard, or the fat a piece of prime rib of beef. These fats are usually solid at room temperature and they are considered “bad” fats because they raise LDL cholesterol.

Unsaturated fats can be monounsaturated or polyunsaturated (This refers to one aspect of their chemical structure.) Monounsaturated fats are “good” fats that help lower cholesterol levels. Olive oil, canola oil, and peanut oil are high in monounsaturated fats. Corn oil, soybean oil, safflower oil, and sunflower oil are high in polyunsaturated fats. Polyunsaturated fats are not bad, they just are not as good as monounsaturated fats. Fish oils that are high in omega-3 fatty acids are polyunsaturated and are very beneficial in preventing heart disease.

Trans fat is made by a manufacturing process that creates hydrogenated or partially hydrogenated vegetable oils. Trans fat acts like saturated fat, raising the level of LDL cholesterol. It is found in some margarines and in many commercially baked and fried foods. Dietary Guidelines for Americans 2005 recommends that no more than 30% of an individual’s daily calories should come from fat, no more than 10% of calories should come from saturated fat, and people should consume as little trans fat as possible.

The low protein diet was developed by dietitians and nutritionists in response to adverse effects that protein can have on persons with kidney or liver disease. Proteins are required for growth, upkeep, and repair of body tissues. They also help the body fight infections and heal wounds. Protein contains 16% nitrogen, which the body eliminates in the urine as urea. In cases where liver or kidney function is impaired, urea, ammonia or other toxic nitrogen metabolites may build up in the blood. The low protein diet is designed to reduce these nitrogen metabolites and ammonia in individuals with liver disease or kidney failure and to reduce the workload on the kidney or liver. If the kidneys, which are responsible for excretion of urea, are not functioning properly (renal failure), or if high levels of protein are continually present in the diet, urea and other toxic nitrogen compounds build up in the bloodstream, causing loss of appetite, nausea, headaches, bad taste in the mouth, and fatigue as well as possibly further adversely affecting the kidney or liver.

The low protein diet focuses on obtaining most of a person’s daily calories from complex carbohydrates rather than from proteins. There are two main sources of protein in the diet: higher levels are found in animal products, including fish, poultry, eggs, meat, and dairy products), while lower levels are found in vegetable products (breads, cereals, rice, pasta, and dried beans). Generally foods in the high protein food group contains about 8 grams of protein per serving. Cereals and grains have about 2 grams of protein in 1/2 cup or 1 slice. Vegetables have about 1 gram of protein in 1/2 cup, while fruits have only a trace amount of protein in 1/2 cup. To control protein intake, foods such as starches, sugars, grains, fruits, vegetables, fats, and oils should be eaten at levels sufficient to meet daily energy needs. If a person has diabetes, the diet must also be designed to control blood sugar.

Protein should never be completely eliminated from the diet. The amount of protein that can be included in the diet depends on the degree of kidney or liver damage and the amount of protein needed for an individual to maintain good health. Laboratory tests are used to determine the amount of protein and protein waste breakdown products in the blood. A suggested acceptable level of protein in a low-protein diet is about 0.6g/kg of body weight per day, or about 40 to 50 grams per day. A person suffering from a kidney disease such as nephrotic syndrome, where large amounts of protein is lost in the urine, should ingest moderate levels of protein (0.8 kg per kg of body weight per day).

A sample menu for one day might include:

Breakfast: 1 orange, 1 egg or egg substitute, 1/2 cup rice or creamed cereal, 1 slice whole wheat bread (toasted), 1/2 tablespoon margarine or butter, 1/2 cup whole milk, hot, non-caloric beverage, 1 tablespoon sugar (optional).

Lunch: 1 ounce sliced turkey breast, 1/2 cup steamed broccoli, 1 slice whole wheat bread, 1/2 tablespoon margarine or butter, 1 apple, 1/2 cup gelatin dessert, 1 cup grape juice, hot, non-caloric beverage, 1 tablespoon sugar (optional).

Mid-Afternoon Snack: 6 squares salt-free soda crackers, 1/2 tablespoon margarine or butter, 1 to 2 tablespoons jelly, 1/2 cup apple juice.

Dinner: 1/2 cup tomato juice, 1 ounce beef, 1 baked potato, 1 teaspoon margarine or butter (optional), 1/2 cup steamed spinach, 1 slice whole wheat bread, 1/3 cup sherbet, 4 apricot halves, hot, non-caloric beverage.

Evening Snack: 1 banana.

This sample menu contains about 1850 calories, with a protein content of 8%.

Special, low protein products, especially breads and pastas, are available from various food manufacturers for persons who need to follow a low protein diet. Specific information on the protein content of foods can be found on food labels. Books that list protein contents of various foods as well as low protein cookbooks are also available.

In addition, it is recommended that fat calories be obtained from monounsaturated and polyunsaturated fats. In order to be effective, some persons may also be required to reduce their sodium and potassium ingestion in foods. Sodium restriction improves the ability to control blood pressure and body fluid build-up as well as to avoid congestive heart failure. Foods with high sodium contents, such as processed, convenience and fast foods, salty snacks, and salty seasonings, should be avoided. Potassium is necessary for nerve and muscle health. Dietary potassium restriction is required if potassium is not excreted and builds to high levels in the blood, which may result in dangerous heart rhythms. At very high levels, potassium can even cause the heart to stop beating.

As kidney function decreases, the kidneys may reduce their production of urine, and the body can become overloaded with fluids. This fluid accumulation can result in swelling of legs, hands and face, high blood pressure, and shortness of breath. To relieve these symptoms, restriction of fluids, including water,soup, juice, milk, popsicles, and gelatin, should be incorporated into the low protein diet. Liver disease may also require dietary fluid restrictions.

Tyrosinemia is a rare but serious inherited disease that may also require the use of a low-protein diet. Tyrosinemia is an inborn error of metabolism in which the body can not effectively break down the amino acid tyrosine.

The federal Dietary Guidelines for Americans 2005 recommends that no more than 30% of an individual’s daily calories come from fat. Beyond that, no more than 10% of calories should come from saturated fat and people should consume as little trans fat as possible. The American Heart Association’s Nutrition Committee joined with the American Cancer Society, the American Academy of Pediatrics, and the National Institutes of Health to endorse these guidelines as part of a healthy diet. However, some experts believe that for heart health the amount of fats consumed should be much lower.

Nathan Pritikin, originator of the Pritikin Diet Plan developed a very low fat diet for heart health. The Pritikin Plan calls for less than 10% of calories to come from fat. The diet is also low in protein and high in whole-grain carbohydrates. Respected independent research shows that this diet does cause weight loss and lower risk factors for heart disease such as cholesterol and blood triglycerides Critics of the diet say that it is too difficult to stay on and that low the fat component of the diet does not allow people to get enough beneficial fats such as omega-3 fatty acids.

The Dr Dean Ornish Diet is another very low fat diet where only aboug15% of calories come from fat. The Ornish diet is an almost-vegetarian diet. It too is designed to promote heart health, and again critics claim hat it does not provide enough essential fatty acids.

Other low fat diets are designed for people who have digestive disorders. People who have gallstones or gallbladder disease often benefit from reducing the amount of fats they eat. Bile, a digestive fluid made in the gallbladder, helps break down fats. When the gallbladder is not functioning well, a low fat diet can improve digestion. Symptoms of other gastrointestinal problems, such as diarrhea, irritable bowel disorder, various malabsorptive disorders, and fatty liver, often improve on a low fat diet. People who have had weight loss surgery usually have fewer digestive problems if they eat a low fat diet.

Managing a low fat diet

People on low fat diets need to avoid certain foods. High-fat foods include whole milk and whole milk products such as ice cream or cream cheese, fried foods, marbled beef, chicken skin, spare ribs or any meat with visible fat, tuna packed in oil, regular salad dressing, potato chips and fried snack foods, and many baked goods—cookies, cakes, pies, and doughnuts.

People wishing to reduce the fat in their diet must read food labels. Food labels are required to list in the nutrition information panel nutrition facts that include calories, calories from fat, total fat, saturated fat, trans fat, cholesterol, sodium, total carbohydrates, dietary fiber, sugars, protein, vitamin A, vitamin C, calcium, and iron In addition, the following words have specific legal meanings on food labels.

• Fat-free: less than 0.5 grams of fat per serving.
• Low fat: no more than 3 grams or less of fat per serving.
• Less fat: A minimum of 25% less fat than the comparison food.
• Light (fat) A minimum of 50% less fat than the comparison food.

The home cook can also reduce fat in the diet in the following ways:

• Remove all visible fat from meat and skin from poultry before cooking.
• Bake or broil meats on a rack set in a pan, so that the fat can drip off.
• Refrigerate homemade soups and stews, then skim the solidified fat off the top before serving.
• If using canned soup or broth that contains fat, put the can in the refrigerator for a few hours, and skim the solid fat off the top before heating.
• • Use low-fat yogurt and herbs on baked potatoes in place of butter or sour cream.
  • Top pasta with vegetables instead of oil, butter, or cheese.

  To reduce fat in meals when eating out:

  • Choose items that are broiled, roasted or baked. Avoid fried foods.
  • Select fish or chicken instead of beef or pork.
  • Ask for salad dressing, butter, and gravy on the side.
  • Fill up on salad with non-fat dressing at the salad bar.