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Diet and your liver.

What does nutrition have to do with your liver?

Nutrition and the liver are interrelated in many ways. Some are well understood; others are not. But because everything we eat, breathe and absorb through our skin must pass through the liver, special attention to nutrition and diet can help keep the liver healthy. In a number of different kinds of liver disease, nutrition takes on considerably more importance.

Why is the liver important?

The liver is the largest organ in the body and it plays a vital role in regulating life processes. It is responsible for performing many functions which are essential for life. While there are still many things we do not understand about the liver, we do know one thing: it is impossible to live without the liver, and the condition of the liver is a major factor in the quality of one's life.

Among the primary functions of the liver are:

* To convert the food we eat into stored energy, and to regulate the release of that energy when it is needed.

* To act as a filter to remove alcohol and toxic substances from the blood and convert them to substances that can be excreted by the body.

* To receive and modify drugs and medications taken into the body, enabling the body to use them effectively and ultimately dispose of them.

* To serve as a factory for important body chemicals. One of these is bile, a greenish-yellow substance essential for the digestion of fats in the small intestine.

Why is the liver so important in nutrition?

Everything that is absorbed from the stomach and small intestine during digestion passes through the liver before it reaches any other part of the body. This is accomplished through the portal system, a network of veins which collects the nutrient-laden blood after absorption, and shuttles it directly to the liver.

The liver performs several important metabolic tasks in handling nutrients. Each of the major types of nutrients - carbohydrates, proteins, fats and minerals - is processed in a unique way.

Carbohydrates, or sugars, are stored as glycogen in the liver and are released as energy between meals or when the body's energy demands are high. In this way, the liver helps to regulate the blood sugar level, and to prevent a condition called hypoglycemia, or low blood sugar. This enables us to keep an even level of energy throughout the day. Without this balance, we would need to eat constantly to keep up our energy.

Proteins reach the liver in the form of their simpler building blocks - amino acids. Once in the liver, they are either released to the muscles as energy, stored for later use, or converted to urea for excretion in the urine. Certain proteins are converted into ammonia, a toxic metabolic product, by bacteria in the intestine or during the breakdown of body protein. The ammonia must be broken down by the liver and made into urea which is then excreted by the kidneys. The liver also has the unique ability to convert certain amino acids into sugar for quick energy.

Fats cannot be digested without bile, which is made in the liver, stored in the gall bladder, and released as needed into the small intestine. Bile (specifically bile "acids"), acts somewhat like a detergent, breaking apart the fat into tiny droplets so that it can be acted upon by intestinal enzymes and absorbed. Bile is also essential for the absorption of vitamins A, D, E, and K, the fat soluble vitamins. After digestion, bile acids are conserved by the intestine, returned to the liver, and recycled as bile once again.

Can poor nutrition cause liver disease?

There are many kinds of liver disease, and the causes of most of them are not known. Poor nutrition is not generally a cause, with the exception of alcoholic liver disease and liver disease found among starving populations. It is much more likely that poor nutrition is the result of chronic liver disease, and not the other way around.

On the other hand, good nutrition - a balanced diet with adequate calories, proteins, fats, and carbohydrates - can actually help the damaged liver to regenerate new liver cells. In fact, in some liver diseases, nutrition becomes an essential form of treatment.

How does liver disease affect nutrition?

Many chronic liver diseases are associated with malnutrition. One of the most common of these is cirrhosis. Cirrhosis refers to the replacement of damaged liver cells by fibrous scar tissue which interferes with the liver's important functions. This condition can occur in the late stage of many different liver disorders, including excessive alcohol intake (most common), viral hepatitis, obstruction of the bile ducts, and exposure to certain drugs or toxic substances.

Persons with cirrhosis often experience loss of appetite, nausea, vomiting and weight loss, giving them an emaciated appearance. Although it is true that many such patients have an inadequate diet, this alone does not contribute to the development of this liver disease. People who are well nourished, for example, but drink large amounts of alcohol, are also susceptible to alcoholic disease.

Adults with cirrhosis require a balanced diet rich in protein, providing 2,000 to 3,000 calories a day, to allow the liver cells to regenerate. However, some people with cirrhosis have protein intolerance. To much protein will result in an increased amount of ammonia in the blood; too little protein can reduce healing of the liver. Doctors must carefully prescribe the correct amount of protein for a person with cirrhosis. In addition, the physician can use two medications (lactulose and neomycin) to control blood ammonia levels.

What other nutritional problems are caused by cirrhosis?

When the scarring of cirrhosis interferes with the floow of blood from the portal system into the liver, a condition called portal hypertension may develop. This simply means that there is back pressure in the venous (blood supply) system entering the liver. Surgical "shunting" of blood away from the liver and into the general circulation can relieve this pressure, but it often causes a new set of problems. Because the shunted blood has bypassed the liver, it contains high levels of amino acids, ammonia, and possibly other toxins. When these compounds reach the brain, they cause a condition called hepatic encephalopathy, which means "liver-caused mental impairment."

Can nutrition be used to treat hepatic encephalopathy?

Restricting the amount of protein in the diet will generally lower the levels of amino acids and ammonia in the bloodstream. Most physicians advise their patients with this condition to eat only about 40 grams of protein a day, and will prescribe lactulose or neomycin to lower amino acid production. Certain amino acids are used in treatment, since they are considered less likely to cause mental impairment. Non-meat proteins, such as those found in vegetables and milk, are also recommended. A dietary supplement rich in these amino acids is used at many liver treatment centers.

Can diet help in treating other complications of cirrhosis?

There are a number of complications of cirrhosis which can be helped through a modified diet.

Persons with cirrhosis often experience an uncomfortable buildup of fluid in the abdomen (ascites) or a swelling of the feet, legs, or back (edema). Both conditions are a result of portal hypertension. Since sodium (salt) encourages water retention in the body, patients with fluid accumulation can cut their sodium intake by avoiding such foods as canned soups and vegetables, cold cuts, dairy products, and condiments like mayonnaise and ketchup. In fact, most prepared foods contain liberal amounts of sodium, while fresh foods contain almost no sodium at all. The best-tasting salt substitute is lemon juice.

Are there other liver diseases where specific changes in diet can help?

Nutrition and a modified diet have been found to have a significant effect on a number of other liver diseases. Some types of liver disease, for example, cause a backup of bile in the liver which is called cholestasis. This means that bile cannot flow into the small intestine to aid in the digestion of fats. When this happens, fat is not absorbed but is instead excreted in large amounts in the feces, which become noticeably pale-colored and foul-smelling. This condition is known as steatorrhea. This loss of fat calories may also cause weight loss.

Special fat substitutes, such as medium chain triglycerides (MCT oil) and safflower oil can help alleviate this condition because they are less dependent on bile for intestinal absorption. They can be used like other oils in cooking, baking and salad dressings.

Patients with steatorrhea may also have difficulty absorbing fat soluble vitamins (A, D, E, K). However, water soluble vitamins are absorbed normally. Supplementing the diet with fat soluble vitamins is possible, though it should only be carried out under the guidance of a physician.

Wilson's disease, in which large amounts of copper may build up in the body, is another liver ailment where diet can help. People with Wilson's disease should avoid eating chocolate, nuts, shellfish and mushrooms, all cooper-containing foods. Medical treatment to remove excess copper from the body involves use of the drug penicillamine.

Hemochromatosis is a disease in which large amounts of iron are transported from the intestine and accumulate in the liver. Persons with this condition must avoid iron injections, all iron-containing foods, and must be careful not to prepare food using iron utensils. Aside from these precautions, those with hemochromatosis may follow a normal diet.

What is fatty liver and is it caused by eating too much fat?

Fatty liver is not a disease but a pathological finding. A more appropriate term is "fatty filtration of the liver." It is not caused by excessive eating of fats.

Nutritional causes of fat in the liver include: starvation, obesity, protein malnutrition and intestinal bypass operation for obesity. Fat enters the liver through diet and from fat stored in the fatty tissue. Under normal conditions, fat from the diet is usually metabolized by the liver and other tissues. If the amount exceeds what is required by the body, it is stored in the fatty tissue. If fatty tissue is caused by diabetes, insulin will treat the problem. Fatty liver resulting from poor nutrition should be treated with a well-balanced diet of carbohydrates, proteins, and fats as specified by the physician.

Fatty liver can also be caused by certain chemical or drug compounds, and endocrine disorders. In these cases, the treatment would be directly related to the cause.

Two ways to avoid fatty liver: limit alcohol intake (alcohol can decrease the rate of metabolism and secretion of fat, leading to fatty liver); and watch the diet (starvation and protein malnutrition can result in fat buildup in the liver).

What lies ahead?

The relationship between nutrition and the liver is just now being realized. To what extent good nutrition and dietary practices can control or perhaps even prevent liver disease can only be surmised at this time.

Findings to date do indicate, however, that further research in this area could prove very beneficial.

How can you help?

The American Liver Foundation is a national, voluntary health agency dedicated to finding the causes and cures of liver disease. Prior to its formation, there was no organization which focused on the liver and liver diseases on a nationwide basis. This in spite of the fact that liver disease now ranks fourth as the leading cause of death for Americans between the ages of 15 and 65.

The American Liver Foundation strives to:

* provide research fellowships and encourage scientific investigators to specialize in liver research.

* organize education programs for family physicians to improve diagnosis and treatment of liver disease.

* prepare and distribute educational material about liver disease to the public.

* provide support groups for patients with liver disease and their families.
COPYRIGHT 1991 American Liver Foundation
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991 Gale, Cengage Learning. All rights reserved.

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Publication:Pamphlet by: American Liver Foundation
Article Type:pamphlet
Date:Sep 23, 1991
Previous Article:Hemochromatosis: not so rare.
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