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Chester Myers' Nutrition Series Information relating to HIV & Nutrition: HIV & Carnitine The information in these pages is about a compound called carnitine which is needed to get energy from most fats in your food. It has been shown to become low in people with HIV. There are some things you can do to help prevent being deficient in this important compound. For more on carnitine please follow this link. Good nutrition is important if you are HIV+. The information here deals only with certain aspects of good nutrition. NOTE: Pertinent references are included in References for HIV & Nutrition, part of this series INFORMation relating to HIV & Nutrition, or in a database owned by the author. A variety of studies from several countries indicates that the earliest symptom of HIV infection is deterioration of the small intestine. There are many reports of malabsorption and deficiencies of various nutrients that subsequently occur. One of the related problems is wasting, a persistent loss of weight that is not necessarily associated with opportunistic infections. This wasting results from problems in the body metabolism - low levels of vitamins and minerals, loss of the amino acids cysteine and methionine, and futile cycling of fatty acids combined with loss of body protein stores. There are reports that wasting is less of a problem among those who take N-acetyl cysteine supplements. The amino acid, cysteine, that this replaces, tends to become low in HIV disease, and this is likely at least one of the sources of wasting. Cysteine is not only one of the building blocks of the body proteins, but it is also required for production in the body of other important secondary metabolites such as glutathione. Glutathione, in the absence of supplementation with NAC, is a common deficiency with HIV. (Cysteine and supplementation with NAC are discussed in this series under the topic HIV & Cysteine.) There are now reports of low levels of another secondary metabolite. This one is called carnitine, and is likely closely associated with, if not the cause of, futile cycling of fatty acids. Carnitine is an amino acid which is available (i) in the diet, mainly from red (muscle) meats, and (ii) by synthesis in the body from lysine and methionine with the assistance of vitamin C and other secondary compounds produced in the body. The formation of carnitine in the body occurs mostly in the liver, kidney and brain. Distribution to other parts of the body, and uptake, are partly hormonally controlled. Storage of carnitine occurs primarily in the muscles. Carnitine is particularly important for heart muscle since the heart gets about 80% of its energy from lipids - see below. Although it is formed in the body under normally healthy conditions, carnitine is believed to be a conditionally essential amino acid, meaning the body may not be able to produce enough of it. This means that a dietary source of it may be important, even in the absence of disease. What may be the problem, and how is it reversed? The amino acids lysine and methionine are considered essential, meaning the body cannot make them. Methionine and cysteine are sulphur-containing amino acids, and healthy people are able to make cysteine from methionine in their livers. This means that some methionine is used to make cysteine when cysteine is low from dietary sources or when extra demands for cysteine result from certain types of stress. Both lysine and the sulphur-containing amino acids are particularly subject to destruction during food processing such that they may become no longer available for normal body metabolism. Furthermore, both cysteine and methionine have been reported to tend to be low in HIV disease. This may be because both cysteine and methionine are readily oxidized, reversibly under lower oxidation stress, but irreversibly under more severe oxidation. The irreversibly oxidized forms are not available for normal body metabolism. Carnitine is normally found at high levels in the muscles of the body. This is particularly important for supply of energy to the body muscles since carnitine transports long-chain fatty acids into the parts, called mitochondria, where they are oxidized (called ß-oxidation) to provide energy. This process also requires vitamins B2, B3, B12, and biotin. Carnitine also helps remove short- and medium-chain fatty acids that accumulate in the mitochondria as the result of abnormal metabolism. Futile cycling is the cyclical reformation of fat from free fatty acids with subsequent breakdown back to free fatty acids, and so on - thus fats are recycled burning up calories from other sources in the process. In HIV disease, the result is unusually high storage of fat. The inability to properly produce energy from fat is likely partly from problems in maintaining carnitine levels. There is likely increased burning up of protein to provide the energy that should have come from fat. Even if this does not occur, protein stores become difficult to maintain simply from the low levels of cysteine and methionine. Thus body lean mass is decreased and the body becomes fatty at the expense of protein. Since the immune system requires protein stores for its energy, this is devastating in a disease where the immune system is already under heavy siege. In the absence of HIV, the main symptoms of carnitine deficiency are high triglycerides and muscular fatigue (Siliprandi & Ciman, 1986); respiratory distress and heart disease may result. Acute encephalopathy has been noted in severe cases of deficiency (Lohninger et al, 1987). Carnitine deficiency is also associated with Reye's syndrome (Angelini et al, 1986). Carnitine supplementation has been routinely shown to help correct states of deficiency, although improvement has been noted to occur in 80% of systemic deficiencies compared to 100% of simple muscular deficiency (Ashbrook, 1986). At supplementation levels of more than 4 grams per day, diarrhoea may occur. Otherwise, carnitine has an LD50 value about the same as for other amino acids, i.e., it is considered non-toxic (Lohninger et al, 1987). Exercise also helps increase carnitine levels (Braverman & Pfeiffer, 1987; Angelini et al, 1986) with resulting increase in utilization of fatty acids by the muscles. Finally, eating more red meats should help maintain carnitine levels. What does this mean for those living with HIV? In HIV disease, it is likely that hypertriglyceridemia occurs primarily, perhaps exclusively, from carnitine deficiency. Futile cycling and low cholesterol are similarly likely results. Contribution to fatigue and wasting is also highly likely, although there are other obvious sources for these. Those who require kidney dialysis are at increased risk since low carnitine results even in the absence of HIV (Lohninger et al, 1987). It is likely that those who supplement with NAC have less severe carnitine deficiency since methionine should not get used up in helping maintain adequate cysteine levels. If these same people also maintain red meat in their diet, this also should help. For now we don't know how effective manoeuvres to replenish diminished carnitine supplies will be. There is still a possibility that the body's use of carnitine is impaired. Supplementation would seem a good idea in any case. Since there may be still a tendency for high cannibalization of protein as a source of energy, diets should not be abnormally high in fat, but instead should ensure adequate protein and carbohydrate contents, perhaps with an emphasis on elevated protein and starch contents. For those not taking NAC nor supplemental carnitine, it would seem best to keep dietary fat low, while maintaining an adequate intake of essential fatty acids. An additional advantage will be achieved if part of the dietary fat is fat composed of medium-chain length fatty acids, i.e., medium-chain glycerides of which the most common is the product called medium-chain triglycerides (MCT). Use of these by the body is possible without carnitine. Coconut oil/fat is the source of the commercial MCT product. An alternative to using the purified MCT product is therefore to use coconut fat directly. It's available in healthfood stores. If you don't find it, ask. Use it for cooking. For example, for a meat loaf, buy extra lean ground beef, and use coconut fat with it; for chicken, cut off some of the chicken fat, and replace it with coconut fat. Also, a nectar of coconut fat and pineapple is available and this is useful as a fat source in blender drinks. An added advantage is that saturated fats are less immunosuppressive than are polyunsaturated fats. A rule of thumb may be to make about 50% of the fat intake from the medium-chain length fatty acid variety. In this series:
The material in this publication is for information purposes only. It does not endorse any particular treatment program nor strategy; neither is it intended as medical advice nor as a replacement for medical advice. ©This document is copyrighted by Chester Myers. All materials may be reprinted and/or distributed without prior permission. However, reprints may not be edited. |
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March 1997 | |
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Decisions about particular medical treatments should always be made in consultation with a qualified medical practitioner who is knowledgeable about HIV-related illness and the treatments in question. MORE | |