FRANÇAIS HIV AND NUTRITION PREVIOUS PAGE NEXT PAGE SUBSCRIBE Chester Myers' Nutrition Series Information relating to HIV & Nutrition: HIV & Cysteine revisited
The information in these pages is mostly about an amino acid called cysteine. It is very important for your health. There is also some information here that can help you select some foods and supplements that can be good for you.
Good nutrition is extremely important if you are HIV+. The information here deals with only one aspect of good nutrition.
NOTE: References for this document are included in References for HIV & Nutrition, part of this series INFORMation relating to HIV & Nutrition, or in a database owned by the author.
Oxidation stress is noted to be common with HIV infection. It's logical that this decreases the supply of antioxidants in our bodies. Lipid oxidation products increase with disease progression, and there is a decline in the body's sulphur-containing amino acids, cysteine and methionine. Of the body's amino acids, these are the most susceptible to oxidation and most likely to become deficient in times of nutritional stress (Hommes et al, 1991; Millward et al, 1990; Revillard et al, 1992; Sappey et al, 1992; Singer et al, 1992; Florence AIDS Conference abstr. TuA66). Antioxidants, part of our defense system, help protect us from oxidation stress such as occurs in disease. The pool of antioxidants in a healthy body can readily cope with a disease that lasts only a few days or weeks. However, in a longer term infection, depletion in our antioxidants causes us to lose the ability to properly fight off disease. If we don't maintain our antioxidant supply, we can't expect to be healthy. Thus, as disease uses our antioxidants at a faster than normal rate, we need a larger than normal supply of them. Antioxidant supplementation has been encouraged by specialists in HIV healthcare (Bihari & Hernandez, 1993; Jensen, 1993; Lands, 1992).
Oxidation of amino acids is of particular concern since it deteriorates the body's ability to maintain its protein stores. Oxidation of cysteine and methionine occurs in two stages, the first reversibly from mild oxidation, but the second irreversibly from harsher oxidation. Under normal circumstances, if the body's supply of cysteine becomes deficient, the body makes it from methionine, but in HIV disease this is difficult due to low methionine levels.
A related problem is that most nutrients are absorbed in the small intestine, yet several studies have shown that the small intestine becomes deteriorated early in HIV infection, perhaps even before T-cells decline (Batman et al, 1989; La Brooy, 1993; Ott et al, 1993; Ullrich et al, 1989). Hence, deficiencies of many nutrients have been documented, and maintaining an adequate supply of nutrients to the body becomes increasingly of concern.
Cysteine is very important for several reasons. Some of these are as follows.
- Along with two other amino acids that are usually plentiful in our bodies, cysteine is required to make a compound called glutathione, an antioxidant that the body keeps in all its cells and is especially important for the liver and lungs. For example, the air we breathe into our lungs contains free radicals (cigarette smoke is high in free radicals!). Glutathione neutralizes, or kills, these free radicals so that they don't harm us. Studies have shown that glutathione levels decrease with HIV infection (de Quay et al, 1992; reports at San Francisco 1990 and Florence 1991 AIDS conferences). If we get enough cysteine in the correct form, then glutathione levels are maintained (Olivier et al, 1992; Staal et al, 1992). It also helps if we can keep our other antioxidants at adequate levels so that the cysteine is protected from oxidation in the body.
- Our bodies also contain a protein called metallothionein that regulates zinc and copper levels. Thirty percent of this protein is made of cysteine. Metallothionein is also an antioxidant that helps protect us from disease. This protein is particularly important for our bone marrow, thymus gland (where our T cells come from), kidneys, liver and intestines (Cousins, 1989). There have been no reports of studies of this protein with respect to HIV infection. However, if glutathione is low because of cysteine deficiency, then metallothionein will also likely be low. Again, maintaining our levels of cysteine should help maintain this important antioxidant, as well as regulate zinc and copper.
- Turnover of body protein increases in HIV infection, and this increase accelerates with disease progression (Macallan & Griffin, 1992). A decrease in any of our essential amino acids can cause problems (Millward et al, 1990). The sulphur-containing amino acids, however, are particularly critical to our health, and they are the most sensitive. A low cysteine level in the body is a source of wasting even in the absence of HIV disease. This results partly when the body cannibalizes lean body mass to maintain an important enzyme, high in cysteine content, required for digestion (Liener & Kakade, 1980). Low glutathione levels may make this wasting worse. Finally, another way in which wasting is encouraged is that when cysteine is low, the body tries to convert some of its methionine to cysteine, and this leaves less methionine which is required for making an important compound, carnitine, required in turn to get energy from fat. When carnitine levels get low with HIV infection (De Simone et al, 1992, 1993) long chain fatty acid oxidation is impaired so that the body is encouraged to burn up other compounds such as protein as an energy source, resulting in loss of lean body mass.
Then how can we help to keep our cysteine at a healthy level?
(A) In our foods, eggs and dairy are probably the best sources of cysteine, although processing of these may destroy some of it. Dairy whey proteins have been shown to help boost deficient glutathione levels (Bounous et al, 1993). Vegetables and cereals are low in the sulphur-containing amino acids, and this should be of concern for vegetarians; however, the cruciferous vegetables (Brussels sprouts, cauliflower, broccoli, cabbage) may help prevent oxidation processes, and therefore protect cysteine to some degree. It should also be noted that vegetarians will have no dietary source of carnitine since red meats are its only major source.
The severity of HIV infection makes supplementation important to consider. High levels of cysteine may be dangerous to take directly since it can be toxic to the central nervous system. Another route could be to take methionine since our body can normally convert this into cysteine. However, if our antioxidant pool is low, this mechanism is unlikely to operate efficiently. Hence, it seems reasonable to take N-acetyl cysteine (NAC) which is available as a dietary supplement, and can be used by the body to make cysteine. Information from the 1992 Amsterdam International AIDS Conference indicates that 600-1200 mg/day may be enough to maintain normal glutathione levels. Many people take up to 1800 mg/day. NAC has been used previously for bronchitis and for acetaminophen poisoning with no major toxicity problems noted. (NOTE: taking acetaminophen-containing medications such as Tylenol should be viewed with extreme caution since this encourages depletion of glutathione (Kaplowitz et al, 1989; Patten et al, 1993).)
There are other good things about NAC. There are reports that it helps block a compound called tumour necrosis factor alpha that increases to unhealthy levels with HIV infection. Moreover, NAC helps prevent a process called apoptosis where certain immune cells are destroyed (Olivier et al, 1992; Malorni et al, 1993).
(B) In order to prevent destruction of cysteine we must also keep our other antioxidants at healthy levels. Each part of our body requires specific antioxidants. Some are fat-soluble, some are water-soluble, some are needed in the membranes of our bodies, some are needed to accompany the cells of our immune system, etc. etc.. We get some of our antioxidants as vitamins, some as minerals, some are other compounds such as the pigments in vegetables and fruits, still others are made by our bodies from the food we eat.
Some of the important antioxidants, in addition to NAC, are:
- A good multivitamin with minerals should form the basis of any supplementation. This helps make sure a balance is maintained. A minimum of 25 mg of vitamin B6, 50 mcg each of chromium and selenium, and no more than 10,000 IU of vitamin A is a good rule of thumb in choosing this multivitamin with minerals.
- Vitamin C is one of the most important water-soluble antioxidants. Fruits and vegetables are good sources. Many people also take vitamin C as a supplement. It can be taken as ascorbic acid, or as ascorbates which are combined, as salts, with minerals such as potassium, calcium, and magnesium. Too much ascorbic acid in contact with your teeth can harm your teeth; if you use ascorbic acid powder that is not combined with minerals (as a salt) dissolved in water, use a straw to drink it and then rinse your mouth afterwards. Many people take 2-10 grams per day. Whatever the daily dose, it should be divided into several smaller amounts several times during the day, since otherwise you lose unnecessarily large amounts of it in your urine.
- Beta-carotene is one of the most important fat-soluble antioxidants. Your body uses this to make vitamin A which has been reported to be low with HIV. Carrots are an excellent source of beta-carotene. Many take one or two tablets a day of supplement (20,000 or 25,000 IU per tablet). It is not good to take vitamin A directly, at high levels, as poisoning can occur.
- Vitamin E is another important fat-soluble antioxidant; wheat germ contains high amounts. Above 1000 IU per day of this vitamin may not be good as there are reports that high levels can suppress the immune system. Usually, 400 to 800 IU per day should be adequate. Levels above 1200 IU are of concern since high levels may be immunosuppressive.
- The B vitamins are very important; they are high in organ meats such as liver. Folic acid and B12 are two of these that are often low even in healthy people. Deficiencies of B12 and B6 are common with HIV. One study noted that 25-35 mg/day of B6 gave significant improvements in T4 counts. B12 is best taken either as a tablet that is held under the tongue, or as a nasal gel. Your doctor can also give you an injection of it. "B complex" tablets are also available, but this should not be relied upon for B12 since the stomach route for this vitamin is especially poor with HIV infection.
- Selenium, a mineral, has also been reported deficient with HIV. It is important for proper vitamin E and glutathione functions. It may not be wise to take more than 200-400 micrograms (mcg) per day in addition to what is in a multivitamin, since high levels are toxic.
- Zinc, also a mineral, is also reported to be deficient with HIV. In HIV infection, this, B12 and selenium may decrease even when T cell counts are as high as 800. Zinc is required by over 80 proteins in the body, including stomach enzymes. It is also required by the immune system to fight disease. One study noted that 150-300 mg per day may be necessary in cases of malabsorption such as with Crohn's disease (Chandra, 1984). Since too high levels of zinc can be immunosuppressive, levels of 50-100 mg per day are probably better as routine supplementation. Recommendations were given at the 1992 Amsterdam AIDS Conference for 75 mg/day.
- Quercetin, also spelled quercitin, is an antioxidant found in many plants such as onions. It helps our body to use vitamin C efficiently. A level of 100 mg of quercetin for every gram of vitamin C that we take has been suggested. Some people take even higher levels of quercetin than this, especially if they have allergies.
- CoEnzyme Q-10 is an important antioxidant that is very basic for our health. It is fat-soluble and found in membranes. Its synthesis depends on vitamins B3, B5, B6, C and folic acid which makes it likely that it will be low with HIV infection. It is available as a supplement at either 30 mg or 75 mg size tablets. This should not be considered to be as important as basic supplementation with a multivitamin with minerals, and additional B12, zinc, C, E and NAC.
Root vegetables, leafy green vegetables, and fruits are all valuable sources of antioxidants. A few that are excellent are garlic, onions, broccoli, carrots, squash, peas, beans, Romaine lettuce, radishes, alfalfa sprouts, blueberries, blackberries, boysenberries, raspberries, apricots. If you use cooking oil, virgin cold-pressed olive oil is excellent. High levels of polyunsaturated oils are immunosuppressive, and contribute to oxidation stress (Bendich references, 1990, 1992).
Remember that you must be aware of how you react to your food, and that you are in control of what you eat. For example, if you have diarrhea, then you may need to decrease foods such as broccoli and lettuce that are high in insoluble fibre, but maintain or even increase foods such as bananas with soluble fibre. Similarly, fat intake may need to be reduced.
In this series:
- HIV & Diet revisited
- HIV & Dietary Supplements revisited
- HIV & Nutrients revisited
- HIV & Cysteine revisited
- HIV & Copper and Zinc revisited
- HIV & Vitamin B12
- HIV & Carnitine
- HIV & The Gut
- HIV & Liquid Food Supplements
- HIV & Use of Acetaminophen medications
- About Advice on HIV & Nutrition
- References for HIV & Nutrition
Author, Chester Myers, holds both honours B.Sc. and M.Sc. (1969) degrees in physical chemistry from Dalhousie University, and a ph.d. (1975) from the University of Toronto (biophysical chemistry) where he investigated the mechanism of action of a digestive enzyme. Besides publishing in the scientific literature and having authoured several patents, he has written extensively on topics regarding health and HIV. The latter include articles in The Positive Side, Canadian AIDS News, and monographs available from the AIDS Committee of Toronto (ACT), the Community AIDS Treatment Information Exchange (CATIE), and various other organizations.
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. |
