The role of nutrition in HIV infection

Severe weight loss occurs in many people with HIV infection and is closely associated with disease progression. Wasting and chronic diarrhoea are late stage manifestations of HIV disease in Central Africa and is thought to be caused mainly by gastrointestinal parasitic infections. However, other chronic opportunistic infections, particularly tuberculosis may also be important. Such wasting undoubtedly contributes to fatigue, lethargy and reduced exercise tolerance.

Malnutrition in HIV infection and AIDS
Weight loss in HIV is a multifaceted problem. Anxiety, depression and socio-economic factors may be primary factors leading to an inadequate intake of food. Loss of appetite occurs during febrile illnesses, despite increased calorie and protein needs. Many drug treatments used for the prophylaxis or treatment of complications in HIV disease may adversely affect food intake. Diarrhoea resulting in malabsorption of nutrients occurs due to intestinal damage caused by parasitic, bacterial and viral infections. Also, it has been suggested that HIV itself may cause intestinal damage. Furthermore, protein-energy malnutrition causes a decrease in intestinal enzyme secretion and may also contribute to malabsorption.

Despite the above, many individuals with HIV infection experience periods of weight stability. Episodes of weight gain are also common during the course of the disease, particularly after treatment of secondary infections. Nutritional supplementation has been shown to increase body weight, and specifically muscle mass only in the absence of systemic infections. What nutritional advice should we give?

During the course of HIV disease each individual should be weighed at every clinic visit, the pattern of weight change should be reviewed and underlying illnesses identified. During the asymptomatic period, nutrition education should promote a nutritionally balanced diet with the emphasis on locally available energy and protein rich foods and on correct cooking methods to minimise nutrient losses. Food hygiene is important in HIV-positive individuals with poor immune function as they are at an increased risk of food poisoning. Special care should be taken with uncooked products such as eggs, fish, meat and milk products (Table 1).

• Wash hands thoroughly before handling or eating food. Avoid raw/ unpasteurised milk
• Meat, fish or chicken should always be well cooked
• Avoid raw eggs in uncooked foods eg. drinks, mayonnaise, etc.
• Discard cracked eggs
• Do not buy prepared salads with chicken, fish, meat, egg or mayonnaise from the supermarket
• Leftover food should be refrigerated as soon as it has cooled
• It should be reheated once and should be hot all the way through
• Wash all fruit and vegetables well
• Store food in a cool, dry place
• Moderate exercise should be encouraged and will assist in the toning or development of muscle.

The efficacy of most alternative diet therapies eg. anti-candida diet, macrobiotic diet, amino acid compounds, herbal mixtures, etc. have not been subjected to formal clinical research and is the subject of much debate. Many of these therapies involve food restrictions resulting in a low caloric intake.

Several vitamin and mineral deficiencies are known to affect immune function and have been reported in HIV disease (Table 2).

• Vitamin A
• Vitamin B12
• Iron
• Zinc
• Vitamin E
• Thiamin
• Vitamin B6
• Riboflavin
• Selenium
• Folate
• Vitamin C

Unfortunately there are no clinical data indicating the benefits and/or hazards of supplementing these nutrients at large doses. There is concern that megadoses may have negative effects on the immune system (Table 3).

• Vitamin A
• Zinc
• Vitamin E
• Selenium

It seems prudent for all HIV infected individuals to consume an adequate vitamin intake from food, but in those with a poor dietary intake, a multivitamin and mineral supplement should be used.
Fish oil supplementation is known to reduce cytokine production experimentally, the latter is thought to be responsible for loss of appetite and altered fat metabolism in AIDS patients. However, no studies on the efficacy of fish oil supplementation have yet been reported.

Advice on symptom control

1. Anorexia
   Oral and/or oesophageal infections e.g. candidiasis make chewing and swallowing difficult. Soft foods e.g. eggs, soup may help, and foods at extreme temperatures should be avoided. High calorie, high protein liquid supplements may be necessary if food intake is inadequate. Systemic infections increase caloric and protein needs dramatically. If patients are unable to ingest enough calories and protein orally, liquid supplements may be administered via a feeding tube.
2. Diarrhoea
   In individuals with severe diarrhoea, supportive oral rehydration therapy is essential and in the case of hospitalised patients with extensive bowel disease, specialised liquid supplements that do not require any enzyme action for nutrient absorption, may be administered. In the case of mild, intermittent diarrhoea the avoidance of milk-containing and high fat foods may be helpful. Also, caffeine -containing foods e.g. coffee, tea, chocolate and cola may worsen diarrhoea.

Conclusion

It is believed that early nutritional therapy in HIV disease result in a delayed immunological deterioration, fewer opportunistic infections and an improved quality of life.However, controlled trials are needed to define the optimal nutrition support and requirements of HIV infected individuals.

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