Abstract
In resource-poor countries with limited access to highly active antiretroviral therapy (HAART), the number of people dying from AIDS is expanding rapidly. 1 The alarming death rates are a consequence of the combined effects of opportunistic infections, malnutrition and wasting in HIV disease. 2 Several studies have shown that weight loss and wasting (usually defined as loss of at least 10% of body weight) is significantly associated with accelerated disease progression and increased mortality in HIV infection. 3 In addition, with significant wasting, affected individuals are unable to carry out their normal activities which may worsen the stigma of already marginalized HIV-infected individuals. 4
A significant risk factor for wasting in HIV disease is intestinal dysfunction and subsequent nutrient malabsorption. 5,6 Malabsorption causes decreased appetite as a consequence of the ‘enterogastrone’ effects including dry mouth, decreased gastric acid secretion, decreased gastric emptying rate and slowed intestinal transit. Decreased appetite leads to poor intake of food that further jeopardizes maintenance of weight. 7 We wish to draw the attention of clinicians treating HIV-infected individuals to malabsorption as a potential contributory cause of wasting in HIV disease.
In HIV disease, the small intestine is typically affected either as a result of opportunistic enteric infections leading to intestinal dysfunction, or due to the direct effects of the HIV virus, causing malabsorption of most nutrients and subsequent wasting. 8,9 Cryptosporidium, as well as Microsporidia and Isospora, are common opportunistic parasites that may cause serious gastrointestinal infections, intestinal damage and chronic malabsorption. 10,11 Intestinal opportunistic infections are more common in patients with CD4 counts less than 180 cells/mm3. 12,13
Further studies have shown that fat malabsorption is the most frequent problem in HIV disease (seen in 25–90% of infected people) and the frequency of fat malabsorption increases as the disease progresses. 14,15,16 Fat malabsorption impairs utilization of dietary fats which are food with a high calorie density. It causes abdominal symptoms such as diarrhoea and bloating which may further reduce food intake, and may be associated with micronutrient deficiencies from loss of fat-soluble vitamins. Micronutrient deficiencies further contribute to impaired immunity, rapid disease progression and increased mortality. 17
It is imperative to prevent wasting in HIV-infected patients to reduce morbidity and mortality and improve the patient's quality of life.. In resource rich countries, the physician would have access to sophisticated laboratory investigations to assess intestinal function and be able to administer the most appropriate treatments, whereas in resource-poor settings malabsorption is often not recognized due to the lack of diagnostic facilities. Even without specific diagnostic facilities, it is possible to treat the common causes of malabsorption, maintain energy balance and improve nutritional status by taking into consideration the loss of specific nutrients such as fat-soluble vitamins due to malabsorption.
Every episode of diarrhoea should be carefully assessed with a detailed clinical history. If available, simple laboratory tests should be performed on stool samples including: examination for ova, cysts and parasites using wet saline mounts; a formol ether concentration method with Lugol's iodine for the detection of cysts, ova, trophozoites and larvae of intestinal parasites; and a modified Ziehl-Nielsen staining of stool smears to identify Cryptosporidum parvum and Isospora belli.
Nutritional therapy, including aggressive dietary counselling and oral supplements, are the mainstay in the management of wasting associated with HIV. An increase in energy intake of 500 kilocalories above the daily requirements will result in an average gain of 1 lb per week. 18 The recommended dietary allowance of protein for persons aged 25–50 who are in good health is 0.8 g/kg body weight per day. 19 For HIV-infected people with significant wasting, a protein intake up to 1.5 g/kg body weight may be advised. However, Carbonnel et al. 20 demonstrated that what differentiates HIV-infected people with malabsorption from HIV negative patients with malabsorption is their inability to increase energy intake enough to overcome intestinal losses. Thus, an HIV-infected person may appear to consume an adequate amount of calories but still not increase his oral intake sufficiently to overcome intestinal losses. Those patients with inadequate oral intake may benefit from six or more small meals throughout the day, rather than three large ones. For those with diarrhoea, a lactose-free, low fibre, semi-solid diet should be recommended.
In order for any person to maintain a stable weight, the energy intake must equal energy losses and total energy expenditure over time. 21 However, HIV-infected patients in resource-poor countries commonly confront difficulties with access to sufficient good food because of financial constraints and poor social support. Issues relating to access to good food and social support should be addressed by individual countries with social and food security schemes for HIV-infected individuals.
Micronutrient supplements are believed to protect the integrity of the gastrointestinal epithelia irrespective of whether the damage is caused by enteropathogens, or by HIV disease per se. Zinc plays a crucial role in maintaining the integrity of epithelial cells that line the intestine and preventing diarrhoea in HIV-infected individuals. 22
In conclusion, nutrient malabsorption as a cause of wasting in the context of HIV infection should be addressed with close attention to treatment of opportunistic enteric infections, and to energy intake and weight gain. Addressing the underlying HIV infection and immunosuppression with appropriate antiretroviral therapy will further improve intestinal function, reduce the burden of disease and promote an improved quality of life in HIV-infected individuals.