Fat, fibre intake linked to metabolic upsets in PI patients

An American study has found that high intakes of polyunsaturated fats and alcohol, and a low fibre intake are strongly associated with metabolic abnormalities seen in the lipodystrophy syndrome in people with HIV.

The Boston based study recruited 62 men and 23 women with HIV who were taking antiretrovirals and had signs of body fat redistribution. Seventeen HIV-positive men without evidence of body fat changes and 35 HIV-negative men were also recruited as controls. The average ago of the people on the trial was 42, and the average time of HIV infection was a little over seven years. 41 percent had a viral load below 400 copies m/L.

After an overnight fast, blood tests were taken to examine insulin, cholesterol and other blood fats, and physical examinations were conducted to examine body fat distribution, including DEXA scans. Details of diet were also recorded.

The results showed that age, and use of protease inhibitors, were strongly associated with insulin resistance. It was also discovered that people who had both fat wasting in either the face or limbs (lipoatrophy) and increased fat deposits around the trunk or neck (adiposity) were significantly more likely to have elevated insulin and blood lipids.

Moreover, the study also showed that dietary habits could also have a significant impact on the metabolic abnormalities seen in lipodystrophy, independent of other recognised risk factors such as age and use of protease inhibitors. However, diet was not seen to have any impact on body fat redistribution.

High consumption of fat, low dietary fibre intake and alcohol consumption were all associated with increased blood fat levels and insulin abnormalities. In particular, high polyunsaturated fat intake was a significant predictor of higher insulin levels. A low fibre intake also seemed to contribute to increased insulin levels, but did not impact on other lipids. High alcohol consumption was associated with the highest cholesterol levels.

Of the 85 people enrolled on the trial, 53 percent had a dietary fibre intake lower than the daily 20 g recommended by the American Diabetes Association, and an increase of just five grams of dietary fibre a day was associated with a 14 percent decrease in insulin. However, fibre intake was not correlated with lipid abnormalities.

The study also indicated that people with mixed lipodystrophy (a combination of lipoatrophy and adiposity) were more severely affected by insulin resistance. Also, those experiencing fat loss had a higher daily calorie intake than those with either abnormal fat accumulation or a mixture of fat accumulation and wasting. The study authors commented that they were seeing a "spectrum of metabolic disturbances".

The researchers established that women were particularly likely to have a low fibre intake, and that HIV-positive men were more likely than their negative peers to have increased cholesterol consumption and to obtain more of their daily calorie intake from protein. Positive men with body fat changes were more likely than HIV-positive men with no signs of body-fat abnormalities to have higher blood lipids and insulin levels.

The report study authors concluded: "Our data indicate the certain modifiable dietary components, such as polyunsaturated fats, fibre and alcohol, are strongly associated with insulin resistance and hyperlipidemia among these patients independent of age, sex, protease inhibitor use, and body fat distribution...further investigation is needed to assess the impact of dietary intake and its modification on metabolic risk factors in HIV-associated fat redistribution."

The authors note that some dietary changes may be a consequence of modifications that occurred as a result of a changing need for calories due to body fat changes (in particular, lipoatrophy). They suggest that a prospective study (which follows people before they develop metabolic or body fat changes) may help to establish the extent to which pre-existing dietary patterns influence metabolic changes.