Dietary intervention is normally recommended before any other intervention to control high lipid levels in adults without HIV. Similarly, dietary changes are fundamental to the management of adult-onset diabetes. However, there is little evidence that dietary interventions alone are successful in managing lipid elevations, diabetes or lipodystrophy in people with HIV, although case studies have shown improvements in lipodystrophy and metabolic abnormalities from exercise and low fat, high fibre diet. 1
Recently a Spanish team reported that a low-fat diet in people on HAART with high lipids had only moderate success. Less than half of participants complied with the dietary schedule at six months and the effects were modest. Among the compliant participants, the average cholesterol reduction was only 11% while triglycerides fell by a mean of 23%. After six months, those on a low-fat diet reported an average weight loss of 2kg. 2
A comparative study of dietary advice versus pravastatin and dietary advice found that dietary advice alone had no significant impact on levels of total cholesterol, LDL cholesterol or triglycerides, whereas treatment with the lipid lowering drug pravastatin did result in a significant reduction in lipid and triglyceride levels. 3 See below for further discussion of this study. In contrast, another small study found dietary advice produced a trend towards lower lipids of up to 7% after four weeks, and the addition of omega-3 fatty acid supplements further reduced triglycerides levels. 4
Diabetes dietary guidelines may be relevant to people with HIV who have diabetes, insulin resistance or high blood sugar. In the past, a high carbohydrate and low fat diet was recommended to all patients with diabetes but recent evidence has established that some fats actually improve blood fat profile and diabetes control in HIV-negative people. Specifically, monounsaturated fatty acids (which come from olive oil, rapeseed and peanut oils, avocados, and some nuts) and polyunsaturated fats (from corn, sunflower, safflower and soybean oils) are recommended. A diet rich in unrefined carbohydrates (from fresh fruits and vegetables, and whole grains) and high in fibre is encouraged to improve blood sugar control and lower blood lipid concentrations.
According to American diabetes guidelines, other types of fats should still be minimised. Less than 10% of total energy intake should come from saturated fats (found in butter, full fat milk, animal fat and lard). A dietary cholesterol intake of less than 30 grams a day is recommended, and trans-unsaturated fatty acids should be minimised. Trans-fatty acids are often included in margarines made from vegetable oils, and can detected by the words "Hydrogenated fat" in the labelling. Trans-fatty acids are also found in many ready prepared foods, biscuits, cakes and pizzas where vegetable oil is used.
It is crucial that dietary changes (e.g. reducing fat intake) do not reduce absorption of antiretroviral drugs, so standard cholesterol-lowering advice is not always appropriate for people with HIV. If you are considering changes to your diet, discussion with your doctor and/or a dietitian is recommended. In the UK, dietitians have recommended that individuals increase their intake of monounsaturated fat (from sources like olive oil) and reduce saturated fat intake, and cut sugar intake in order to reduce triglyceride levels. Omega-3 fish oils, present in oily fish like sardines, mackerel, salmon and pilchards, may offer some protection against heart disease. A small amount of alcohol each day may also improve levels of HDL cholesterol.
There are many misconceptions about the impact of dietary changes on lipid levels, largely fuelled by misleading advertising by food manufacturers. A review of the evidence by the British Dietetic Association highlights the following points:
- Reduction of saturated fat intake reduces the risk of cardiovascular disease, but a reduced fat diet needs to be followed for at least two years, according to large population studies, before it has any long-term impact on your risk of heart disease.
- Fat reduction has no significant effect on the future risk of death from heart attack in people who have already had a heart attack.
- The lipid lowering effect of dietary fat reduction is of the order of 3-6%.
- It is not clear whether monounsaturated fats (olive oil, rapeseed oil) are better than polyunsaturated fats at reducing lipid levels.
- There is no evidence from well designed trials that vitamin supplements, garlic or plant sterols (as found in certain types of specially designed margarine) have any significant effect on lipid levels.
- The levels of soy protein and soluble fibre needed to have a significant impact on cholesterol levels are unrealistically large.