Nutrition and disease debate should shift to science

A balanced diet is important — but can't cure disease Copyright: Flickr/Tuey

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Science needs to be injected into the controversy over use of nutritional supplements in tackling HIV and tuberculosis, says Wieland Gevers.

An astonishing abundance of over-the-counter food supplements and food extract products in South Africa — and many other African countries — claim to modulate the human immune system to prevent or treat deadly infections such as HIV and tuberculosis.

Their presence in the marketplace has fuelled decade-long controversies about nutritional influences on immunity to the two pandemics. In South Africa, much of the coverage has, unfortunately, focused on politics and personalities. Now it should shift to science.

A panel under the auspices of the Academy of Science of South Africa has begun this process with its report released this week (22 August) based on a 16-month analysis of all the relevant research.

Healthy eating habits

One important message of the report is that there is no evidence that nutritional interventions are an alternative to using the correct medications at the correct times. (See Improved nutrition cannot replace HIV or TB drugs)

In the case of tuberculosis, this means daily anti-microbial drugs for up to six months, as soon as tuberculosis is detected in the lungs. Nutritional support is helpful, but cannot substitute for the specific drug combinations required for a cure.

For HIV, this means a lifetime on a daily combination of various antiretroviral drugs but not necessarily as soon as person is diagnosed. Drugs are administered only when there is an opportunistic infection or the immune system’s CD4 cells have dropped below a specified level.

A key issue examined by the panel is whether specific kinds of nutritional intervention can help stave off the day when drugs are absolutely required to treat HIV infections; we believe they may, but much more research is needed to be sure.

We are not saying nutrition is insignificant. Healthy eating habits still have a hugely important role to play in managing these — and other — infections. Eating a mixed diet including fruit and vegetables on a daily basis is especially important in developing countries such as South Africa where nutritional deficiencies are still rife.

The need for research

The panel noted a startling lack of well-designed, relevant studies in the field of nutritional intervention for people with HIV and/or tuberculosis, especially studies in impoverished settings.

There is an absence of evidence-based agreement on the best ways to test the extent of an individual’s malnourishment in terms of vitamins and minerals, and how dysfunctional the immune system really is.

To achieve this, the country’s top experts will have to put their heads together and update their knowledge. We need tests that are reliable, appropriate, affordable and available.

We need to establish research groups that will investigate the new discoveries being made every day about the vitamins we have had for half a century without properly understanding them. For example, vitamins A and D are now known to be intimately involved in the defence of the body against both HIV and TB.

Recent research has shown that low-grade inflammation in the gastrointestinal tract plays a pivotal role in the speed and severity of HIV infection, and may be a major driver of progression to AIDS. The intestine may well be the next focus in the search for better support of people who are HIV-infected.

The panel recommends a crash research programme involving virologists, immunologists, people specialising in inflammatory bowel disease and food technologists to establish the potential of interventions aside from those associated with conventional nutrition.

This absence of thorough research is a sad reflection in a country and continent where hunger and micronutrient deficiencies are common.

The astonishing chemical complexity of food may also be contributing to the confusion in the debate about nutrition and infections. Plants contain thousands of chemicals that help them grow and fight off predators. Some affect humans. Few are well understood.

We have recommended that tackling the absence of scientific research capacity in nutrition should be a policy priority.

Recommending caution

The panel brought together researchers, nutritionists, immunologists, biochemists, infectious disease physicians and paediatricians, policy experts and epidemiologists. The process of achieving consensus forced people into confronting the latest findings in areas outside their own specialisations.

The panel has had to pick away systematically at the legends, myths, marketing hype and salesmanship that have thrived like weeds around two of the most serious diseases facing humanity.

Many promising new avenues of research have opened up. It is possible that in the future, some types of foods may be confirmed as having the power to reduce the onslaught of HIV, especially food that dampens the inflammation caused by the virus in the gut.

But there is enough evidence at present to suggest caution where exaggerated claims are made on behalf of any food, nutritional supplement or plant chemical. And under no circumstances should anyone stop taking medically-prescribed drugs in favour of a particular diet or vitamin.

Wieland Gevers is executive officer of the Academy of Science of South Africa.

Link to the full report