PURE study has no clear definition of carbohydrates

Interview/ Dr Soumya Swaminathan, deputy director general for programmes, WHO

Dr Soumya Swaminathan Dr Soumya Swaminathan

WHO's proposed guidelines on fats suggest that no more than 10 per cent of the daily intake should consist of saturated fat. Does that mean we should reduce whole milk, meat and eggs, in favour of plant oils and plant-based diets? While the data from the PURE study suggests that saturated fat is not associated with heart disease, do you see the WHO guidelines conflicts with the study's findings?

The new draft guidelines on saturated fatty acid and trans-fatty acid intake for adults and children indicate that “in adults and children whose saturated fatty acid intake is greater than 10 per cent of total energy intake, WHO recommends reducing saturated fatty acid intake”. This reduction can be achieved through a range of interventions, including nutrition-labelling of pre-packaged food, regulation in marketing of food and non-alcoholic beverages high in saturated fat, reformulation of food products, fiscal policies and consumer education, including recommendations to limit the intake of animal products with high content of saturated fat.

Important strengths of the PURE study are the large sample size and inclusion of populations from a wide variety of countries and regions throughout the world. However, pooling together of such diverse populations with diverse dietary patterns and other factors would pose some challenges with respect to interpretation of results. A key limitation is not having a clear definition of carbohydrates (CHO) in the paper. So, it is not clear which CHO was included in the analyses. In other words, they did not seem to have made any distinction between CHO which have been shown to be detrimental to health (eg. free sugars, refined grains) and those which have been clearly shown to have health benefits (eg. fibre rich wholegrains, legumes, vegetables and fruits).

Another interesting observation is related to the characteristics of the study participants, in particular, the average intake of CHO, total fat and SFA of the baseline population. They varied from region to region, but they are all within the recommended ranges regardless of where they come from.

As far as the presented analyses are concerned, a major difficulty is their interpretation. For example, for CHO, Quintile 4 and 5 consumed much more than current recommendations of WHO or many other countries (i.e. Quintile 5 median is over 77 per cent of total energy intake. That most likely means little intake of any other essential nutrients which has an impact on the health status of the people). And in the same way, for total fat, the actual intake of Quintile 1 and 2 are much less than current recommendations of WHO or many other countries. So if the analyses presented in the paper compares the two ends of these extremes, they seem to be quite biased.

In the context of India, or even other low and middle income countries, wouldn't a fruit and vegetable based diet be biased against the poor who can not afford 4-5 servings of fruits and vegetables?

Public health recommendations to consume adequate amounts of fruit and vegetables need to be supported by agricultural and trade policies, aimed at improving the availability and affordability of such products (for example, redirection of agricultural investments, support to smallholder farmers, improvement of supply chains, public food procurement policies, inclusion in social benefit packages, etc).

How good do WHO guidelines on diet hold in a country such as India, where our incomes and other parameters (body constitution, locally available foods, diet patterns) would be vastly different from western countries?

WHO guidelines are based on systematic reviews of the available scientific evidence, and consider research implemented in different parts of the world. If contextual factors need to be taken into account, this is usually specified in the guidelines. Healthy diets have very similar characteristics throughout the world. As recommended by WHO, a healthy diet starts with exclusive breastfeeding for the first six months. It is a diet that allows to balance energy intake with energy expenditure; keeps total fat intake to less than 30 per cent of total energy, has less saturated fats and more unsaturated fats; does not contain industrial trans-fat; does not have more than five per cent of total energy intake from free sugars; keeps salt intake to less than 5g/day and has at least 400g of fruit and vegetables. The implementation of the guidelines need to consider the specific characteristics of the food system, including food culture. Food systems, including in India, have not always been able to meet the needs of the population, thus generating food insecurity and different forms of malnutrition. Agricultural, trade, health and social policies need to be used by governments to guide food system transformation to make healthy diets available and affordable.