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A group of Australian and Spanish researchers have published a systematic review and meta-analysis looking at the association between consumption of ‘ultra-processed foods’ and various health outcomes. The review included 43 observational studies and found that consumption of ‘ultra-processed foods’ was associated with an increased risk of overweight, obesity, abdominal obesity, all-cause mortality, metabolic syndrome and depression in adults. An association was also seen between consumption of ‘ultra-processed foods’ and cardiometabolic diseases, frailty, irritable bowel syndrome, functional dyspepsia and cancer.

Considering ‘ultra-processed foods’ make up a large proportion of the foods on our supermarket shelves, these findings appear concerning. However, the review included studies which used the NOVA food classification system to define ‘ultra-processed foods’, and as discussed elsewhere in this edition of GI News, there have been some questions raised about the functionality of NOVA in its current form (see Perspectives). The NOVA classification defines ‘ultra-processed foods’ as formulations of food substances (ingredients you wouldn’t typically find in your home kitchen), often combined with additives designed to make the food palatable, and which are typically created by series of industrial techniques and processes. However, within the NOVA classification, foods defined as level 4 (‘ultra-processed’) can vary widely in their nutrient composition and the current classification doesn’t allow us to determine whether the associations observed between consumption of ‘ultra-processed’ food and health are due mainly to the structure of the food (i.e., mechanical processing) or the composition (i.e., specific ingredients and additives).

The review also only included observational studies which show an association between consumption of certain foods and disease risk, but which can’t prove cause and effect. To date there is a lack of randomised controlled trials looking at the long-term impact of ‘ultra-processed foods’ on health outcomes and disease risk.

Processing of food isn’t a problem in itself. In fact, most of the foods we eat are processed in some way before we eat them. Techniques such as heating, pasteurizing, canning and drying are all forms of processing, which can help to make foods safe, edible and more suitable for storage. Examples include canned legumes, frozen vegetables, pasteurised milk, canned fish and even freshly made bread. Further high-quality research is needed to determine how to best define ‘ultra-processed foods’ and the differences in health outcomes between minimally processed and ‘ultra-processed foods’.

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Dr Kate Marsh is an is an Advanced Accredited Practising Dietitian, Credentialled Diabetes Educator and health and medical writer with a particular interest in plant-based eating and the dietary management of diabetes and polycystic ovary syndrome (PCOS).

Contact: Via her website www.drkatemarsh.com.au