Written by Dr Catherine Zollman, Medical Director, Penny Brohn UK

For more than 35 years, Penny Brohn UK has promoted healthy eating as one important way of helping to reduce the chances of cancer developing, recurring or progressing.

We have always recommended that people limit the amounts of heavily processed foods they eat, and that, where possible, they choose a more wide range of fresh and less-processed foods, which contain a much greater amount and variety of essential nutrients.

On February 14 the British Medical Journal published the findings of an important study: The consumption of ultra-processed foods and cancer, which gives further support to Penny Brohn UK’s position, and re-emphasises the role that diet can have in changing cancer risk.

Researchers looked at the intake of processed foods by more than 100,000 people in France and Brazil. The results showed a 12% increase in the overall rate of cancer, and an 11% increase in the rate of breast cancer, in those with the highest intake of “Ultra-Processed” foods.

Ultra-processed foods are at the most highly industrialised end of the food spectrum and are typically prepared using industrial processes like “hydrogenation”, which are a far cry from the cooking methods used in a home kitchen.

They often have long lists of chemical sounding additives and ingredients which are sometimes known by their individual “E-numbers”. These act as colourings, flavourings, sweeteners, preservatives, emulsifiers, flavour-enhancers etc.

Ultra-processed foods also tend to contain lots of refined sugars and carbohydrates, salt and unhealthy, damaged fats. Products like confectionary, many packets of sweet and savoury snacks, mass produced bakery products and biscuits, chicken or fish nuggets, processed meat products, instant desserts, drinks, noodles and soups, long shelf-life margarines and sweetened fizzy drinks all fall into this category.

Food journalist and author, Michael Pollan, calls these “Edible Food-like Substances” and warns us not to confuse these with “Real Food” which provides the nourishment we need, in a form more suited to the way our bodies have evolved. Alarmingly, research shows that ultra-processed foods make up between 25% and 50% of the average UK person’s energy intake.

Although the researchers admit that study has some limitations, their results suggest that it isn’t just that Ultra-processed foods are mostly “empty calories” that contain little in the way of useful nutrients, but that some aspect of the processed food itself is likely to be positively carcinogenic and damaging to our health.

There are a number of possible reasons why, and the researchers explore some of these in their article:

Ultra-processed foods do not support a healthy gut environment. We need a wide range of different bacteria in our guts for our digestion and immune systems to work well. When we restrict our diets to highly processed foods, the diversity and amount of our healthy gut bacteria (our microbiome) decreases rapidly and dramatically.

The combination of additives in ultra-processed foods may be carcinogenic. While the levels of individual additives in any one food product are controlled by government safety legislation, there is no control of the number of different additives which can be added to a food, and we often eat foods in combination, so a “cocktail effect” where smaller amounts of different chemical additives may combine to produce dangerous effects cannot be ruled out.

Some of the industrial processes involved in making Ultra-processed foods may damage ingredients like sugars, fats, proteins and amino-acids so that they become more hazardous to health. N-nitroso compounds, acrylamide, heterocyclic amines and polycyclic aromatic hydrocarbons are just some of the by-products that can be produced during food manufacture.

Ultra-processed foods are often in close contact with, and are designed to be heated in, synthetic packaging materials. Harmful chemicals from the packaging (like the hormone disruptor Bisphenol-A, or BPA) may leak into the food especially during the heating process.

When we eat ultra-processed foods our blood sugar levels can rise rapidly, triggering the release of insulin-like growth factors which are associated with increased cancer risk.

Eating a lot of ultra-processed foods means we usually eat less of the more healthy foods, like naturally colourful vegetables, fruits, herbs and spices, wholegrains, oily fish, nuts and seeds that contain helpful plant chemicals and protect our cells from damage and reduce our cancer risk.

An important milestone

The findings of the BMJ paper are an important milestone for anyone trying reduce their cancer risks, but it’s important to realise that not all food that is ready-made or that we buy in packaging is a hazard.

Many pre-prepared foods contain fresh ingredients and have been minimally processed. If it looks like something you could make in your kitchen, it probably is, and it wouldn’t count as ultra-processed! Just check ingredient labels carefully for those long chemical additives, and pick products with ingredients that you recognise in a form that resembles something that you could imagine making yourself – tinned tomatoes are usually pure tomatoes that have been blanched and peeled; a portion of chicken curry may contain a lot of delicious vegetables, herbs and spices with no artificial additives.

Hopefully this new research will provide you with a bit more of the evidence and motivation you need to treat your food and drink like medicine – which can have powerful positive, and sometimes powerful negative effects, on your health – and as one of many tools you can use to help you keep living as well as possible for as long as possible. And eating less processed foods generally means less plastic packaging, which is good for the environment too….

The Bristol Whole Life Approach

Food and nutrition form an essential part of our Bristol Whole Life Approach. Our healthy eating plate shows the type and proportion of foods to include at each meal.

Aim for at least half of your plate to be filled with vegetables & fruit, with the remainder being split between protein, fats and starches (grains/potatoes).  Don’t forget to include herbs and spices, which are central to our plate because they are a rich source of anti-inflammatory and anti-cancer properties, and give flavour and interest to our meals.

And last but by no means least, is our mindful eating principle. We believe that how you eat is as important as what you eat.  Mindful eating helps us to digest and absorb what we eat and makes eating more enjoyable.  So, next time you eat, try making your dining area a pleasurable place to be and take time to sit, eat, chew and savour your meal.

You may also like:

How to eat the rainbow

More info on eating well

Read our healthy recipes

Soothe the digestive tract

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