Alex Speers ND, MS
When making dietary recommendations to patients with cancer, naturopathic doctors often emphasize whole foods as part of their overall treatment plan. Whole foods have been minimally processed or refined and are free from additives and other artificial substances. Organic fruits, vegetables, nuts, and whole grains are all examples of whole foods, each densely packed with a variety of beneficial nutrients.
On the other end of the spectrum are processed foods, which have undergone numerous physical, biochemical, and/or chemical processes and which are often higher in saturated fat, added salt and sugar, and lower in fiber and vitamin density. Due to the way in which processed foods are made and packaged, they also often contain unwanted contaminants and additives, some of which are potentially carcinogenic. Given these descriptions, it’s probably easy to understand why naturopathic doctors consistently recommend that patients with cancer prioritize whole foods within their diet. Interestingly, however, there is still uncertainty regarding the long-term health effects of processed foods, including their impact on cancer risk.
A recent study, published in the British Medical Journal, sought to investigate this question. The authors conducted a prospective cohort study, which means there was a group of participants that the researchers followed over time. It was a large study (104,980 people!) and the participants were followed for 8 years (2009-2017). During this time, participants were asked to fill out at least two 24-hour dietary recalls (i.e. questionnaires detailing everything participants had eaten in the previous day). Based on these questionnaires, researchers categorized foods into different categories, with a focus on “ultra-processed foods.”
“Ultra-processed foods” is a relatively new term developed by a group of researchers and included in NOVA, a food classification system that categorizes foods based on how processed they are. Other food groups included in NOVA are “Unprocessed or minimally processed foods,” “Processed culinary foods,” and “Processed foods.” If you’re interested in what foods are included in each category, a free overview of the NOVA system can be found here: NOVA.
The researchers then sought to investigate whether the amount of ultra-processed food in a person’s diet was associated with their risk of cancer. What the researchers found was that for every 10% increase in the proportion of ultra-processed food in a person’s diet, that person had a 12% increased risk of cancer. So, for example, a person whose diet was 20% ultra-processed foods would have a 24% increased risk of cancer, compared to someone who had no ultra-processed foods in their diet. These are concerning findings given that previous surveys have indicated that ultra-processed foods contribute to between 25% and 50% of total daily energy intake for the average person.
Because this study was observational, we cannot definitively state that ultra-processed foods increase a person’s risk of cancer. There may be other factors at play, though the researchers did control for things like physical inactivity, smoking, alcohol intake, etc. In addition, it’s important to acknowledge that the study relies on the participants to accurately record their food and the researchers to accurately categorize that food. It’s unlikely that this process was perfect, which could have influenced the results. On the other hand, this was a massive study and there is pre-clinical evidence suggesting that many of the compounds found in ultra-processed foods are potentially carcinogenic. Given this, it makes sense to significantly restrict our intake of ultra-processed foods and emphasize whole foods in our diet wherever we can.
Fiolet T, Srour B, Sellem L, et al. Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort. BMJ. 2018;360:k322.
DISCLAIMER: These statements have not been evaluated by the Food and Drug Administration. There are no financial ties to any supplement companies, pharmaceutical companies, or to any of the products mentioned in this post. This post is not meant to treat, cure, prevent, or diagnose conditions or diseases and is meant for educational purposes. As always, please consult your doctor before trying any new treatments or supplements.
