February is quiet, cold and sombre here in France – days tiptoe stoically through the winter, wistful for spring and warmth. But there is always news that catches the eye after freezing walks with my dog and here are a couple of recent items.
An important non-story
February 14 this year was a curious day. It was the day the British Foreign Secretary gave a ridiculous speech trying to justify Brexit – it was also Valentine’s Day and the first anniversary of my mother’s death. More relevantly, the prestigious British Medical Journal published a significant French study on the impact of processed foods – it is loquaciously called “Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort”.
It should be the best kind of study: large-scale (104,980 participants), long-term (eight years) and wide in scope (covering some 3,300 different food items). I am a sucker for such complex studies because they usually provide a lot of data, and huge volumes of data suit my penchant for analysis.
The sobering headline finding, quoted verbatim, was “a 10% increase in the proportion of ultra-processed foods in the diet was associated with a significant increase of greater than 10% in risks of overall and breast cancer”. This is relevant as the World Health Organization had categorised processed meats in 2015 as Group 1 carcinogens (along with plutonium, tobacco, asbestos, etc) – their statistics indicate that eating 50g of processed meats daily increases the chances of developing colorectal cancer by 18%, raising the risk from 6% to 7% overall for bowel cancers in Britain. If you are curious, please read this article.
So to link a 10% increase in consumption of ultra-processed foods (UPF) with a 12% increase in overall cancer rates and 11% increase in breast cancers is indeed disconcerting. This implies that a persistent 20% increase in UPF consumption can result in a serious 24+% increase in overall cancers, easily qualifying UPF as a Group 1 carcinogen after a certain consumption threshold.
Reviewing the data in detail finds that the problem food items investigated falls into the NOVA Group 4 classification. NOVA is a name, not an acronym, and Group 4 includes highly-processed industrial foods, usually with five or more ingredients including sugar, oils, fats, salt, antioxidants, stabilisers, colourings, bulking/anti-bulking agents, emulsifiers, humectants, industrial flavourings, artificial sweeteners, preservatives, etc – basically, many compounds that you would not find in your average home kitchen.
Examples of NOVA Group 4 foods include “mass produced packaged breads and buns; sweet or savoury packaged snacks; industrialised confectionery and desserts; sodas and sweetened drinks; meat balls, poultry and fish nuggets, and other reconstituted meat products transformed with addition of preservatives other than salt (for example, nitrites); instant noodles and soups; frozen or shelf stable ready meals; and other food products made mostly or entirely from sugar, oils and fats, and other substances not commonly used in culinary preparations such as hydrogenated oils, modified starches, and protein isolates” – in short, many of the foods sold in supermarkets.
The study spanned eight years and covered 104,980 participants aged between 18 and 73 years, of which 78.3% were women (men apparently did not complete their surveys as diligently as women). The monitored diets were graded – ranging from normal to high UPF content and the impact of UPF was surmised from the study results. Also noted was that people consuming high levels of UPF tended to be younger, smoked more and exercised less – this will be reflected upon later.
One immediate puzzling statistic was the lack of a strong link between UPF and colorectal cancers – one would have thought a lousy diet full of additives would have at least a similar impact on bowel cancer as processed meats. Even the report mentioned that “food preserved with salt are associated with an increased risk of gastric cancer” as are foods with a low dietary fibre – but there was no conclusive statistical link recorded.
Another curious issue is the manner data is collated. After an initial comprehensive survey, research data was collected by randomly asking participants to fill in online surveys of daily food consumption over a two-week period, specifically tracking 3,300 different food items. This method can therefore exclude other foods which may also have health impacts – and does not eliminate the possibility that things can go unreported from such a large list of items. However, it is understandable why this novel method was elected – large scale epidemiological studies are notoriously difficult to manage and the researchers probably had reasons for their approach, perhaps relying on the large numbers of participants to smooth out any outliers.
Some lifestyle analysis was included, though it did not appear rigorous. For example, it is not possible to differentiate light smokers from heavy smokers, or whether people are on medications. The focus on NOVA Group 4 foods was too general, and does not analyse the impact of additives or combinations of additives. Other dietary-related issues (eg. diabetes, hypertension, and cholesterol) were not investigated, nor were items such as pesticide or BPA residues – cancers can also take more than eight years to develop. Notably, the transition effect of moving away from high UPF to better diets was not captured. However, to be fair, the researchers did try to adjust the statistics for certain variables (eg. body mass index, use of oral contraception, even family cancer histories), though none of their adjustments made any difference to the headline numbers.
So after an afternoon of poking around various sets of data, the only relevant statistics are that eating UPF increases the overall probability of getting cancers – and these probabilities are quantified at between 11% and 12% for a 10% increase in consuming NOVA Group 4 foods. More than this, we cannot say – and even so, there may be confounding factors affecting the statistic (eg. it is indeterminate how lifestyles affected the results) and the baseline level of UPF consumption was also not definitively prescribed.
Nevertheless, it is now indisputable that there is a link between cancers and ultra-processed foods – it is NOT suspicions, hunches or educated guesses anymore.
Overall, this is probably not earth-shattering news, almost a non-story (as the statistics are not surprising) – and we are still no wiser as to which compounds/components in foods are active carcinogens. But it does highlight we are far from understanding the impact of additives and processed foods on health – and more research is needed to make sense of the increased disease probabilities. But this study is a kick in the right direction, and a well-founded confirmation that over-consumption of UPF tangibly increases cancer probabilities. It therefore makes sense to watch what and how much we eat – and a good way to avoid UPF is shunning foods with too many additives/ingredients.
Alcohol and living longer
Other news is the latest claim from The 90+ Study (a research project started in 2003 covering around 14,000 participants) that modest consumption of alcohol improved the chances of people living past the age of 90 – two daily glasses of beer/wine is alleged to be better for longevity than regular exercise.
Reading the papers from the University of California raised some points – the study only covered people living in the California Leisure World retirement community (which therefore immediately incorporates an income and lifestyle bias). The latest study also only investigated 1,700 people who were already at the age of 90 or older – hence there may be a genetic longevity bias as it automatically excluded everyone who had died before age 90. However, an earlier 2007 paper from the same study also claimed a 15% reduction in mortality for younger retirees who had two or more alcoholic drinks a day.
There is only speculation as to why alcohol might be beneficial. One theory involves the recently-discovered glymphatic system (GS) in the brain, which is regulated by the hormone norepinephrine – this system increases the flow of cerebrospinal fluid when we sleep and acts as a waste clearance mechanism, flushing toxins and damaged proteins such as beta-amyloid and tau tangles out of the brain. Not providing time for the GS to finish its housekeeping is a plausible explanation why we feel bad after too little sleep. It may be that alcohol can improve the function of the GS in some unknown manner, possibly by relaxing the brain – or it may be that casual drinkers eat better or have more sociable lifestyles.
However, before we get excited, there are other findings. People who drink two or more cups of coffee daily also live longer as do people who are mildly overweight (not obese) in their 70s. Over 40% of people aged 90 or older also have dementia and almost 80% are disabled in some manner – making one wonder how they get their daily two glasses of booze.
The news media’s headline focus on alcohol’s impact on longevity might therefore be misleading – though it is an interesting subject to contemplate over a bottle of wine.