Food Processing: Another Suspect in the ‘Globesity’ Epidemic?
Last night, I read an article that fit absolutely perfectly into my unintentional but prominent theme of the last couple of weeks: the relationship of the microbiome to weight issues…and to food: “Food Processing, Gut Microbiota and the Globesity Problem.”[i] Yup – we face an epidemic of“globesity”! Great word, right?!
In fact, on the subject of globesity, the article’s first sentences point out some depressing statistics: “In 2016, 39% of the global population aged 18 years or older was overweight and 13% was obese. Elevated BMI, a parameter of obesity, is a risk factor for NCD [non-communicable diseases], which include cardiovascular disease (CVD), cancer, respiratory diseases and diabetes. CVD alone cause 26.9 million deaths per year and all NCD combined cause 71% of the world annual deaths…”
Remember: as I pointed out earlier this week, there is no one truth and the article emphasizes that we simply do not yet know all the factors that are feeding (ugh..another inadvertent pun by Judy!) into the obesity epidemic. And when it comes to some of the most likely culprits, we don’t yet fully know any mechanisms of action. So what I’m about to report is a status update on some ongoing research…it is not THE answer.
To emphasize this point, I want to share with you a quote from the article that sums this sentiment up: “The development of the global obesity problem has triggered researchers worldwide to study the effects of human dietary and lifestyle patterns on energy balance and body weight trends…How and why this energy disbalance occurs so widespread and why this phenomenon seems so difficult to control or counteract is subject to research all over the world.” Scientists are working to figure it out but as yet, there are unfortunately, no definitive answers.
One of the likely culprits though appears to be the way in which food is commonly processed in the industrialized world: “The development of a so-called Western dietary pattern has been strongly related to the obesity problem and can be attributed to major worldwide changes in the agro-industrial systems. Since 1850, but especially after WWII, sucrose, high fructose corn syrup (HFCS) and vegetable oils are increasingly produced and consumed, strenuous milling and sieving of grains has led to highly refined four without fiber or germ…and the practice of feeding grain to cattle instead of grass provides us with meat with higher saturated fat contents than wild or pasture-fed animals could deliver.”
So what we know is that the way our food is prepared has radically changed in the last 150 years, especially in the last 70 years or so. And highly processed food is calorie dense and nutrient deficient, exposing us to markedly greater levels of unhealthy fats, sugar, salt – and increasing low amounts of fiber. And this shift entirely parallels the increase in obesity.
The authors emphasize what is now accepted as fact and what is still hypothesis or conjecture and I will let you know what’s what, as I hit the high points for you.
- It is accepted as fact that the gut microbiome plays a pivotal role in obesity, but what is more important than individual species is the “changed functionality” of the microbiota meaning an obese person’s bacteria are more adept at pulling calories out of food (which they refer to as “increased energy harvesting”), as well as affecting other pathways that alter signals of satiety (feeling full)…and of course, affecting the immune system: “Impaired mucosal and intestinal barrier function in obesity, for instance, leads to closer contact between gut bacteria and their host, increasing the bacteria’s potential to cause inflammation. Also, inflammatory bacterial components…can more easily enter into the blood circulation, leading to low grade systemic inflammation. This feature is regularly mentioned as a key and common aspect of metabolic diseases, like type two diabetes, cardiovascular disease, impaired glucose and lipid metabolism…” Leaky gut rears its ugly head yet again.
- There is not a huge amount of research into the effects on weight of micronutrient deficiency. Heavily processed foods are very low in vitamins and minerals and some recent studies have suggested that this may be a factor. For example, deficiency in vitamin A has been “related to increased adiposity and body weight gain.” Some antioxidant vitamins like E and C, beta-carotene, and the mineral, selenium, influence the secretion of a chemical called leptin by fat cells, which is known to regulate appetite and fat deposits. It’s also important to recognize that our gut bacteria are also reliant upon the intake of adequate micronutrients, and deficiencies are known to be associated with biome alterations. Several studies have shown that, for example, “…diets deficient in vitamin A, zinc, folate or iron shift the gut microbiota composition…”
- Ultra processed food have a much higher density of calories, and while high in fat and sugar, they are low in fiber and water, which have little to zero calories. Both water and fiber too, increase feelings of fullness. So while eating many calories in a highly processed food diet, people still tend to feel more hungry longer…and thus continue eating more. Fiber too feeds gut bacteria and thus, increases production of not just anti-inflammatory short-chain fatty acids, but also the production of hormones that induce feelings of satiety. Multiple studies have been conducted that show that people feel markedly more full eating an equal amount of less processed food (for example, whole grain oat porridge) versus highly processed foods (like ready-to-eat breakfast cereals).
- Food additives started to be used back in the 1800s, and since then, we have increased the amounts so that now, over 2500 different additives are present in the food supply. There is inadequate data still on how these add to the obesity epidemic and worse, most have not been evaluated in terms of their effect on the human gut biome. What we do know right now:
- There is suspicion, but no definitive proof yet, that artificial sweeteners (like sucralose and aspartame) may be a part of the obesity picture. However, we do have some convincing evidence that they are bad for the gut bacteria. The most convincing study to date was conducted in Israel in 2014 and consisted of adding aspartame, saccharine or sucralose to food or water of mice. The results showed “…significant effects on gut microbiota composition, paralleled with increases in glucose intolerance…Saccharin showed the most pronounced effect….” Further studies are now being run.
- Emulsifiers are suspect but not nearly enough research has been done. Some appear to cause gut inflammation by allowing the gut bacteria “translocate” (i.e. move) into the lining of the gut. Some also seem to cause loss of bacterial diversity.
- Back to our old friend, high fructose corn syrup (HFCS), which you’ll remember, I wrote about back in February and then again, wrote more about back in March, “Consumption of HFCS has risen sharply over the last decades, from .292 kg per person per year in 1970 to 33.4 kg per person per year in 2000, absolutely paralleling the rise in obesity.” The link to obesity may be due to the increased calorie consumption, with all that added sugar, but there are other factors at play. For example, the article points out that fructose is metabolized differently than glucose, and is more prone to being converted into fat. More than that, as you all know, if you regularly read my blog, HFCS effect on the gut bacteria is being studied right now, and thus far, research points it to causing major alterations.
- The last factor in food processing raised by this article is thermal processing, which consists of exposing foods to extremely high and dry heat, in order to increase shelf-life and improve “flavor, color and texture.” This destroys micronutrients and also causes chemical changes in the structure of the food, sometimes causing the production of “health damaging chemicals.” There is some research linking these chemicals to insulin resistance and diabetes, weight gain, and so forth. Data though is sadly lacking, especially when it comes to the effects of this kind of processed food on the gut bacteria.
The article concludes by stating that, “Reviewing recently addressed features of processed foods, it can be concluded that all these factors can in some way be related to obesity, metabolic syndrome and NCD…All considered processing features have been evidenced to affect or disturb the gut microbiota, to a greater or lesser extent. As such, all features induced shifts in microbiota composition.”
But remember – as they also say, “It is obvious that research around the subject of this paper is still in its infancy.” So as I said at the start, much of this is hypothesis or suspect, but not as yet, fact. Still, as you all know, I am all about things you can do now and so…maybe eating a diet that is mainly whole foods is a really good idea?!
[i] Miclotte, L and Van de Wiele, T. Food processing, gut microbiota and the globesity problem. Critical Review in Food Science and Nutrition. 2019. DOI:10.1080/10408398.2019.1596878