Highly processed foods and neuronal health: is there also a link with other neurodegenerative diseases such as multiple sclerosis?
Recently, we reported on “Knowledge stops dementia” about (ultra)processed food, also known as fast food, and the associated risk to neuronal health: Studies have shown that regular consumption of these foods is associated with a significantly higher risk of developing dementia .
Furthermore, there is growing evidence that the quality of diet is closely related to the development or prevention of other diseases, also known as “lifestyle diseases”. For example, the link between excessive consumption of ultra-highly processed foods and the development of cardiovascular disease, obesity, dyslipidemia, and depression is already clear . In a previous study, it was also shown that increasing the amount of highly processed foods in the diet leads to an increase in inflammatory markers in the blood such as C-reactive protein  . For this reason, it is argued that a diet rich in highly processed foods could be a major problem because of its pro-inflammatory effects.
Thus, we have wondered whether there is also evidence in the scientific literature as to whether the consumption of this inflammatory food group could have an impact on the development of the neurodegenerative autoimmune disease multiple sclerosis (MS for short), which focuses on inflammation-related damage to the nerve insulating layer (also known as demyelination or demyelination), which in turn leads to the breakdown of nerve fibers and cells.
Recent studies on the association between MS and nutrition
The relationship between diet quality and the development or progression of MS is still a poorly researched topic. Although the number of published studies has increased in recent years, there is no consensus among researchers on what would be the optimal diet to prevent or treat demyelination and inflammation of the nervous system, the main features of this disease. However, epidemiologic data suggest that individuals who consume more calories, saturated fat, and sugar are at higher risk of developing demyelinating lesions and/or MS. A recent study published in 2022 in the high-impact journal European Journal of Clinical Nutrition has now demonstrated an association between a high intake of ultra-high-processed foods and a higher risk of developing central nervous system demyelinating lesions .
The authors studied a group of participants in the Ausimmune Study (Australian Multi-center Study of Environment and Immune Function)  and used questionnaires to assess the quality of the diets of 282 individuals in the 12 months before diagnosis of initial myelin damage, recording primarily the amount of ultraprocessed foods they consumed The diet of patients diagnosed with demyelinating damage was compared with the diet of individuals without such a diagnosis (control group). Results showed that higher consumption of ultra-high processed foods was significantly associated with a higher risk of being diagnosed with demyelination in the central nervous system for the first time.
Unlike other studies that have assessed disease severity, that is, the progression of damage to the myelin layer after the disease is diagnosed, this study is particularly important because it assesses the risk of developing lesions in patients without a diagnosis or before diagnosis. Considering that many patients change their dietary habits after receiving an MS diagnosis (which could affect the results), this study provides the opportunity to determine the importance of diet in the prevention of initial demyelinating damage , or in other words, with this knowledge, one recognizes the risk of developing a higher risk of demyelinating disease such as MS by consuming ultraprocessed foods.
Furthermore, this study advises against taking extreme measures or radical dietary changes by so-called crash diets. Instead, it is recommended to reduce the risk of demyelination damage by a relatively simple measure: by avoiding highly or ultra-highly processed foods.
Yet what are ultra-highly processed foods anyway?
Ultrahighly processed foods are those that undergo many processing steps, including the addition of chemical ingredients not commonly used in cooking (such as high fructose corn syrup, hydrogenated oils, artificial flavors, and hydrolyzed proteins); they are typically high in energy density and low in nutrients. The processes and ingredients used in the production of ultra-processed foods are designed to be highly cost-effective (low-cost ingredients, long shelf life, highlighted branding), convenient (ready-to-eat), and highly palatable (stimulates taste buds).
Examples of ultra-processed foods include: packaged snacks, candy, baked goods, bulk bread, many breakfast cereals, prepared foods, margarine, processed meats, etc.
The classification most commonly used in scientific studies to determine the degree of processing of foods is the NOVA classification , which categorizes foods as unprocessed/minimally processed, processed, and ultra-highly processed. . The Australian study has shown that the danger lies in the excessive consumption of this last category of food.
Why are ultra-processed foods bad for your brain health?
There are a number of reasons that explain the effect of ultra-processed foods in our bodies and what makes this class of foods so dangerous:
- Ultra processed foods contain large amounts of unfavorable nutrients, such as free or added sugars, bad and excessive fats, and little fiber, with a high energy density. These characteristics may explain the negative effects of these products on cardiovascular and cardiometabolic risk factors and on the risk of overweight/obesity.
- They may contain many harmful compounds formed during food processing, such as acrylamide and acrolein Although these compounds are also formed during food preparation at home (e.g., high temperatures during cooking), they are present in greater amounts in ultrahighly processed foods. Both acrylamide and acrolein are associated with an increased risk of cardiovascular disease and are strong pro-inflammatory agents.
- Hormonally active substances such as bisphenols may also be present in the packaging of ultrahigh-processed foods. Although bisphenol A is banned for use in food packaging in many countries, it has since been replaced by other components such as bisphenol S, which is also endocrine disruptor and is suspected to be absorbed orally even more effectively than bisphenol A. These products can cause hormonal changes that lead to obesity and inflammation.
- Because these preparations are made very palatable, they cause a delayed satiety signal, which can lead to higher overall food intake that causes fat accumulation, obesity, and inflammation.
- They can alter the gut microbiome to disrupt it, leading to dysbiosis and triggering the production of pro-inflammatory cytokines, which in turn can contribute to neuroinflammation and neurodegeneration.
- • They are high in saturated fat and trans fatty acids, which have inflammatory potential and cause oxidative stress, while being low in anti-inflammatory fats such as omega-3 fatty acids.
- The increase in the consumption of ultra-highly processed foods is simultaneously decreasing the consumption of natural or minimally processed foods that provide adequate amounts of macronutrients and are sources of vitamins and minerals important for both immune and nervous system functioning.
The association between diet and multiple sclerosis has been demonstrated in some epidemiological studies. Although no particular type of diet has been shown to prevent or slow disease progression in any case, there is growing evidence that diets rich in ultrahighly processed foods may be associated with the development of inflammatory diseases. A new study from Australia has shown that a higher intake of ultrahighly processed foods was associated with a higher likelihood of first clinical diagnosis of demyelination.
The study clearly showed that radical diets are not necessary for the prevention of MS. Such diets are usually very restrictive, being based on a very reduced and one-sided diet, up to the complete replacement of food with any shakes or supplements. According to the authors of the study, it makes much more sense to identify the class of these highly processed, pro-inflammatory foods and avoid them – either completely or to a large extent – in order to reduce the risk of demyelinating lesions and multiple sclerosis.
Although the aforementioned study  focused on multiple sclerosis, the findings are also important for other neurological diseases. Multiple sclerosis also has a significant neurodegenerative component, whereas dementia is primarily neurodegenerative. In this respect, avoiding ultra-highly processed foods is at least as important with regard to Alzheimer’s and dementia, as recent studies show.
If you would like to learn more about prevention of multiple sclerosis, please feel free to visit our partner project, theLife-SMS.
- ↑ Li H, Yang H, Zhang Y, et al. Association of ultraprocessed food consumption with risk of dementia: A prospective cohort (2022) Neurology September 06; 99 (10)
- ↑ Pagliai G, Dinu M, Madarena MP, Bonaccio M, Iacoviello L, Sofi F. Consumption of ultra-processed foods and health status: a systematic review and meta-analysis. Br J Nutr. 2021 Feb 14;125(3):308-318. doi: 10.1017/S0007114520002688. Epub 2020 Aug 14. PMID: 32792031; PMCID: PMC7844609
- ↑ Lane MM, Lotfaliany M, Forbes M, Loughman A, Rocks T, O’Neil A, Machado P, Jacka FN, Hodge A, Marx W. Higher Ultra-Processed Food Consumption Is Associated with Greater High-Sensitivity C-Reactive Protein Concentration in Adults: Cross-Sectional Results from the Melbourne Collaborative Cohort Study. Nutrients. 2022 Aug 12;14(16):3309. doi: 10.3390/nu14163309. PMID: 36014818; PMCID: PMC9415636.
- ↑1 ↑2 Mannino A, Daly A, Dunlop E, Probst Y, Ponsonby AL, van der Mei IAF; Ausimmune Investigator Group; Black LJ. Higher consumption of ultra-processed foods and increased likelihood of central nervous system demyelination in a case-control study of Australian adults. Eur J Clin Nutr. 2023 Feb 8. doi: 10.1038/s41430-023-01271-1. Epub ahead of print. PMID: 36754977.
- ↑ https://www.msaustralia.org.au/ausimmune/
- ↑ Monteiro CA, Cannon G, Levy RB, Moubarac JC, Louzada ML, Rauber F, Khandpur N, Cediel G, Neri D, Martinez-Steele E, Baraldi LG, Jaime PC. Ultra-processed foods: what they are and how to identify them. Public Health Nutr. 2019 Apr;22(5):936-941. doi: 10.1017/S1368980018003762. Epub 2019 Feb 12. PMID: 30744710.
Picture by Leon Ephraïm on Unsplash