I know you want me to write about COVID-19 vaccines, but a new study seems to show a link between inflammatory foods and dementia. And I thought it might be of interest to my readers.
I’m not a big fan of nutrition studies for reasons that I’ll explain – they are generally hard to interpret, but this one might show us that foods with a higher inflammatory potential are tied to an increased risk of dementia.
Let’s take a look at what was the researchers found.
First, what are inflammatory foods?
Some evidence has suggested that certain foods, nutrients, and non-nutrient food components can modulate inflammatory status acutely and chronically. An earlier prospective study in women seemed to show a link between the inflammatory potential of foods and cognitive decline.
Foods and nutrients associated with the inflammatory biomarkers, such as interleukin (IL)-1β, IL-4, IL-6, L-10, tumor necrosis factor (TNF)-α (which cannot be found in bananas, in case you were wondering), and C-reactive protein, were assigned a value and tallied to obtain a diet inflammatory index score. Higher dietary inflammatory index scores indicated a more inflammatory diet.
An anti-inflammatory diet usually contains multiple daily servings of fruits, vegetables, and coffee or tea (surprisingly), along with frequent servings of legumes. Diets that have less frequent servings of these foods and higher animal fats are considered inflammatory diets.
Inflammatory foods and dementia – the paper
In a paper published in Neurology on 10 November 2021, researchersanalyzed data from 1,059 older adults in the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD), a population-based study that investigates associations between nutrition and age-related cognition in Greece.
Participants had a mean baseline age of 73.1, a mean of 8.2 years of education, and 40.3% were men. Dietary intake was evaluated through a semi-quantitative food frequency questionnaire validated for the Greek population and administered by a trained dietitian.
The researchers found:
- Each unit increase in the dietary inflammatory index scores was associated with a 21% increased risk of dementia over three years.
- Compared to the participants with the lowest inflammmatory diet (highest anti-inflammatory) scores, those with the highest inflammatory index scores were 3X more likely to develop dementia.
- People in the first tertile had the lowest inflammatory index scores with a weekly diet that averaged about 20 servings of fruit, 19 servings of vegetables, four servings of legumes, and 11 servings of coffee or tea.
- People in the third tertile had the highest inflmmatory index scores had a weekly average of nine servings of fruit, 10 vegetables, two legumes, and nine coffee or tea.
Although this study may have shown a decrease in the risk of dementia that is linked to the inflammatory score for the diet, these types of studies must be evaluated carefully. There are several points to be considered:
- The food frequency questionnaires are often subject to measurement errors and bias. A lot of nutritional based studies rely upon the participant’s memory or a diary to ascertain the inflammatory index scores. For example, a participant may misremember what they ate, or, in an attempt to show that they are eating appropriate foods, exaggerate what they consumed.
- Many dietary components, especially spices and herbs, were not included in the study. Now, I don’t believe that spices and herbs have a major impact on health, but we don’t know from this study.
- The researchers did not test for serum levels of inflammatory biomarkers which should change with an inflammatory diet.
The old feathered dinosaur’s take
I find this type of research to be intriguing, but not necessarily conclusive. Can we tell if a diet low in inflammatory foods lowers the risk of dementia?
The problem is that it’s almost impossible to answer this question with a gold-standard, randomized, double-blinded clinical trial. I can’t think of a way to hide, to either the patient or the researcher, whether the participant is getting 20 servings of fruit or just 5 servings. It will be pretty obvious to everyone.
That being said, despite my being a full-fledged carnivore, I’m going to have to consider upping my consumption of fruits, vegetables, and legumes. I’m good at coffee and tea.
Although I remain skeptical about these types of diet studies, there are enough of them out there that maybe we should take notice of them. And there are other benefits of 20 servings of fruit and 20 servings of vegetables – maintaining weight is one of the important ones.
I am not fully convinced that an anti-inflammatory diet is a guaranteed method to prevent dementia, but the benefits, even if small, far outweigh the risks. Unless you hate fruits and vegetables.
- Charisis S, Ntanasi E, Yannakoulia M, Anastasiou CA, Kosmidis MH, Dardiotis E, Gargalionis AN, Patas K, Chatzipanagiotou S, Mourtzinos I, Tzima K, Hadjigeorgiou G, Sakka P, Kapogiannis D, Scarmeas N. Diet Inflammatory Index and Dementia Incidence: A Population-Based Study. Neurology. 2021 Nov 10:10.1212/WNL.0000000000012973. doi: 10.1212/WNL.0000000000012973. Epub ahead of print. PMID: 34759053.
- Dardiotis E, Kosmidis MH, Yannakoulia M, Hadjigeorgiou GM, Scarmeas N. The Hellenic Longitudinal Investigation of Aging and Diet (HELIAD): rationale, study design, and cohort description. Neuroepidemiology. 2014;43(1):9-14. doi: 10.1159/000362723. Epub 2014 Jul 2. PMID: 24993387.
- Hayden KM, Beavers DP, Steck SE, Hebert JR, Tabung FK, Shivappa N, Casanova R, Manson JE, Padula CB, Salmoirago-Blotcher E, Snetselaar LG, Zaslavsky O, Rapp SR. The association between an inflammatory diet and global cognitive function and incident dementia in older women: The Women’s Health Initiative Memory Study. Alzheimers Dement. 2017 Nov;13(11):1187-1196. doi: 10.1016/j.jalz.2017.04.004. Epub 2017 May 19. PMID: 28531379; PMCID: PMC5909961.
- Shivappa N, Steck SE, Hurley TG, Hussey JR, Hébert JR. Designing and developing a literature-derived, population-based dietary inflammatory index. Public Health Nutr. 2014 Aug;17(8):1689-96. doi: 10.1017/S1368980013002115. Epub 2013 Aug 14. PMID: 23941862; PMCID: PMC3925198.
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