- In Greece, researchers have looked at the link between inflammatory diets and the incidence of dementia in the elderly.
- They discovered that those who ate highly inflammatory diets were three times more likely than those who ate anti-inflammatory diets to acquire dementia.
- Because the study was observational, the researchers stress that a direct association between inflammatory diets and dementia risk cannot be established.
According to the United Nations, the global population of people aged 60 and over will increase from 962 million in 2017 to 2.1 billion in 2050. Experts predict that as the population ages, dementia rates will rise.
People’s immune systems encounter a sort of persistent low-grade inflammation as they get older. This type of age-related inflammation has been linked to dementia and cognitive impairment by experts.
Different diets, according to research, can affect inflammation rates both acutely and chronically.
The following foods have been related to high levels of inflammation:
- unhealthy oils
- excess amounts of red meat
The following foods are known for their anti-inflammatory properties:
- nuts and seeds
- legumes, such as lentils
It may be possible for physicians to prescribe dietary therapies for cognitive health if they can quantify the inflammatory potential of various diets.
However, little study has been done on the consequences of an inflammatory diet on cognitive health until recently. Although some studies have established a correlation between higher inflammatory food intake and poor cognitive capacity and memory, others have found no such link.
In addition, the only prospective population-based study that has looked into the issue thus far has only involved women. This restricts the applicability of the findings.
Researchers from the United States, Greece, and Ireland recently conducted a population-based investigation on the impact of inflammatory diets on cognitive impairment in men and women.
Dr. Nikolaos Scarmeas, Ph.D., of the National and Kapodistrian University of Athens in Greece, stated, “There may be some potent nutritional tools in your home to help fight the inflammation that could contribute to brain aging,” Dr. Scarmeas is a member of the American Academy of Neurology and a Fellow of the American Academy of Neurology.
“Diet is a lifestyle component that you can change, and it may help to prevent inflammation, which is one of the molecular processes linked to the risk of dementia and cognitive impairment later in life.”
“There has been previous conflicting literature on associations between inflammatory aspects of diet and cognition. Our study adds to the scientific argument favoring a potentially important role of inflammation,” he told Medical News Today.
The research was published in the journal Neurology.
Diet and aging
Individuals were chosen from the Hellenic Longitudinal Investigation of Aging and Diet, a population-based study that follows the epidemiology of dementia and other neuropsychiatric disorders in the aging Greek population.
The participants in this study are evaluated every three years by the researchers. So far, each participant has received two evaluations.
The researchers looked at a total of 1,059 people for their study. At the time of the initial examination, none of the participants had dementia, and they all supplied dietary information on the key food types they had consumed in the previous month.
The Dietary Inflammatory Index (DII), a technique that may assess a person’s diet’s inflammatory potential, was used to examine the diets of the participants. There are 45 dietary factors in all, including macronutrients and micronutrients, bioactive substances, and spices.
Based on how inflammatory their diets were, the subjects were placed into three equal groups:
- The first group, which had the least inflammatory diets, had DII scores ranging from -5.83 to -1.76.
- The second group had DII scores of between -1.76 and 0.21.
- The third group, which had the most inflammatory diets, had scores of between 0.21 and 6.01.
Those with the greatest anti-inflammatory diets ingested on average the following items each week:
- 20 servings of fruit
- 19 servings of vegetables
- 4 servings of beans and other legumes
- 11 servings of coffee or tea
Meanwhile, those with the most inflammatory diets consumed an average of:
- 9 fruit servings per week
- 10 vegetable servings per week
- 2 legume servings per week
- 9 coffee and tea servings per week
During the three-year follow-up period, 62 of the 1,059 people the researchers looked at got dementia.
The researchers discovered that those who ate the most inflammatory diets were 3.43 times more likely to acquire dementia than those who ate the least inflammatory diets.
They also discovered that each 1-point rise in DII score was associated with a 21% increased risk of dementia.
The researchers explain the findings by stating that the immune system begins to deteriorate around the age of 40.
Inflammaging occurs when the immune system produces more pro-inflammatory mediators, which can reach the central nervous system and lower levels of brain-derived neurotrophic factor (BDNF). BDNF is a protein that helps neurons develop, mature, and maintain their health.
Oxidative stress and the development of apoptosis, or programmed cell death, are also associated to inflammation. According to the researchers, these effects are part of some of the most important neuroinflammatory and neurodegenerative processes implicated in dementia.
Despite the fact that inflammation is a frequent symptom of aging, research reveals that some foods may increase it.
Prof. Con Stough, a professor of cognitive neuroscience at Swinburne University in Australia, explained to MNT what he believes is the source of the association between inflammatory diets and dementia:
“If you rule out a non-causative explanation, i.e., that people with dementia or who are already at risk [of] dementia show behaviors [that] exacerbate their poor diets (e.g., not cooking nutritional foods, eating out at fast food places more often, etc.) then there could be many mechanisms. Many of these we simply don’t really understand.”
Prof. Stough was not a part of the new research.
“Certainly, the microbiome has the potential to have a significant influence.” What we consume appears to have an influence on the variety of our microbiome, or the microorganisms that reside in it. Gut bacteria appear to have a role in inflammation, producing peptides that can exacerbate inflammation (bad bacteria).”
“As we get older, too, there is greater leakage from the gut [that] also causes inflammation, so having a bad diet could increase the number of pro-inflammatory bacteria in the gut,” he added.
“Different meals can also raise pro-inflammatory cytokine levels. […] Increased inflammation, also known as systemic inflammation, can harm neurons and have a negative influence on cardiovascular function. Prof. Stough noted that “both direct brain damage and changes in cardiovascular function might contribute to cognitive decline and raise dementia risk.”
More inflammatory diets are positively connected to a risk of dementia in community-dwelling older persons without a history of cognitive impairment, according to the study.
The study’s advantages and disadvantages
The results of the latest study may be distorted due to the fact that 689 of the participants did not show up for follow-up exams. Individuals in good cognitive health may have been more prone to miss a subsequent evaluation because they did not see the necessity for it.
“Based on the findings of this study, it appears that if a section of the community adopts anti-inflammatory eating habits, future dementia cases may be reduced,” Dr. Scarmeas told MNT.
“However, it’s worth noting that this was an observational research rather than a clinical trial.” It was also for a brief period of time, barely three years. As a result, it simply indicates a connection, not proof, that consuming an anti-inflammatory diet decreases brain aging and dementia.”
The researchers also point out that the epidemiological nature of their study means they can’t prove causality, and that the three-year follow-up period may not accurately reflect the long-term effects of inflammatory diets.
“The study has both merits and disadvantages,” Dr. Stough explained.
“First and foremost, it’s an epidemiological research, which means it’s an observational study. It asks questions at several periods in time to see if changes in diet at one point in time [predict] dementia risk at another point in time. It is well-constructed in terms of epidemiological studies, but one of the issues with this sort of study is that [the researchers] may have overlooked some crucial component that may explain the findings.”
“For instance, they didn’t measure the amount of exercise or cognitive training each participant [had] been doing over that period of time. Could those variables also predict diet quality? They both could potentially account for the reported relationships between diet and dementia risk. There could be many others,” he continued.
“It also doesn’t connect the dots, so it assumes that certain foods are related to an increase in certain pro-inflammatory cytokines, such as Il-6. While I think there is great logic in doing this, as there have been previous studies standardizing this approach, it is still an assumption.”
“The other issue is that this study doesn’t really offer the mechanisms by which diet and inflammation degrade cognition in this sample,” he explained.
Dr. Stough responded to MNT’s question on how these discoveries could affect public health:
“We need to have a serious look at pro-inflammatory foods that we consume in Western diets. There has recently been a lot of attention paid to research on Mediterranean diets, which are anti-inflammatory and seem to have positive effects against cognitive decline and dementia risk.”
”Diets that comprise takeaway foods and fast foods are generally leading to pro-inflammatory diets,” added Dr. Stough. ”We need to consider healthier diets that focus on vegetables and fruits, in general, whole foods, etc. Given that we are all busy, this will not be an easy goal to achieve, but we need to find ways to promote healthier diets.”
”Certainly, studies like this offer us a huge opportunity to explain to the community the potential long-term damage of pro-inflammatory diets,” he concluded.