The Proof is in the Pudding: How Western diets increase our risk for cognitive decline and Alzheimer’s disease
The food we eat can directly change the way our brain functions. And, depending on what that food is, these changes can be detrimental to our short-term and long-term brain health, even increasing the risk for Alzheimer’s disease, which is a disease characterized by the death of neurons in the brain, leading to impairments in memory and overall cognitive function.
I received my doctoral degree in neuroscience and am currently a postdoctoral researcher at The Ohio State University in the United States. My research focuses on how nutrition impacts the communication between the immune system and the nervous system, and what this means for brain function. More specifically, I look at how different diets impact brain inflammation, learning, and memory in multiple biological models, including ageing and Alzheimer’s disease.
Over the years, this area of research has become more personal for me as I have lost several family members to Alzheimer’s disease and have witnessed how devastating this illness can be, not just for the patient, but also for the caregivers.
I believe the chances of developing Alzheimer’s can be greatly reduced, and in this blog, I will tell you more about it. Understanding the disease is critical for informing medical professionals and, more importantly, the general public, on how to best reduce our risk. Luckily, there is exciting work being done on these topics and this article will discuss one very important factor: diet.
Western Diets and Brain Function
So, what is a “Western diet”?
This is a term that is often used to describe the typical diet consumed in the United States and some countries in Western Europe. This diet is high in saturated fats, added sugar, and simple carbohydrates, and very low in fibre. These foods, such as white bread, pizza, ice cream, and packaged foods, are cheap, tasty, and heavily processed to extend shelf-life and limit trips to the grocery store. Unfortunately, overconsumption of these foods can also lead to metabolic dysfunctions (changes in metabolism that are harmful to the organism) such as type 2 diabetes (insulin resistance), hypertension (high blood pressure), and obesity (high body mass index).
Obesity and metabolic syndrome (a term used to describe some combination of the metabolic dysfunctions mentioned above) are major risk factors for cognitive decline and Alzheimer’s disease later in life. However, several clinical studies have shown that, even in the absence of these other metabolic changes, the single factor of consuming a Western diet (even for a short period!) is associated with cognitive decline and shrinkage of the hippocampus, which is a brain region involved in learning and memory function and Alzheimer’s disease.
Ok, but how can the food I eat, damage my brain?
This is a question that does not have a straightforward answer because it can happen in several different ways. For this article, I am choosing to focus on my area of expertise, which is the immune-to-brain connection.
In pre-clinical research (laboratory research that is before research is done on humans) it has been shown that overconsumption of saturated fats and sugar can increase inflammation in the gut and even impact the function of circulating immune cells. These immune cells can release inflammatory molecules that send signals to the brain that “activate” inflammation in the brain. If this brain inflammation is prolonged, then it can damage neurons and other cells in the brain, which can lead to changes in behaviour or cognitive issues. Besides, there is some evidence, based on magnetic resonance imaging (MRI), that obesity is also associated with brain inflammation in humans. In studies done on humans, research has shown that consuming a Western diet can lead to increased inflammatory molecules in the blood. Again, these inflammatory signals are likely communicated to the brain, resulting in brain inflammation and potential damage to neurons, which can lead to the development of Alzheimer’s disease.
Ageing Increases Vulnerability
I mentioned above that ageing is one of the variables I study regarding nutrition, the brain, and the immune system. This is an important variable because older individuals seem to be more vulnerable to inflammatory triggers (such as an unhealthy diet). This is because aged mammals display chronic, low-grade inflammation, even in the absence of disease. Because of this higher inflammatory level, additional inflammatory stimuli can trigger an even greater, more dangerous inflammatory response.
Is there a solution in sight? Well, there are several things we can do to help lessen the toll that inflammatory stimuli take on our brains.
Potential Tools to Lessen Inflammation
First, we should all try to limit the intake of these inflammatory, processed foods and replace them with healthier options. Just like certain nutrients can be inflammatory, other foods can be anti-inflammatory!
One of the more prominent anti-inflammatory nutrients is omega-3 fatty acids, the main component of fish oil supplements that you can buy at almost any grocery store. They are also abundant in fish such as salmon, cod, and sardines. There is an overwhelming amount of pre-clinical data showing beneficial effects of omega-3s on brain health, including reducing inflammation. There is also some promising data in human clinical studies suggesting omega-3 supplementation can slow cognitive decline in ageing. For more information on how healthy diets can help your brain, you can check out other articles from our blog, here and here.
Other tools can be used to mitigate inflammatory insults and improve the quality of life as we age. These include activities such as a consistent exercise routine and even intermittent fasting, which involves consuming all of your daily calories during an 8–10 hour window so that your body is in a fasted state for 14–16 hours a day. While things like exercise and eating healthy foods is a good idea at any stage in life, the earlier we can start living a healthy lifestyle, the better. There is now evidence from human studies that the earliest brain changes related to cognitive decline and Alzheimer’s disease can be detected during your 40s.
I will close by saying there is no “magic bullet” that will guarantee the prevention of something as complex as Alzheimer’s disease, but there are tools we can employ now to reduce our risk. So I want to ask anyone who reads this to consider how your diet impacts your brain. Whatever this looks like for you if you avoid heavily processed foods and stick to healthy whole foods (like salmon, fruits and vegetables, dark leafy greens, nuts and berries, etc) and get regular exercise, your brain, your immune system, and your future self will thank you.
