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Evidence that the gut microbiome and Alzheimer’s are connected is mounting.
Researchers in Ireland, England, and Italy have recently reported that ‘Alzheimer’s symptoms can be transferred to a healthy young organism via the gut microbiota, confirming a causal role of gut microbiota in Alzheimer’s disease.
This data is quite valuable, because it confirms what we have suspected for a long time—the bidirectional communication between the gut and the brain when it comes to Alzheimer’s disease.
Leading up to this report, in a 2022 study, researchers from King’s College in London analysed the blood and stool samples of sixty-eight people with Alzheimer’s disease (AD) and sixty-eight people who showed no signs of dementia.
The ‘Alzheimer’s gut’ was distinct, with an increase in the number of inflammation markers.
This follows up on findings that the gut microbiomes of people with preclinical AD (indicated by altered brain amyloid and tau proteins) had a different composition from those of healthy individuals.
Other recent research has shown that rats implanted with stools from people with Alzheimer’s did not grow as many nerve cells as rats in the control group.
And early trials are beginning to suggest that treating brain stem cells with blood from Alzheimer’s patients can disrupt nerve cell growth, leading researchers to conclude that inflammation in the bloodstream associated with gut metabolites can affect the brain.
There are many different types of dementia, of which Alzheimer’s disease is the most common
All of this is to say that when it comes to Alzheimer’s disease, the research on the gut-brain axis is evolving rapidly, but in my opinion there is one thing about which there is no doubt: there is a definite connection.
From India to Italy: reversing inflammation with nutrition
This connection is something I have suspected for quite some time.
In my practice I have seen many patients with Alzheimer’s who have eaten the standard Western diet for their entire lives and have fallen victim to this disease.
If we look around the globe at other cultures with different diets and compare incidences of Alzheimer’s, we begin to see a correlation.
Take India, for instance. Until recently, when the Western diet became more prevalent, India was cited as having one of the lowest rates of Alzheimer’s in the world.
In northern India, fewer than 1 percent of those over the age of fifty-five had Alzheimer’s—far below the worldwide and US averages.
Though India does not excel in high blood pressure control or diabetes control, most Indians regularly cook with turmeric, a well-known anti-inflammatory agent.
Turmeric is a fantastic anti-inflammatory and is a very versatile ingredient
As discussed earlier, turmeric is a potent anti-inflammatory agent. A great tool for achieving gut health, it has been used for centuries in Asia and is now popular worldwide.
The active ingredient in turmeric is gut-friendly curcumin, which has been shown to improve intestinal barrier function and combat intestinal permeability (leaky gut).
Turmeric also works with the gut microbiome to decrease inflammation, which is what makes it well suited to help in the fight against diseases such as Alzheimer’s.
When I recommended turmeric to [my patients], at first they can be apprehensive, but eventually discover it is quite easy to incorporate turmeric into his diet.
Turmeric does not significantly change the taste of the food and is caffeine free, low in calories, and rich in nutrients. It can be mixed into your favourite drinks, including tea, cocoa, and smoothies.
I add it to scrambled eggs, lentils, and veggies. Turmeric is absorbed well when taken with food, especially foods containing fat and with a dash of black pepper.
Although turmeric is a fantastic addition, changing one thing about a diet is not enough, so it is important to consider a lifelong way of eating that can help reduce inflammation and decrease brain atrophy.
The Mediterranean diet
The Mediterranean diet has been shown to be effective in decreasing inflammation
When it comes to Alzheimer’s disease and helping the microbiome thrive, I tend to recommend the Mediterranean diet to my patients because it has been shown to be effective in decreasing inflammation, which is so important in general and especially when it comes to neurodegenerative disease.
This accessible diet, which is easy for patients to adopt, is based on traditional foods consumed by European cultures around the Mediterranean – particularly in Greece and Italy – and is marked by being low in saturated fat and higher in vegetable oils.
Although exact definitions vary, they all include guidelines for consumption of extra-virgin (cold-pressed) olive oil, vegetables including leafy greens, fruits, whole grains, nuts, and beans/legumes (pulses).
There is moderate to low consumption of fish and other meat, cheese, yogurt, and red wine, and low intakes of eggs and sweets.
To this I add herbs and spices and recommend that red meat be eaten only rarely if at all.
I emphasise that patients (whether they have Alzheimer’s or not) should avoid eating processed meat or any highly processed food, refined grains and oils, foods with added sugars, and beverages sweetened with sugar.
As they make the transition to my interpretation of the Mediterranean diet, I encourage patients to begin by making it a point to eat:
• Beans
• Fibre-rich foods or a supplement like psyllium husks
• Fruits
• Legumes (pulses)
• Nuts and seeds
• Oily fish, in moderation
• Olives and olive oil
• Probiotic and prebiotic foods like yogurt and bananas
• Some spices, such as ginger and turmeric
• Vegetables, especially leafy greens
Simultaneously, I encourage them to avoid:
• Alcohol
• Foods with excessive amounts of sugar or salt
• Hydrogenated palm or coconut oils
• Pre-made desserts
• Processed foods
Along with this, depending on the patient’s palate, I recommend they add in other anti-inflammatory foods, especially:
• Avocados
• Organic berries, cherries, and grapes
• Broccoli
• Fermented foods
• Green tea
• Mushrooms
• And, of course, turmeric
Heal Your Gut, Save Your Brain by Dr Partha Nandi is published by Short Books (RRP £18.99)
