The Gut Microbiome in Alzheimer’s disease

Our gut provides a home for tens of thousands of bacteria. They play a crucial role in maintaining homeostasis (or physical equilibrium) which is important because any alterations to homeostasis could lead to the onset and progression of diseases.
We know that in Alzheimer’s disease there tends to be an imbalance in gut bacteria. There are less beneficial bacteria and there are lower numbers overall.

We don’t know if having an imbalance (dysbiosis) of the gut bacteria is one of the causes of Alzheimer’s disease or if it a consequence. We do know that by making improvements to the balance of bacteria in Alzheimer’s disease, there is the potential to;
- make the brain more adaptable to change
- that it could lead to changes in brain pathology
- and that symptoms could be improved
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Neuroinflammation
Some of the less beneficial bacteria that are abundant in the gut of someone with Alzheimer’s can be pro-inflammatory. This could be through the production of lipopolysaccharides (which induce inflammation) by some bacteria.2

Beneficial bacteria make beneficial things for us including producing short-chain fatty acids that help to nourish the lining of the gut. Without this nourishment, and in the presence of pro-inflammatory bacteria and lipopolysaccharides, it’s possible for the gut lining to become compromised and allow particles through. This leaky gut could be one of the causes of the brain becoming inflamed in Alzheimer’s.

A Wholefoods Approach to a Healthy Microbiome
Our diet can positively and negatively influence the microbiome. Fatty foods tend to increase the abundance of inflammatory bacteria. Eating a sugary diet has been shown to lead to pathogenic and pro-inflammatory bacteria and a reduced diversity. A diet high in protein can lead to undigested protein ending up in the large part of the gut. The bacteria that ferment the protein are encouraged to grow which leads to an abundance of protein fermenting and pro-inflammatory bacteria.

Tips for a healthy microbiome

- Limit fatty foods containing trans fats and saturated fats. These include processed foods, cakes and biscuits.
- Eat foods rich in omega-3 fatty acids such as walnuts, hemp, chia, and flaxseeds and oily fish such as salmon, mackerel, and sardines.
- Eat fermented foods such as kimchi, yogurt, sauerkraut and kefir. These have been proven to improve cognition. (1)
- Eat foods rich in monounsaturated fatty acids such as olive oil, nuts, and seeds.
- Include coconut oil in your diet which contains medium-chain triglycerides which are anti-microbial to gut microbes.
- Eat plenty of vegetables and fruits as it helps to promote bacteria that ferment the fibre and leads to microbial richness. (1)  Foods high in fibre - such as vegetables and wholegrains promote a healthy ratio of beneficial bacteria. (1)
- Eat foods that contain curcumin. The richest source of curcumin is turmeric. Curcumin favours beneficial bacteria.
- Eat a wide variety of coloured fruits and vegetables because they contain polyphenols that promote beneficial bacteria.
- If your struggling to eat a wide variety of fruits, vegetables, pulses, and grains, consider a supplement containing a blend of bifidobacteria and lactobacilli. Studies conducted so far have been poorly designed and more quality studies need to be conducted. Overall, the studies support the use of supplements for improving cognition. (2)

Diagram reference: Toribio-Mateas, M., 2018. Harnessing the Power of Microbiome Assessment Tools as Part of Neuroprotective Nutrition and Lifestyle Medicine Interventions. Microorganisms, 6(2), p.35.

(1) Frausto, D., Forsyth, C., Keshavarzian, A. and Voigt, R., 2021. Dietary Regulation of Gut-Brain Axis in Alzheimer’s Disease: Importance of Microbiota Metabolites. Frontiers in Neuroscience, 15.

(2) Ticinesi, A., Mancabelli, L., Carnevali, L., Nouvenne, A., Meschi, T., Del Rio, D., Ventura, M., Sgoifo, A. and Angelino, D., 2022. Interaction Between Diet and Microbiota in the Pathophysiology of Alzheimer’s Disease: Focus on Polyphenols and Dietary Fibers. Journal of Alzheimer's Disease, pp.1-22.

Folate is essential for making new cells, healthy red blood cells, and healthy nerves.
🥕A folate deficiency is rarely alone without other deficiencies so a full vitamin and mineral screening blood test is a good idea.
🌶A folate deficiency could indicate that there is a problem with absorbing the vitamin from the gut. Undiagnosed coeliac disease could be a cause. Inflammatory bowel diseases such as Crohn's disease can also affect absorption.
🥦Taking certain medications can affect folate absorption. These include antiepileptic drugs and sulfasalazine. Furosemide also decreases intestinal folate absorption.
🥬Alcohol can affect folate absorption. As little as two glasses of wine a day can impact hepatic uptake and lead to folate being excreted in the urine.
🌽MTHFR methylenetetrahydrafolate–1 in 10 white British will have the MTHFR genetic polymorphism. This means the reductase enzyme needed for the conversion of folate to its active form is less active.  Not eating a variety of foods could also contribute to a low folate.

If a folate blood test, full vitamin, and mineral test, coeliac test, or a test to see if you have the MTHFR gene are of interest to you, contact me via my website. I offer a full phlebotomy, specimen packaging, and test interpretation package.

BTS of the memory clinic

I often have older adults come into the memory clinic who are not concerned about their memory but their GP had some concerns. 

One client who was not concerned showed some memory loss with a score of 71/100 on the Addenbrooke’s cognitive test. They were unable to recall three words after a delay. They incorrectly copied two intersecting pentagons and a 3D cube. They were unable to tell me the date and the day correctly.

This patient has no concerns with cooking, cleaning, or gardening.  

They had a CT brain scan booked so will come back once the scan is done to see one of our doctors.

It might be that this patient is in the early stages of Alzheimer’s disease but without there also being an impact upon her daily life it is not dementia. It might be that her high IQ helped to delay the onset of memory difficulties.

Exercise is so important for a healthy brain.

Helps to deliver oxygen and nutrients to the brain

Encourages a healthy microbiome

Supports the growth and repair of brain cells

Aids in depression prevention

Aids sleep


Read more

We’ve all heard the phrase ‘use it or lose it’. Here’s some evidence that supports that this may be true in the development of Alzheimer’s disease.

A common comment by patients to the memory clinic, is that their memory is impaired because they haven’t been doing anything or talking to anyone. Lockdown in particular saw some people’s memory declined faster than it may have done. Why did the pandemic lead to a worsening of their memories? Read more

One of the possible mechanisms contributing to the development of Alzheimer’s disease is gut dysbiosis. Gut dysbiosis is where the intestinal flora or bacteria living in the large intestines are unbalanced. Amino acids produced by less beneficial bacteria can trigger an inflammatory response leading to neuroinflammation.
New drug therapies have been developed and are being trialed that remodel the microbiome. Reducing these amino acids may reduce the infiltration of immune cells to the brain, and in turn reduce neuroinflammation. Read more