Nutrition as medicine for healthy aging – including the brain

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By Anastasia Dimitropoulou

For the International Day of Older Persons, we wanted to revisit the importance of nutrition in the context of healthy aging.

A study published in JAMA in July 2019 investigated whether a healthy lifestyle is associated with lower risk of dementia regardless of genetic risk. It included adults of European ancestry aged at least 60 years without cognitive impairment or dementia at baseline, and followed them between 2006 to 2016/2017.

The study demonstrated that a favorable lifestyle in participants with high genetic risk was associated with lower dementia risk, whereas participants with high genetic risk and an unfavorable lifestyle had a significantly higher risk for dementia. The conclusion was that genetic factors increase the risk of dementia, but a healthy lifestyle can play a role in minimizing the risk.

The conclusion was that genetic factors increase the risk of dementia, but a healthy lifestyle can play a role in minimizing the risk.

Part of a healthy lifestyle includes nutritional choices.

More and more scientific studies demonstrate that the cause of most diseases involves an interaction between genetics, lifestyle choices, and environmental exposures. Treating these diseases requires an understanding of these interactions and the development of a personalized approach. The role of nutrition in overall health is of major importance both for disease prevention and for healthy aging.

Taking care of our brains in conjunction with our bodies is what leads to healthy aging and a better quality of life. Declining brain health is the fastest-growing epidemic in the world and once it starts, it is almost impossible to reverse.

Today about 50 million people are living with dementia globally; this number is expected to increase to over 65 million by 2030. Even after decades of research, no disease-modifying therapy or validated preventative strategy exists for Alzheimer’s Disease (AD), a progressive age-related neurodegenerative disorder.

However, researchers have recently proposed a potential role for the gut microbiome (the healthy bacteria in our gut) in the initiation and exacerbation of AD. Indeed, AD patients tend to have distinct and less diverse microbiota from control sex- and age-matched individuals, including a greater abundance of pro-inflammatory and less anti-inflammatory bacteria.

A very recent publication also showed that removing the gut microbiome had a profound effect on the amyloid pathology in mouse models of AD, but only in male mice. We do not yet know why and how, but sex differences between the male and female microbiomes could play a role in the disease.

What is the role of the gut microbiome in health and brain health?

The intestinal microbiome consists of about 100 trillion bacteria living in the human gut. They are in a symbiotic relationship with us, their hosts, and their genome outnumbers our genome about 150 times!

These bacteria, known as microbiota, have an impact on our systems via nutrient processing. They affect both the brain physiology and the incidence of disease risk. This is because there is a bidirectional communication between the gut and the brain. Known as the “gut-brain axis”, this connection is now used to explain the tight communication between the gut and brain and the importance of their cross-talk for brain functions in health and disease.

At the same time, the gastrointestinal tract has also its own nervous system, known as the Enteric Nervous System (ENS), commonly referred to as “the second brain”. The ENS has as many nerve cells as the spinal cord and it is in constant communication with our “first” brain, affecting our mood and mental function.

As everything is so interconnected, whatever we eat affects not only our gastrointestinal system, but the nerve cells of the ENS, the normal function of our brain – and even our immune system.

When the composition of the microbiome is changed by increased levels of harmful bacteria, a state of dysbiosis is generated, where the amounts of the beneficial bacteria are reduced. The gut lining is disturbed leading to “leaky gut,” holes in the intestinal lining allowing larger molecules (partially digested food particles) to pass through the gut wall, exposing the gut-associated immune system to a wide variety of substances our immune cells would otherwise not come in contact with.

Recent evidence suggests that gut microbiome dysbiosis may affect the synthesis and secretion of several brain-derived neurotrophic factors which are associated with cognitive decline and dementia, and that modulation of the gut microbiome may induce positive effects on neuronal pathways that can slow down the progression of dementia.

The Mediterranean diet and its role in disease prevention

“Western” dietary patterns high in saturated fat and simple carbohydrates are associated with increased risk of disease, including dementia.

This is in contrast to the “Mediterranean-style” diet which is associated with reduced incidences of several chronic diseases, such as obesity, type-2 diabetes, gastrointestinal cancer and cardiovascular diseases, as well as neurodegenerative diseases.

As a result, in 2013 the Mediterranean diet was added to the “Representative List of the Intangible Cultural Heritage of Humanity” by the United Nations Educational, Scientific and Cultural Organization (UNESCO).

A Mediterranean-style diet is a nutritionally balanced diet, characterized by a high intake and frequency of fiber, extra-virgin olive oil, fruits, nuts, vegetables and cereals and a moderate consumption of “fatty” fish, such as salmon and sardines, poultry, a low intake or absence of dairy products, occasional red meat, and every so often a glass of red wine consumed with meals.

The mechanism of how a Mediterranean diet can affect the gut microbiome and the microbial metabolites is not exactly clear. However, a study published last month explains how the various components of such a diet – including the long-chain omega-3 fatty acids found in fatty fish, extra-virgin olive oil and nuts, the polyphenols in fruits, vegetables, cereals, coffee, tea, cacao and wine as well as the probiotics and vitamins – play a role in the prevention of stroke, age-related cognitive decline, and AD.

What foods contribute to healthy aging?

The rule of thumb is to simply avoid any processed foods and any products with ingredient labels you simply cannot read. Buy fresh (or even frozen), preferably locally-sourced and whole foods.

The World Health Organization (WHO) recommends adopting a plant-based diet, which does not mean being vegetarian or vegan, but having approximately 75% of vegetables and 25% of meat and fish.

Sweeteners that you can use include honey, coconut sugar, and maple syrup amongst others. Use as many herbs and spices (oregano, cumin, turmeric, dill, sea salt, black pepper) as you want to spice up your dishes.

Drinking a lot of filtered, alkaline water and herbal teas (green, white and jasmine) is also fundamental to a healthy lifestyle, not just for older people but for everyone who is aging.

Nutrition alone is not the key to a healthy lifestyle – it goes hand in hand with

  • movement and exercise, including outdoor activities,
  • maintaining and building personal connections, spending time with family and friends,
  • giving to your community and taking time to develop personally, and
  • ensuring a great quality of sleep.

With these pillars of a healthy lifestyle, you increase your chances to keep living well, and feel even better until the end.

 

Photo credit (including featured image): Anastasia Dimitropoulou – all rights reserved; do not reproduce without explicit permission.

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