Updated 22 June 2015

How diet and physical activity affect brain function – Part I

DietDoc discusses the factors that contribute to cognitive decline in seniors and how to delay or stop brain degeneration.


Last week we discussed the revolutionary finding that an increased intake of dairy products (milk, yoghurt, cheese) increases glutathione levels in the human brain and may help to counteract deterioration of our cognitive processes.

Glutathione is a powerful antioxidant which is capable of protecting brain cells against damage inflicted by so-called reactive oxygen species (ROS) and free radicals, thus preventing oxidative stress. Alzheimer’s, Parkinson’s and dementia, among other conditions, have been linked to the negative effects of oxidative stress.

Read: Can glutathione make us live healthier for longer?

Ageing population

Nowadays, humans are living a great deal longer, and the percentage of senior citizens is increasing steadily. Unfortunately with this rise in the number of older people, there has also been an increase in the number of individuals suffering from brain disorders such as Alzheimer’s disease. Researchers are trying to determine which factors contribute to brain damage and are searching for ways to delay or stop brain degeneration.

A particularly valuable summary of research results relating to lifestyle and dietary factors was published by Romain Meeusen of the Department of Human Physiology at the Vrije Universiteit, Brussels, last year.

Lifestyle the key

According to Meeusen, evidence is accumulating that “diet and lifestyle can play an important role in delaying the onset or halting the progression of age-related health disorders and can improve cognitive function".

The most important protective factors appear to be exercise, as well as the foods you do and don’t eat!

Physical activity

Exercise has been linked to a reduction in heart disease, colon and breast cancer, obesity, Alzheimer’s disease, depression and anxiety. Most people may be surprised to hear that that they can increase their brain power by exercising on a regular basis.

The process starts at a young age. Currently more and more young children are becoming increasingly sedentary and unfit, which leads to childhood onset of lifestyle diseases, such as cardiovascular disease, type 2 diabetes and obesity. More recent research has also identified a link between obesity in children and teenagers and poor academic performance.

Read: Obesity and diseases

There was probably never a worse decision by educational authorities than to remove physical education a part of the curriculum in schools. Although financial constraints may prevent the majority of schools from having adequate sports facilities, where there is a will, there is a way.

There is little doubt that the time spent doing physical activity at schools would pay dividends in terms of improved mental performance.

As far as the older generation is concerned, there is never a time when people are too old to be physically active. Don’t huddle in front of your TV, PC or tablet – go for a walk, even if it’s only around the block or to the corner café.

Dietary factors that prevent brain deterioration

a) Foods to avoid

Based on research results, Meeusen lists the following foods and diets as detrimental to healthy cognitive function:

- Typical Western diets rich in sugar, refined carbohydrates, saturated fats, trans fats and an excess of energy (kilojoules). Such diets increase oxidative stress and reduce the plasticity of the synapses (connections between nerves), as well as brain function.

- Skipping breakfast reduces brain function, while eating breakfast helps to improve mental ability in schoolchildren and adults of all ages. A study with children between the ages of eight and 11 years compared their ability to solve numerical problems after an overnight fast, and again after eating or skipping breakfast.

The children who ate breakfast did significantly better when it came to solving simple addition problems than the children who continued to fast. It is a sobering thought that so many of our schoolchildren in this country do not eat breakfast because of poverty and are reliant on a school meal to fuel their brain processes. 

- Foods that are contaminated with high levels of lead, iron, aluminium and zinc have been linked to the development of Alzheimer’s disease. It is important to differentiate between foods that provide nutrients such as iron and zinc in adequate quantities for healthy brain function and foods that have been contaminated with these metals to such high levels that they cause damage.

The recent withdrawal in India of instant noodles with harmful levels of lead is an example of action to prevent exposure to unacceptable lead levels in foods that are popular among young children and the population in general.

b) Foods that can improve brain function

As researchers delve into dietary factors that can possibly improve cognitive function, a variety of foods have been identified that have a beneficial effect, such as omega fatty acids, polyphenols, flavonoids, branch-chain amino acids, tyrosine, certain carbohydrates, dairy products and caffeine.

Because foods together with physical activity can potentially determine how well our brains function, we shall have an in-depth look at the above mentioned nutrients in Part 2 of this series on how to keep our brains healthy and possibly prevent cognitive decline.

Read more:

Milk can boost your brain power

Healthy eating key to healthy lifestyle

What are the health benefits of exercise?


- Mahan K L et al (2012). Krause’s Food & the Nutrition Care Process. Elsevier Publishers, USA.

- Meeusen R (2014). Exercise, nutrition and the brain. Sports Medicine:44, (Suppl 1): S47-S56.

- Reuters (2015). Maggi withdraws all noodles in India after state bans and lead scare. The Guardian.

Image: Human brain from Shutterstock    

Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Read more of her articles.


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