Nutrition-Cognition: How our food choices affect our brain

Emma Brown | 31 Jan, 2014

We've all heard the expression 'you are what you eat' – but how much should we really be taking notice of what we put into our bodies, and how it might affect us in later life?

It came as no real surprise to me to read in Women's Health magazine this month that research has found a direct link between diet quality and damage to our brains – the brain is, after all, a living organ constantly changing and developing. The latest buzz phrase is 'nutrition cognition'. If we don't look after our diet, what does that mean for our brain health?

What's the science?

The brain is a clever organ that is very choosy about the nutrients that it uses – in fact the only source of energy it can use is glucose (the simplest form of sugar) – so this is one of the main reasons why we need some carbs in our diets. At the same time, the cells of the brain are finely tuned with other nutrients in the diet such as the type of fat we eat, and certain vitamins, minerals and antioxidants.

What seems to be the problem is that people who have a diet that is high in simple sugars, refined carbohydrates and saturated fats may cause permanent damage to their brains by messing around with the insulin in the brain.

Insulin is best known as a hormone made in the pancreas that helps with blood sugar control, and that is affected when someone has diabetes. But now it looks like insulin may also be produced in the brain, acting as a neurotransmitter, passing signals in the brain and helping with memory, tasks and learning behaviours. In the same way that people can become insulin-resistant in the pancreas, this may also be happening in the brain. A diet that is overly rich in sugar and saturated fat may be leading to insulin-resistance in the brain causing short term issues with memory and eventually causing long term, and permanent, damage.

Animal studies have found a link between a high fat/ high sugar diet, disrupted insulin mechanisms and plaques forming in the brain, similar to that seen in Alzheimer's patients. According to the researchers, this phenomenon could help to explain why people with Type 2 diabetes are significantly more likely to go on and develop Alzheimer's. Obviously these studies are in animals so we have to look at the results cautiously, but it makes a lot of sense that a long term unhealthy diet, being overweight and potentially having Type 2 Diabetes could all have an effect on our cognitive health too.

What can we do to reverse this trend?

Well the good news for people with type 2 diabetes, losing weight can improve and even reverse the condition. What we don't know for sure is the impact of this on brain health, but it stands to reason that similar results would be seen.

But what else can we do to improve our chances of a healthy brain?

Again good news. There is quite a bit of evidence in human studies to highlight how a 'brain friendly' diet can help to reduce the risks of developing things like depression and cognitive impairment. One such study in over 17,000 people showed how eating a Mediterranean Diet – rich in oily fish, vegetable oils, fruit and veg – reduced the risk of becoming cognitively impaired. Olive oil in particular is thought to contain a substance that may directly work to prevent the development of Alzheimer's. Omega 3, the essential fat found in oily fish, has also been found to have a positive effect on brain health.

And it's not just about food – being physically active reduced the risk of developing Alzheimer's by over 40% in a study in Canada. A combination of improvements in weight and insulin resistance appeared to help the brain to function more effectively.

The Bottom Line

Although some of the results from the studies I've talked through are pretty compelling, really this isn't new news to us. Following a healthy diet and lifestyle reaps its rewards in so many ways – improvements in cardiovascular health, reduction of risk of diabetes, having more energy... and now improvements in brain function and reduced risk of conditions such as Alzheimer's.

This is a new area of research in humans but it certainly won't be going away anytime soon, so if you want to improve your brain health take some steps towards becoming healthier today. If you're putting off making changes to your life don't delay – your health is too important to wait!

Nutritionist Emma Brown, MSc Human Nutrition is passionate about how food science applies to the human body, and how the nutrients in what we eat affect us and ultimately have an impact on our health.