FOOD FOR THOUGHT:
We pretty much all accept what we choose to eat and drink affects our health. Much attention has been given to the factors that influence heart, gut and liver health. Yet we really don’t talk about how food and lifestyle choices affect brain health.
We’re aware the brain doesn’t always work so well as we get older. In fact, for the over 50s, concerns about dementia and “losing one’s marbles” have now overtaken those of cancer or heart disease. The good news is that while you can’t change the genes inherited from your parents, nor many aspects of the environment around you, you can change your diet and your lifestyle.
The march of time is unstoppable and ageing is inevitable. Yet some people age more slowly than others. If we understand why, we can implement the strategies that will help us put the brakes on the ageing process, and that includes the ageing of the brain.
Scientific studies have illuminated many factors that count when it comes to looking after your brain. Your brain needs the right nutrients and hydration to work at its best. Keeping good eating and lifestyle habits over the years will help slow the ageing process of the brain, helping it work better as you age.
There are factors we know to be important for human health, but what wasn’t appreciated and understood until relatively recently was the impact these things had on the brain. For example, we used to think dementia was just the luck of the draw, but we now know the risk can be substantially reduced through following a healthy eating pattern, such as a Mediterranean-style diet.
Pay attention to these things and you’ll reap the benefits. Each impacts on the others, so by giving credence to each you improve them all – when you exercise you feel more like eating healthy food; when you’re sleeping well you are more inclined to exercise. When your stress is at a manageable level you’ll find you sleep better and so on.
The ageing brain
Age affects every cell in the body. Visibly, we see the effects on skin, hair and body composition (muscle and fat levels), but ageing is also responsible for changes in the brain.
Generally with age, most of us find we’re less able to quickly retrieve information, such as remembering names, and we’re not as adept at learning new things. Others will succumb to more serious and debilitating forms of dementia. However, the news isn’t all bad.
Many people in the later decades of their lives can score just as well as younger people on cognitive tests, even those who are later shown to have the same degenerative changes to their brain that those with dementia exhibit. Such discoveries led to the concept of cognitive reserve. Cognitive reserve is your brain’s ability to adapt and form new ways of working when certain connections or parts of the brain become damaged.
Think of this scenario. If you had to drive from A to B and discovered that your usual route was closed due to roadworks, you would try to find an alternative route. This is essentially what your brain has the power to do. With the right stimulus and
“You can’t change genes inherited from parents, but you can change diet and lifestyle.”
environment it can form new “routes”. The ability to do this is your cognitive reserve, and there is much you can do to build and sustain it.
Eating more vegies
This seems to be one of the most positive steps you can take to help keep your brain healthy. A review of nine different studies with over 44,000 people found that the more vegies people ate, the lower their risk of dementia and the slower their rate of cognitive decline. One of those studies found that the strongest association was with green leafy vegetables. Women eating the most leafy greens compared to those eating the least had a significantly lower decline in their cognitive abilities, equivalent to measuring one to two years younger.
Leafy greens are also some of our best sources of protective antioxidants, including carotenoids and flavonoids, as well as vitamin C, which are also related to a lower risk of dementia and cognitive decline. One thing of importance – carotenoids are fat-soluble and therefore to absorb them you must have some fat along with your vegies. That’s why teaming vegies with extra virgin olive oil, Mediterranean-style, is so good for you, not to mention delicious!
Glucose, the premium fuel for the brain
The role of carbohydrates is important, they supply the glucose (energy) needed by the brain and other organs to function properly. The brain is a glucose-greedy organ, and it’s the organ that uses more energy than any other in the body. An adult brain uses on average around 120g of glucose a day, that equates to roughly 20 per cent of the total energy used by the entire body.
The brain cannot store glucose, so it needs a constant supply from the bloodstream, but to maintain balanced blood sugar levels it all comes down to what we eat, when, how much we eat and how we move. Eating too many highly refined carbohydrate-rich foods – basically foods made with lots of white flour and/or too much added sugar including cakes, biscuits, lollies, pastries, sugar-sweetened soft drinks, many baked goods, burger buns and low-fibre breakfast cereals – sends blood glucose too high and this is not good for your brain or your body.
Are grains bad for your brain?
Grain foods have taken a bit of a bashing over the last few years as a result of low-carb and paleo diets and the idea that gluten is a problem for human health. There are, however, flaws in all these theories – and they are largely just theories and not based on sound scientific evidence.
The fact that some of the strongest evidence relating diet to long-term brain health supports the Mediterranean diet – a diet that includes wholegrains – is surely testament to the fact that these foods are beneficial. They are, after all, plant foods, just grass seeds, so it seems slightly odd to me that they are singled out, despite the pretty unanimous view that we should all eat more plants.
There are clear links between cardiovascular health and brain health. Many of the risk factors for heart disease also raise the risk of dementia and cognitive decline. It shouldn’t be surprising the type of diet good for the heart is also good for the brain. The evidence is compellingly in favour of wholegrains. Large-scale studies have shown that regularly eating wholegrains (not refined grains) significantly reduces the risk of heart disease and stroke.
Why we need MACs
MACs is the hot new acronym in the nutrition world, and we’re not talking about a well-known fast food burger! MACs stands for Microbiota Accessible Carbohydrates. These are carbohydrates in our food that are not broken down in the small intestine by our digestive enzymes, so they can enter the colon. There they are fermented by the microbiota (the micro-organisms in the gut), which produces a whole host of by-products – including short-chain fatty acids – and is
important not just for the gut itself, but also has a knock-on effect throughout the body, including for the brain.
This is because the by-products of this fermentation are involved in the communication between the gut and the brain. Think of them as signalling chemicals, carrying messages to the brain from the gut. This “gut-brain axis” seems to play a role in regulating mood, appetite and potentially other aspects of mental health. We have long known that diet influences mental health, we just didn’t know how. Undoubtedly, supplying nutrients is important, but this new research strongly supports the idea that the microbiome (the genes of the microbiota) is also involved.
MACs are essentially fermentable fibres. These include resistant starch and most soluble fibres. Resistant starch is found in firm bananas, legumes (lentils and beans), the CSIRO-developed super grain, BARLEYmax, and in cooked and cooled potatoes, pasta and rice. Soluble fibre is found in many fruits, vegetables, legumes and wholegrains, including oats and barley.
What is interesting is that your own unique microbiota can also affect whether a particular carbohydrate is a MAC or not. Not all micro-organisms can ferment all carbohydrates. The Japanese have particular strains of bacteria that are able to ferment an indigestible carbohydrate found in seaweed, so this becomes a MAC to them. However, most people in Australia, the US and Europe do not have these particular microbes and, therefore, the seaweed carbohydrate is not a MAC for us, and it passes straight through. This is an example of how we’ve evolved alongside our microbiota, as it adapts to our diets, which helps them and us survive and thrive.
It’s crucial to consume a broad range of MACs to nourish your microbiota. In addition to gut-brain communications, the by-products of fermentation play an essential role in immune function, in the health of the gut, and in controlling blood glucose and cholesterol levels. So a diverse diet of MACs supports a diverse range of micro-organisms, and that seems to be key for health.
Researchers have found there is a loss of diversity in the microbiome of those living a modern urban lifestyle compared to those living a more traditional rural lifestyle. Many factors are thought to be involved, but what we eat is key. Increasingly processed, low-fibre diets have literally led to the extinction of many micro-organisms.
The full impact of this is not yet understood, but it is thought to play a role in the rising incidences of gut problems like IBS, auto-immune disorders, allergies, food intolerances and, possibly, some mental health problems.
Low-carb diets and those that restrict wholegrains and legumes are also restricting MACs. This changes the microbiota and restricts the growth of bacteria known to be associated with positive health outcomes. Studies of traditional lifestyles around the world, either today or in the past, find that most have a high intake of a diverse range of plant foods containing lots of different MACs, in comparison to typical Western-style diets.
THIS IS AN EDITED EXTRACT FROM BRAIN FOOD BY DR JOANNA MCMILLAN, RRP $35. AVAILABLE AT MAGSHOP.COM.AU AND WHERE ALL GOODBOOKS ARE SOLD.