Feed your ageing brain
Discover how diet and neurogenesis protect the aging brain. Learn why sugar harms and how Mediterranean foods help.
Songbirds have been studied for some time neurons as they learn new songs. This is a process called “adult neurogenesis”, and it was first described in the 1980s by a researcher named Goldman while studying neuroplasticity in canaries. Goldman and others soon identified that proteins such as brain-derived neurotrophic factor (BDNF) allow this to happen by causing progenitor cells in the brain to differentiate and produce neurons. These researchers showed that BDNF and another protein called Noggin (NOG) when given to adult mice, would cause the same neurogenesis. The same process was then shown to operate in primates and, guess what, that includes humans. Just like canaries learning a new song, adult humans can lay down new neurons. We know that in areas of the human brain such as the olfactory bulb (smell) and the hippocampus (memory and cognitive processes), new neurons can grow throughout life.
In other words, ageing does not need to be synonymous with a decline in mental abilities. The keyword in that sentence is “need”, because, while it doesn’t need to be, it sadly often is the case. A significant factor in how your brain ages is your diet, so it is worth thinking about what foods harm your brain and what foods help it.
Say “no” to sugar
It is a shame to begin with a negative, but the fi rst thing you really need to do if you want to protect your brain as you age is to ensure that you eat as little refi ned sugar as possible. Yes, we have evolved to love sugar because it is kilojoule-rich and was once scarce. Today, however, we eat a lot of processed foods, and sugar is often hidden there to enhance taste but not necessarily health. One of the big ageing effects of sugar is its role in the formation of advanced glycation end products (AGEs).
To understand AGEs, we need to think for a minute about proteins, because AGEs are formed when sugar attaches to proteins. This process is called glycation, and the molecule that is formed (an AGE) has no function. Normally, proteins and sugars can interact without causing damage to the body but when sugar levels are high, problems can occur.
Since proteins are present throughout the body, the destructive capacity of AGEs is enormous. These AGEs become deposited in body tissue, causing it to become “glycated”. This glycated tissue is tough and infl exible and lack of fl exibility in organ tissue leads to dysfunction of that organ. Additionally, glycated tissues then produce more AGEs, which further compound the problem by producing large numbers of free radicals, reactive molecules that cause oxidative stress.
In the case of Alzheimer’s disease, it seems that the formation of AGEs and oxidative damage is significant in the formation of beta-amyloid plaques and neuronal tangles associated with the disease. Biopsied brains of Alzheimer’s patients show a high concentration of AGEs compared to normal brains. Additionally, recent research 27 has shown that AGEs form early in the disease process for Alzheimer’s.
Outside of Alzheimer’s, research has shown that high blood sugar levels are linked to brain shrinkage in the hippocampus and the amygdala. These are the areas of the brain involved in memory and cognitive skills. After controlling for other factors, such as high blood pressure, smoking and alcohol use, high blood sugar levels, even at the high end of “normal”, have been shown to cause brain shrinkage of between six and 10 per cent.
The biggest thing you can do to reduce the formation of AGEs, and your blood sugar levels, is to cut down on simple sugar intake. If you really must have your sweetness, the plant stevia can be a good alternative.
Stevia (Stevia rebaudianai)
There are a range of plant molecules that taste very sweet to humans, but which are not carbohydrates. The best known is stevioside, a glycoside which is present in the leaves of the South American plant Stevia rebaudiana. For at least 400 years, this plant has been used by the indigenous populations of South America with no adverse side effects. As the herb, it has also been shown to regulate the pancreas and blood sugar levels, thereby reducing cravings for sugars and fats. Purified extracts (which do not have the therapeutic properties of the plant) have been used as safe alternative sweeteners in the food industry in Japan for decades. Stevioside has been shown to be 300 times sweeter than sucrose without the kilojoules and without the potential problems associated with excess sugar consumption. Stevia is heat-stable and can be used in anything where sugar can be used such as in a cup of tea or coffee or in baking.
Eat for your brain
While we know that sugar is bad for your brain, we also know that there are many foods that help your brain age well. Research has shown that health-promoting foods can stimulate neuron growth. For instance, polyphenol compounds (from foods such as tea, grapes, wine, olive oil, cocoa, nuts, fruits and vegetables) and polyunsaturated fatty acids (from fish, corn, soybeans and sunflower seeds) lead to significantly higher rates of neuron growth in both the olfactory bulb and hippocampus. Diets high in these types of foods will keep your brain biologically young. An example of this is the Mediterranean diet.
The Mediterranean diet
There is evidence suggesting that Mediterranean- style eating may keep your brain sharper as you age. The basis of the Mediterranean diet is a lot of fruits, vegetables, legumes (beans, peas, lentils), olive oil, fish and a little wine. Typically, red meat does not play a major part in the Mediterranean way of eating, although it is eaten perhaps once a week and is almost always lean. From the fruit and vegetables in this diet, you get nutrients including antioxidant polyphenols and fibre. Legumes are a protein source and help balance blood sugar, as we shall see later. Olive oil yields healthy monounsaturated fats as well as antioxidants. FishWellBeing Image: Pexels 28Body • Ageing Brain
provides protein and healthy omega-3 fats, while wine (in moderation) offers antioxidants.
Studies have shown that people who eat a Mediterranean diet have slower rates of cognitive decline. It all happens because the antioxidants and healthy fats in the Mediterranean diet reduce the oxidation and inflammation that contribute to conditions such as Alzheimer’s disease. The high levels of plant foods featuring polyphenols also support new neuron growth as you age.
Omega-3 fats
Omega-3 fats deserve honourable mention when it comes to keeping your brain healthy. The optimal source of omega-3s is fish but you can also get them from plants such as chia and flax seeds.
We know that omega-3 fats accumulate in your central nervous system when you are in the womb. It has been assumed that these fatty acids are replaced continuously throughout your life, although little is known about how this occurs and some diseases are known to impact the fatty acids in the brain. Alzheimer’s disease is associated with lower-than-normal concentrations of the omega-3 fat docosahexaenoic acid (DHA). Studies show that taking omega-3 supplements can reduce inflammatory markers in the cerebrospinal fluid of people with Alzheimer’s disease.
There has been evidence that fish oil and its omega-3 fatty acids can benefit conditions such as ADHD in children. Research has also shown that supplementing with fish oil can change the brain structure of adults. Studies have shown that taking fish oil supplements leads to better cognitive function and larger brain volumes in the cerebral cortex and the hippocampus, brain areas involved in cognitive function and memory.
Oranges and lemons
Citrus sinensis is the common orange we eat but there are many other varieties with different uses. Although famous for its vitamin C content, the orange fruit also contains other substances that support your brain such as antioxidant and anti-inflammatory compounds, including flavonoids. Red (blood) oranges have much higher levels of the anti-inflammatory anthocyanidins. Although they do contain many nutrients that support brain health, it does seem that the good old vitamin C from oranges might be the thing that makes them useful in warding off one of the potential brain diseases associated with ageing: Alzheimer’s.
The theory goes that Alzheimer’s results from brain changes that occur as a result of amyloid plaques that accumulate in the brain. It is thought that these plaques and the changes that result from them might be due to oxidative stress, so antioxidants should theoretically be of some help in preventing Alzheimer’s occurring. Research has shown that vitamin C and betacarotene levels are much lower in people with Alzheimer’s. It could be that vitamin C and betacarotene selectively act against the oxidative drivers of the Alzheimer’s process. If you want to increase your vitamin C intake, get stuck into foods such as oranges, lemons, spinach, broccoli, capsicum, strawberries, papayas and carrots.
Lovely legumes
Legumes are a big family of foods including peas, beans, chickpeas, alfalfa and lentils. There is evidence that legumes will help your brain as you age, primarily because they will balance your blood sugar levels, and we have seen how damaging high blood sugar levels can be to brain function.
Legumes, also known as pulses, provide protein, B vitamins, iron, calcium, zinc and magnesium and are high in soluble fibre. They have a low glycaemic index (GI), meaning that they are broken down slowly, so you feel fuller for longer, making them a particularly good food for preventing and managing diabetes. Studies tell us that adding legumes to the diet causes drops in blood sugar levels, and that is good news for your brain.
Lentils
Lentils are a small but nutritionally large member of the legume family. They are an excellent source of fibre, as well as a good source of folate and the mineral iron. You also get a good dose of B vitamins from lentils and the whole nutritional package comes at the expense of very few kilojoules. The other great benefit of lentils is that they are quick and easy to prepare.
Peas
Like lentils, peas are low in fat and kilojoules but high in fibre and packed with other nutrients. Although peas are so common that we may take them for granted, we now know that green peas contain unique and powerful antioxidants. In fact, the lowered risk of type 2 diabetes associated with legume and pea eating is probably thought to arise from not only their high fibre content but this unusual combination of antioxidant and anti-inflammatory compounds as well. The other bonus for your brain is that green peas are a decent source of omega-3 fats in the form of alpha-linolenic acid (ALA).
Believe in your brain
Although this article has focused on food, it is true that other factors drive ageing in your brain. Adequate sleep, regular physical exercise and continuing to use your brain (with things such as crosswords and problem-solving) all lead to a better ageing brain. It is also important that you believe you can help your brain to age well. Research has shown that people who are told that ageing has negative effects on the brain will do around 20 per cent worse on a test given immediately afterwards than people who were not told this. It is a case of self-fulfilling prophecy: someone believes their brain won’t function well as they age and so it doesn’t. However, if you eat well, then you are on the way to having a brain that will serve you well for a lifetime.
