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