It takes around 20 years to grow a complete human brain, from newborn baby to mature adult. Careful nurturing is a wise, lifelong investment. Although a little shrinkage is to be expected, with age, anything beyond the norm puts you at risk of memory loss and eventually dementia.
The most important area of the brain, in terms of memory, is the hippocampus. This is a complex structure buried deep within the limbic system. Damage to the hippocampus can cause it to shrink, an effect that is associated with several neurological disorders, including dementia.
Here are three dietary strategies to help you maintain a healthy brain size.
1. Regulate blood sugar, avoid type 2 diabetes
“Growing epidemiologic evidence has suggested that people with diabetes mellitus are at an increased risk for the development of dementia.”
Type 2 diabetes has long been associated with dementia. The hippocampus is highly sensitive to variations in glucose levels; diabetes and poor blood sugar control are risk factors in brain atrophy, especially atrophy of the hippocampus.
The evidence is provided by MRI scans that reveal that diabetics have a smaller hippocampal volume than non-diabetics. These scans provide a ”good estimate” of the progression of Alzheimer’s disease.
What is it about diabetes that makes it such a clear risk factor for atrophy and dementia? One likely explanation is “glucose toxicity”. Diabetics have difficulty regulating blood glucose; high levels can lead to the accumulation of substances called advanced glycation end-products (AGEs), and these can prevent neurons from working properly.
Research has found that the brains of people with Alzheimer’s disease have high levels of these AGEs, compared to people without the disease. AGEs contribute to the formation of amyloid plaques — a characteristic of the brains of people with Alzheimer’s.
To normalise blood glucose, avoid added sugar and refined carbohydrates. Starchy, sugary snacks are the worst offenders. Fructose, the sugar used in the ubiquitous sweetener HFCS, is especially heinous, despite not affecting blood glucose in the same way as other sugars. It is estimated that fructose is ten times more reactive than glucose in inducing glycation.
2. Ensure adequate B vitamin intake
“Moderately elevated plasma total homocysteine (tHcy) is a strong modifiable risk factor for vascular dementia and Alzheimer’s disease.”
Three B vitamins - B12, folate, and B6 - are essential for the regulation of an amino acid called homocysteine (Hcy). Hcy is created during the metabolism of the amino acid methionine to cysteine. It has no known use, but elevated levels are associated with a small hippocampus and are an established risk factor for brain atrophy and the development of mild cognitive impairment and Alzheimer’s.
Deficiency of vitamin B6 is uncommon, as this vitamin is widely distributed in food. Folate deficiency is more widespread and can be reversed by eating plenty of leafy green vegetables, such as spinach and kale, though the richest dietary source is offal, especially beef liver. Beans are also a good source.
Vitamin B12 is the tricky one, the one most likely to cause a rise in Hcy if it’s missing from the diet.
The main cause of low B12 is dietary avoidance. Because vitamin B12 is found exclusively in animal-source foods, the most vulnerable groups are vegetarians and vegans. Deficiency among adult non-meat eaters is common in all the different vegetarian variations.
However, dietary exclusion is not the only cause of low vitamin B12: it can also arise from gastrointestinal malfunction. Gut disorders, including Crohn’s disease and gastric atrophy, can decrease stomach secretion of intrinsic factor, essential for B12 absorption. Gastric atrophy is a condition that arises when the lining of the stomach becomes inflamed, usually as a result of an infection caused by the bacterium Helicobacter pylori.
Pernicious anaemia also inhibits B12 absorption. This is an autoimmune disorder, where the immune system creates antibodies that destroy the parietal cells of the stomach, responsible for making intrinsic factor.
The elderly are especially vulnerable to deficiency. Older people who lack B12 are more likely to experience brain atrophy, which can lead to cognitive impairment.
Large surveys in the US and the UK have found that around 6% of people over the age of sixty lack sufficient B12, and this figure increases with age.
Trials have shown that homocysteine-lowering treatment with B vitamins in elderly people with cognitive impairment markedly slows the accelerated rate of atrophy in people with memory loss, but not dementia. However, treatment is thought to be beneficial only “in those whose brain shrinkage has not yet reached critical levels and in those who do not yet have dementia.”
3. Increase your omega-3 fatty acids
“High baseline ω-3 fatty acids were associated with a slower rate of brain atrophy in the B vitamin group ….The beneficial effect of B vitamin treatment on brain atrophy was observed only in subjects with high plasma ω-3 fatty acids.”
Omega-3 fatty acids are those predominantly found in oily fish, such as salmon, herring, trout, fresh tuna, and sardines. The most important of those fatty acids is docosahexaenoic acid (DHA).
You need DHA for neurotransmitter function and the development of your cognitive skills. Neurons just won’t fire without it, and memory retrieval is a struggle. DHA accumulates in areas of the brain involved in memory and attention, including the cerebral cortex and hippocampus, and low levels are associated with brain atrophy and dementia.
In studies, red blood cell DHA (and EPA, another omega-3 fatty acid) were positively correlated with higher total brain and hippocampal volumes over 8 years.
Deficiency of DHA can affect memory, even in young adults. A team of researchers investigated whether supplemental DHA could improve cognitive performance in young people who ate little fish.
In their study, reported in The American Journal of Clinical Nutrition, A total of 176 healthy adults aged 18–45 who had a low intake of DHA were given either a daily DHA supplement, or a placebo, for six months. At the end of the study period, they were tested for cognitive performance. The researchers concluded that:
“DHA supplementation improved memory and the RT (reaction time) of memory in healthy, young adults whose habitual diets were low in DHA.”
The only good, reliable source of DHA is seafood and oily fish. Meat and eggs make a small contribution, but only from pasture-fed animals.
Although some plant foods, most notably nuts and seeds, contain fats that can be converted into DHA, the conversion rate is so low that it is considered negligible, and insufficient to meet the brain’s requirements.
Before Alzheimer’s takes hold, there is usually a pre-dementia stage called mild cognitive impairment (MCI). It is at this stage that atrophy starts to increase, and then accelerate, as MCI turns into dementia.
It is estimated that 15–20% of people aged 65 and above have MCI. About half of those people will develop dementia within five years of diagnosis.
“Modest” atrophy is normal with ageing. But with MCI, it is “markedly” faster. Step on the brakes before you get there.
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Great info, thank you Maria!
DHA supplementation improved memory and the RT (reaction time) of memory in healthy, young adults whose habitual diets were low in DHA.”
Did they mention a quantity of DHA, Maria? I take 500mg DHA, 50mg EPA daily. I'm wondering if that's sufficient.