It seems like everyone these days is after a magic bullet in the form of a common yet delicious food that will cure us of all our health-related problems, prolong life, and make us smarter. Well, I can tell you before you read any further that there isn’t one. At least not one that is capable of reversing years of unhealthy living. However, there are a few dietary choices we can make that can help in achieving all those goals!

How fat can damage the brain

Saturated fat and the brain

Dietary fat is essential for our well-being. The walls of our cells are made up of fats; our adipose tissue provides energy storage and temperature regulation; and fats that we ingest help us absorb essential vitamins. However, too much fat in our diet can make us… well… fat. It can also damage our brains.

If we eat more fat in our diet than we can easily convert into energy and use, this fat is stored in our adipocytes (fat cells), making us gain weight and ultimately changing the way our bodies process energy. As well as having a range of negative effects on the rest of the body, the excess fats in circulation can access the brain and damage our brain cells¹.

The main part of the brain that processes information on whether you are hungry or full is called the arcuate nucleus. The arcuate nucleus sits in a region of the brain that has very good access to factors circulating in the blood stream². When fats that we eat enter the arcuate nucleus from the blood stream, they activate the brain’s immune cells. In the very short term, this process is an adaptive one and the immune cells clear away the fat, maintaining good brain health¹.

In the longer-term, though, if we keep eating lots of fatty foods as part of our normal diet, these immune cells become over-active and start damaging the brain. The brain cells that become damaged are those very cells that are important for telling us that we are full and should stop eating^{1, 2}. Too much fat in storage also disrupts the hormonal signaling that would normally tell us to stop eating³.

Without these cells and the normal interplay of satiety hormones, we continue to feel hungry and so continue to eat to excess. Eventually, other parts of the brain can see the effects of too much of a high fat diet, with potential damage to memory, cognitive function and emotional processing. This can occur either directly (by excess fat getting into the brain) or indirectly (by connections to memory and emotion regions from the arcuate nucleus being damaged)².

How sugar can damage the brain

A recent study has now suggested that it is not just fat that can damage our brains, but sugar. By testing different combinations of diets in model systems, a team from Germany and the Netherlands was able to show that high sugar (or high starch) in combination with high fat caused brain inflammation and cell damage in the arcuate nucleus, but that high fat alone did not damage the brain⁴. Studies like this show that dietary excess in almost any direction can be bad for our brain health.

Berries for brain health

Berries for brain health

The encouraging news is that the damage caused by poor diet is somewhat reversible over time if a healthy diet is resumed. There are also some specific common foods that can help.

For example, fruits and vegetables contain polyphenolic compounds that have antioxidant and anti-inflammatory activities. These ingredients can then reduce activation of the immune cells that might damage our neurons⁵.

Berry fruit in particular, including blueberries and strawberries, also contain anthocyanins and flavonoids that are highly anti-inflammatory.

High intake of foods rich in anthocyanins and flavonoids can reduce weight gain in adults⁶. In addition, berry fruit can improve brain function. In double blind, placebo-controlled, randomized human intervention studies (where neither the study participants nor the experimenters knew what experimental food they were being given) blueberry juice concentrate improved memory and learning in older adults⁷. Blueberries can also improve memory in children⁸.

These findings support the idea that a handful of berries on a daily basis can be great for brain health. Anthocyanidins are even concentrated in the skin of blueberries and other red and blue berries and contribute to the strong colouring, giving us a handy way to tell which berry fruits might be the best to select.

It’s important to note, though, that even bucket loads of blueberries cannot completely reverse a lifetime of damage. A well-rounded, healthy diet on a day-to-day basis throughout life is the best approach, including moderate proportions of fats. And it’s nice to know, too, that our brains are actually pretty good at cleaning up after the occasional unhealthy meal.

References

1. Thaler JP, Yi CX, Schur EA, Guyenet SJ, Hwang BH, Dietrich MO, et al. Obesity is associated with hypothalamic injury in rodents and humans. J Clin Invest. 2012;122:153-162
2. Miller AA, Spencer SJ. Obesity and neuroinflammation: A pathway to cognitive impairment. Brain Behav Immun. 2014;42:10-21
3. Schwartz MW, Woods SC, Porte D, Jr., Seeley RJ, Baskin DG. Central nervous system control of food intake. Nature. 2000;404:661-671
4. Gao Y, Bielohuby M, Fleming T, Grabner GF, Foppen E, Bernhard W, et al. Dietary sugars, not lipids, drive hypothalamic inflammation. Molecular metabolism. 2017;6:897-908
5. Spencer SJ, Korosi A, Laye S, Shukitt-Hale B, Barrientos RM. Food for thought: How nutrition impacts cognition and emotion. NPJ Sci Food. 2017;1:7
6. Bertoia ML, Rimm EB, Mukamal KJ, Hu FB, Willett WC, Cassidy A. Dietary flavonoid intake and weight maintenance: Three prospective cohorts of 124,086 us men and women followed for up to 24 years. BMJ. 2016;352:i17
7. Lamport DJ, Saunders C, Butler LT, Spencer JP. Fruits, vegetables, 100% juices, and cognitive function. Nutr Rev. 2014;72:774-789
8. Whyte AR, Williams CM. Effects of a single dose of a flavonoid-rich blueberry drink on memory in 8 to 10 y old children. Nutrition. 2015;31:531-534