Following a healthy diet is essential to maintaining optimal brain health. Avocados and fatty fish; bone broth, berries and broccoli – they’re all brain-boosting superstars. But there are plenty of foods that have the opposite effect and can sap your smarts, affecting your memory and mood. Therefore, it’s important to cut or reduce the following food from your diet to mitigate their effects.
Fried chicken and French fries won’t just widen your waistline, they are also bad for your brain. In a study published in 2016 in the Journal of Nutritional Science, people who ate diets high in fried foods scored poorly on cognitive tests that evaluated learning, memory and brain function. Conversely, those who ate more plant-based foods scored higher.
“Scientists think it may have something to do with inflammation and reduction in brain tissue size,” says Kristin Kirkpatrick, co-author of Skinny Liver. “When you look at aspects of one of the great brain studies – the MIND diet – it clearly shows which foods may cause or reduce inflammation in the brain. Fried foods are on the NO list, while berries, olive oil, whole grains and food containing omega 3 are on the YES list.”
You probably know to stay away from soft drinks. But you should also beware of fruit juice, energy drinks and sweet tea. Why, you ask? The same reason soft drink is among the bad foods for your brain: sugar.
“High amounts of sugar causes neurological damage” because it triggers inflammation, says the Academy of Nutrition and Dietetics’ Wesley Delbridge. A study published in 2017 in Alzheimer’s & Dementia backs that up. Researchers found that people who regularly consume sugary drinks are more likely to have poorer memory, smaller overall brain volume, and a significantly smaller hippocampus – the part of the brain important for learning and memory – than those who don’t.
Instead of drinking fruit juice or sweet tea high in sugar, try sweetening water or tea with slices of oranges, lemons, or limes.
White rice, white bread, white pasta and other processed food with a high glycemic index don’t just cause major spikes in blood sugar, they also rank with the ‘bad foods for your brain’. Specifically, these foods can have a negative effect on your mental health. A study, published in 2015 in The American Journal of Clinical Nutrition found that food with a high glycemic index can raise the risk of depression in post-menopausal women. Women who ate more lactose, fibre, fruit and vegetables, on the other hand, showed a significant decrease in symptoms of depression.
Swap the white carbs for complex carbs like whole wheat bread, brown rice, quinoa, barley, and farro. All of these contain fibre, which nurtures your gut bacteria and regulates inflammation – all good things for your brain health.
There is a sweet spot for alcohol consumption, according to neurologist Dr David Perlmutter and author of Grain Brain: The Surprising Truth about Wheat, Carbs, and Sugar. While the occasional glass of red wine is okay, drinking in excess can be toxic to your brain function, no matter your age. Research, including a study published in 2017 in the peer-reviewed medical trade journal BMJ, found that moderate drinking can damage the brain. The hippocampus is particularly vulnerable.
To protect your brain, limit alcohol consumption to no more than one standard drink per day for women and two per day for men. According to Australia’s national alcohol guidelines, one standard drink is defined as containing 10 grams of alcohol.
Instead of a sugar-sweetened beverage, maybe you turn to the occasional diet soft drink. But make a habit of it and you could be upping your risk of dementia and stroke, suggests a study published in 2017 in Stroke. Researchers found that participants who drank diet drinks daily were almost three times as likely to have a stroke or develop dementia when compared to those who didn’t.
“We seek out diet soft drinks for its sweet delivery of liquid,” says Kirkpatrick. “That sweet taste remains on our taste buds, making us crave more.”
To kick the habit, she suggests going cold turkey. “Eliminate all sources of sweet from the taste buds to retrain the brain not to want it in the first place,” she says. “Sprucing up water with lemons, limes or berries, or having flavoured seltzer without added sugar can help, as well.”
If you like to eat processed meats, you may run a greater risk of developing dementia, suggests an April 2020 study published in Neurology. Although the study does not prove cause and effect, the researchers found that dementia was more common among participants who ate highly processed meats, such as sausages, cured meats and pâté. People without dementia were more likely to eat a diverse diet that included fruit, vegetables, seafood and poultry, according to the findings.
Highly processed foods are most likely the primary cause of results linked to the reduction in brain tissue size and inflammation, which impacts brain health, says Kirkpatrick.
For starters, the high levels of saturated fat found in greasy burgers and fries can make it harder to fight off Alzheimer-causing plaque. Plus, the level of sodium found in the average fast-food fix can cause brain fog. How so? High blood pressure, often brought on by eating too many salty foods, can restrict blood to the brain and negatively impair focus, organisational skills and memory, suggests a review of studies published in 2016 in Hypertension.
To break a fast food habit, Kirkpatrick suggests this trick: “Start with altering what you order,” she says. “Avoid fried options and opt for more whole grains and plants.” Then reduce the number of days you buy fast food by half.
While the occasional tuna sandwich is no big deal, you might want to think twice before making it your go-to lunch. That’s because tuna – as well as swordfish, shark (flake), bill fish and deep sea perch – has higher levels of mercury than many other types of seafood. A study published in Integrative Medicine shows that people with high levels of the heavy metal in their bloodstream had a 5% drop in cognitive function.
But you don’t have to banish seafood from your plate forever. Advice from Food Standards Australia New Zealand (which reflects the fish we eat in our region and its mercury content) recommends 2-3 serves per week of fish and seafood, including canned or fresh tuna (one serve equals 150g), except for fish such as orange roughy (deep sea perch), catfish, shark (flake) or billfish (swordfish/marlin), which you should only consume 1 serve per week and no other fish that week.
Try swapping these varieties of fish for omega-3-rich sources such as wild salmon and lake trout, which have been associated with better brain health, says Kirkpatrick.
This article originally appeared on Reader’s Digest.