One of the underlying causes of most diseases is inflammation, and neurological disease is no exception. The following foods interfere with brain health by inhibiting its natural processes, creating inflammation, and slowing down cognitive function...
1. Refined Carbohydrates
Refined carbohydrates include everything from white bread to pasta, pastries to cookies, and everything in between.
Basically, if it's rich in carbohydrates and isn't a whole food (like a potato, rice, quinoa, etc.), it's probably a refined (or processed) carbohydrate.
Why are these foods so tough on your brain?
Refined carbohydrates are often rich in either pure sugar or complex carbohydrates that have been broken down so that they can be digested and absorbed like simple sugars. This creates an influx of sugar (glucose) in your bloodstream.
While glucose, which comes from carbohydrates, is your brain's primary source of fuel, too much sugar can lead to neurological issues like memory impairment and dementia (17).
Some potential mechanisms by which refined carbohydrates and the resulting influx of sugar can impair brain health include (18):
- Dysregulation in metabolic functions (leading to issues like diabetes)
- The formation of advanced glycation end products (AGEs)
- The increased risk of inflammation
- Reduced brain-derived neurotrophic factor (BDNF) (which plays a vital role in the growth, maturation, and survival of brain cells, as well as neuroplasticity)
When blood sugar is not controlled, as is the case in diabetes, neurological issues may arise due to the impact of sugar on the central nervous system. Some examples include depression, anxiety, and cognitive deficits. Some research even suggests that diabetes medication could assist in the management of diseases like Alzheimer's and Dementia (19, 20).
Advanced glycation end products (AGEs) are the result of chemical reactions between sugar and proteins. When you have too much blood sugar in your body, it can react with proteins in your tissues and result in the formation of AGEs.
AGEs are incredibly harmful to your body, instigating inflammation, oxidative stress, and impairing mitochondrial function. They can target any of your organs, and research shows that there is a link between AGEs, Vascular Dementia, and Alzheimer's disease (21, 22).
Diets high in sugar are also correlated with reduced levels of BDNF. As previously mentioned, BDNF plays a crucial role in the health of your brain cells, allowing them to grow and mature. Furthermore, it assists in neuroplasticity, which is a function of your brain involved in memory and learning (10).
Research shows that there is a thread between diets high in sugar, reduced BDNF expression, and resulting memory deficits (23).
2. Sugary Drinks
Right along the same lines as processed or refined grains are sugar-sweetened beverages.
Research shows that sugar-sweetened beverages (SSBs) are associated with a cognitive decline for much the same reasons that refined carbohydrates are—they're rich in sugar (24). And truly, with 25 to 40 grams of sugar per can, soda may be one of the most potent sources of sugar on the market today.
To make matters worse, it appears that the intake of soda and other SSBs is only increasing, with around 60% of youth and 50% of adults in the United States consuming at least one SSB per day.
In addition to the vast research on sugar and cognitive decline, studies have also shown that SSBs, specifically, were positively correlated with risk for dementia, Alzheimer's, and stroke (25).
What's more, it appears that even the "diet" versions of sugar-sweetened beverages may have an impact on brain health, with research showing a link between artificial sweeteners and ischemic stroke, all-cause dementia, and Alzheimer's Disease (26).
3. Processed Meat
Research shows that processed meat, but not unprocessed meat, is linked to a higher risk for both dementia and Alzheimer's disease (27).
Processed meat includes deli meat, sausages, bacon, hot dogs, salami, and more. While it's not necessarily the meat itself that's the issue, the ingredients that are added to processed meats like nitrates and sodium can increase inflammation in your body (28, 29).
These flavor enhancers and preservatives can also increase your blood pressure, which results in hypertension—a risk factor for dementia (30).
In fact, long-term research suggests that high blood pressure during mid-life significantly increases your risk for dementia in later life (31).
4. Fried Food
Fried food is probably one of the worst offenders when it comes to brain health or the health of any organ, for that matter. With fried food, you get a combination of processed carbs, sugar, low-quality fats, and AGEs (29).
Regardless of what you're frying, fried food typically involves high-heat cooking methods with low-quality oils and some type of carbohydrate. It's pretty rare that you'll come across fried food that's cooked with heat-stable fats like butter or avocado oil. Instead, most fried food is made with soybean oil or canola oil. These oils are much less stable and, when heated, can produce trans fats.
Research shows that trans fat consumption can result in cognitive impairment and memory loss, even for generally healthy young adults (32, 33).
And, of course, trans fats, in combination with the detrimental effects of AGEs and simple sugars, make a recipe for disaster when it comes to cognitive health (34).
The most common fried foods to watch out for include french fries, chicken nuggets, fried chicken, tempura sushi, fried calamari, and onion rings—but almost every cuisine has its fried culprits.
