The brain is a blood-hungry, glucose-hungry, and oxygen-hungry organ. It requires 15% of our total cardiac output, 20% of our total oxygen consumption and 25% of our total glucose use. The circulatory system is thus preeminent in maintaining good brain function. Factors that improve blood supply help the brain and, conversely, factors that impair blood flow hurt the brain.
The brain is also a fatty organ and is thus susceptible to the ravages of oxidative stress and inflammation. Food, sleep, stress, and smoking all play a role in promoting or helping to reduce oxidative stress and inflammation.
Exercise boosts brain function in just about every way that we can measure brain function. Research has consistently shown that exercisers outperform couch potatoes in tests that measure long-term memory, reasoning, attention, problem-solving, creativity, and fluid intelligence.
Regular exercise has also been shown to improve mood states—i.e., it helps reduce anxiety, depression, and pessimism. Conversely, it improves optimism and self-efficacy.
How exercise improves brain function. Exercise has also been shown to induce angiogenesis (or the creation of new blood vessels) in the cerebellum, hippocampus, and the motor cortex. Angiogenesis declines with age, thus exercise can prevent this decline.
New blood vessels improve blood flow, which improves oxygen and nutrient delivery (the hippocampus, which is essential for memory formation, is highly dependent on oxygen) as well as better removal of waste. Increased blood flow velocity (as occurs during exercise) is significantly associated with less cognitive decline and whereas lower velocity is associated with Alzheimer’s disease.
Aerobic exercise also has been shown to increase the production of neurochemicals that promote growth, differentiation, survival, and repair of brain cells. There are several neurochemicals that help to mediate the benefits of exercise on brain health, including brain-derived neurotropic factor or BDNF. BDNF increases in response to both acute (a single bout) and chronic (regular) exercise. BDNF keeps existing neurons young and healthy and encourages the formation of new cells in the brain—particularly in the hippocampus. In short, exercise nourishes the brain.
Aerobic exercise also enhances several neurotransmitters in the brain, including circulating dopamine, serotonin, norepinephrine, and acetylcholine. These neurotransmitters play a role in mental health and mood enhancement and wakefulness, among other things.
- The bottom line: Increase physical activity by moving more during the day (a step counter can help with this) and by engaging in regular intentional exercise that is varied in duration, intensity and mode—e.g., do intervals 1-2x per week, sustained endurance exercise 2-3x per week, yoga and/or resistance training 1-3x per week. The key is consistency over time. Finally, sit less and move more. Get up every 20-60 minutes and stand, move, or walk.
Eat more whole plant foods. Why? All plants, including fruits, nuts, beans, spices and leafy greens make a vast array of chemical compounds that serve to enhance a plant’s survivability. This includes combating oxidative stress and inflammation
Some of the plant foods studied most for their effect on brain function are blueberries, strawberries, grapes, blackberries, walnuts, green leafy vegetables, green tea, and the spices turmeric and saffron. All have been shown to have beneficial effects, such as improving working memory, staving off or reversing cognitive decline, neurogenesis, and the ability to manage complex learning tasks, to name a few of the reported benefits.
A 2010 paper that was eight years in the making reported the antioxidant content of 3,100 foods. Iceberg lettuce, one of the most antioxidant-poor vegetables, has more antioxidant units than the same amount of milk, eggs, salmon, chicken or beef—all foods eaten to excess in western countries.
When the researchers averaged the antioxidant content of plant versus animal foods, the plants won hands down. Plants averaged 1,157 antioxidant units per 10 grams, while animal foods averaged 18. Plants make antioxidants; animals don’t.
As the adage goes, plants are nutrient producers, animals are nutrient consumers. Some of the most antioxidant-rich foods are dark leafy greens, berries, spices and herbs, and beans. Fiber has also been shown to be helpful for brain function. It helps to regulate blood glucose levels. One study found the presence of fiber in the diet is associated with higher alertness ratings and less perceived stress. High-fiber foods are beans and cooked whole grains.
Eat fewer (a whole lot fewer) animal foods and processed foods.
Not only are animal foods devoid of free radical-fighting nutrients, they also contain substances that are harmful to brain health. Saturated fat (mostly sourced from meat and dairy) and cholesterol (only found in meat and dairy) consumption have been shown to double one’s risk of Alzheimer’s disease (AD).
In those with a genetic predisposition for AD, high fat diets increased risk by a factor of 6. In a review paper, total fat (mostly from animal sources) was most strongly associated with increased risk for Alzheimer’s, while cereal or whole grain intake was inversely associated with risk.
But when it comes to animal foods, their fat and cholesterol content, while troublesome, is only part of the problem.
AGEs likely pose a bigger threat to brain health. Advanced glycation end-products (AGEs) are cross-linked proteins that damage neurons and increase oxidative stress and inflammation within the brain. They are also aptly called AGEs as they promote aging.
In fact, scientists refer to them as gerontoxins, or aging toxins. Skin wrinkling is in part caused by AGEs that have built up in the collagen tissue. AGEs wreak their havoc by increasing free radical damage and inflammation and have been implicated as being one of the causative factors in AD.
AGEs can enter our bodies when we eat foods that contain them. They are formed when meats are cooked at high temperatures, such as frying, roasting, searing, broiling or grilling. Cooking foods in water or cooking foods with a high water content limits their formation. Fresh plant foods, for example, contain very low amounts (if any). Boiling meat has been shown to limit their formation, whereas broiling meat promotes their formation.
When it comes to AGE content, foods that top the list are roasted chicken, bacon, fried steak, and hamburgers—all foods that loom large in western diets. Just by way of comparison, a burger has almost 5,000 units, a Boca veggie burger has 20. Foods that contain carbohydrates, like beans, fruits, and vegetables, have very low AGE concentrations. This could be why those eating plant-based diets have been shown to have 1/3 the risk of Alzheimer’s disease as those eating even moderate amounts of chicken and fish.
Animal foods can also promote inflammation, as they contain high levels of pre-formed arachidonic acid or AA. AA results in the production of pro-inflammatory eicosanoids. Processed oils, which are high in omega-6 fatty acids, are converted to AA and can promote inflammation as well. Oils, including olive oil, have also been shown to hurt endothelial (or arterial function).
Fish consumption is generally recognized to be heart and brain healthy. However, eating fish, while generally better than eating chicken and beef, is not the health food it is made out to be. Our oceans and waterways have become the sewers of the world, leading to widespread contamination. Fish oils are highly contaminated (even if the label says otherwise) and so are fish.
All fish now contain traces of mercury and other pollutants like PCBs, dioxins, heavy metals, and DDT to a greater or lesser degree. But while fish are a primary source, they are not the only source.
Consumption of food is the major source of non-occupational exposure to these pollutants with foodstuffs from animal origin accounting for more than 90% of the human body burden. Thus meat, dairy, and fish products are the primary culprits, with fish likely being the worst.
- The bottom line: The good news is that the same diet that has been shown to prevent the progression and even reverse heart disease—i.e., a whole-foods, plant-based diet, is the same diet that will help improve brain function and reduce the risk of neurodegenerative diseases like Alzheimer’s and vascular dementia.
Transferring the Learning
So, as a leader, what can I do to take better care of my brain?
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