How the “Western Diet” Affects Your Brain

by Women's Brain Health Initiative:“You are what you eat” has become such a common refrain that it has nearly lost its potency. However, be careful about disregarding these established words of wisdom. From heart disease and diabetes to obesity and osteoporosis, it is now commonly understood that diet plays an integral role in the genesis of many diseases. Similarly, research has demonstrated that nutritional habits have a profound effect on our mental health, including depression, insomnia, and attention-deficit/hyperactivity disorder (ADHD). More recently, studies have shown that the types of food that we consume can impact our risk of developing Alzheimer’s disease and other dementias.Mounting evidence from ecological studies indicates that the contemporary Western dietary pattern – characterized by higher intakes of red and processed meat, refined sugars and grains, alcohol, and high-fat dairy products, with minimal intakes of fruits, vegetables, whole grains, nuts, and fish – is strongly associated with negative health outcomes. According to an article published in The American Journal of Clinical Nutrition in 2005, the types of foods that fall within the “Western diet” category comprise 72.1% of the total daily energy consumed by all individuals living in the U.S.Newer research conducted by celebrity chef Ricardo Larrivée, in partnership with Léger Marketing, examined the cooking and eating habits of Canadians from the west coast, Prairies, Ontario, Quebec, and the Atlantic provinces. The researchers found that while the vast majority (91%) of participants indicated that they wanted to eat a healthy and balanced diet, only one out of every ten individuals felt that their meals reached that goal. Nevertheless, the study shows that more Canadians are conscious about healthy eating than ever before. Over 55% of Canadians buy at least one organic food product every week at the grocery store, and the purchase of local vegetables grown through smaller-scale community-supported agriculture is gaining traction.The quality of our diet impacts not only our physical health but also our brain health. “Our brains require a huge number of vitamins and minerals every minute that our heart is beating; in other words, every minute we’re alive,” explains Dr. Bonnie Kaplan, a behavioural psychologist at the University of Calgary. She continues, “Approximately a litre of blood perfuses your little two-and-a-half to three pound brain every 60 seconds that your heart is beating. What is it doing? Of course, it’s bringing oxygen and taking away waste products – but it’s also bringing all the vitamins and minerals into your brain that you’ve eaten in the last few hours – and that’s every minute of every day, 24/7.” The vitamins and minerals that we intake through the foods that we eat or through supplementation “are used in every metabolic step in our brains,” says Dr. Kaplan.Most of us are familiar with serotonin, for instance, which is a neurotransmitter that boosts our mood and social functioning. But what many people do not know is that the majority of the body’s serotonin (between 80% to 90%) can be found in the gastrointestinal tract. “We don’t eat serotonin. What we eat are the precursors to serotonin,” notes Dr. Kaplan. In addition to serotonin, we require enzymes, vitamins, and minerals at each step of the process “for every chemical in your brain.”Likewise, approximately two-thirds of the brain is composed of fat, and fatty acids are among the most crucial molecules that determine the brain’s integrity and ability to perform. Although essential fatty acids (EFAs), particularly the omega-3 fatty acids, are important for brain development, they cannot be synthesized by the body and must be obtained from dietary sources. The most common food sources of EFAs include seafood, such as sardines and salmon, as well as flax seeds, walnuts, almonds, dark green leafy vegetables (such as broccoli and spinach), olive oil, whole grain foods, and eggs. “You should never eat a low-fat diet,” advises Dr. Eva Selhub, internationally recognized expert in the fields of stress, resilience, and mind-body medicine. “Every cell in your body is made up of fat. You might want to do a no-bad-fat diet but not a low-fat diet.”The medical literature indicates that traditional diets that are higher in the “good” fats, such as those found in Japan (high in fish and low in saturated fats) and the Mediterranean (high in olive oil, vegetables, and legumes), lower the risk of developing certain diseases, including cardiovascular disease and brain disease. In a 2014 study published in the Journal of Alzheimer’s Disease, the researchers found that changes in Japan’s dietary habits (due to the influx of Western foods) is highly related to the dramatic increase in Alzheimer’s disease, with the same trend being observed in other developing countries and their changes in national diets.Diets that are high in carbohydrates and sugars have also been linked to an increased risk of mild cognitive impairment (MCI) and dementia. Research out of the Mayo Clinic found that elderly individuals with relatively high caloric intake from carbohydrates and low caloric intake from fat and protein had nearly four times the risk of developing MCI, and the danger also increased with a diet heavy in sugar.Additionally, research conducted by Crane et al. and published in the New England Journal of Medicine found a correlation between higher glucose levels and an increased risk of dementia in populations with and without diabetes. The Western diet is high in both sugar and those less-healthy carbohydrates that get converted to sugar more quickly (as opposed to complex carbohydrates such as vegetables or legumes). Although the traditional Japanese diet tends to be higher in carbohydrates, too, the population also consumes a variety of healthier foods, including fish, eggs, meat, soy, and vegetables.Lower intakes of nutrient-dense foods and higher intakes of unhealthy “Western” foods have even been associated with smaller left hippocampal volume, according to recent research published in the journal BMC Med. The hippocampus is a brain area critical for learning and memory, as well as mood regulation, and is especially vulnerable to damage at early stages of Alzheimer's disease. While a growing body of clinical studies have linked eating patterns with illnesses of the brain, this was the first study to demonstrate actual changes to brain structure associated with dietary patterns.As Dr. Selhub observes, “In general when you’re eating, you’re feeding your brain. Your brain needs those nutrients more than any other organ in the body, except the heart, which comes close in terms of metabolic demand.” While consuming brain-healthy foods is critical at all ages, this becomes increasingly important as we age because our ability to absorb and utilize many nutrients becomes less efficient, as our nutrient requirements simultaneously increase. Dr. Selhub says that we should think of our brain as a Lamborghini, as opposed to a Chevy: “[The brain] needs to be fueled with really good, clean, healthy, strong, positive fuel. If you don’t feed it that way it will lose itself. If people want to live as long as we’re living and still have their brain intact, they’re going to need to cut out the processed food and the sugar from their diet.” Food for thought, indeed.Source: MIND OVER MATTER