Food, inflammation and mental health

We know that nutrition is related to aspects of mental health and that all of our cells, bones, and tissues are built from what you eat- and this includes signalling molecules. An example is that dietary fat is important in building and maintaining brain tissue and also aids in balancing hormones. Vitamins and minerals obtained from foods are used to create energy and send electrical impulses along neurons, which enables us to move, think and essentially function. So if food affects our brain it is reasonable to think that food may be implicated in mood disorders.

One of the worst things we can do for our mental health is to consume foods that are known to be inflammatory as we know that inflammation is associated with depression and Bipolar Disorder, amongst others (1).   The relationship is not clear as we don't know whether inflammation causes poor mental health, or if pathologies such as depression, cause inflammation.

We do know that nutrition is related to the health of our gut microbiome, and that inflammation can cause leaky gut syndrome- which is when the tight junctions intestinal epithelial lining is compromised, and allows the passage of toxins, antigens, and bacteria in the lumen to enter the bloodstream.  So if you have leaky gut syndrome then some tiny particles which should never be able to enter your bloodstream can travel through. The problem is that this can cause chronic inflammation, which is associated with most disease states- including mental health conditions. '

There have been several studies suggesting that if we eat an anti-inflammatory diet we may have significantly lower risk of depression . A longitudinal study conducted over 12 years, reported that women eating an anti-inflammatory diet had a 20% lower risk of developing depression than their peers (2). Recently, results from a randomised control trial indicate that dietary improvement, guided by a clinical dietician, may provide a positive treatment strategy to prevent and treat depression (3). To increase diet quality participants in the study were supported to consume the following 12 key food groups - most of them 'anti-inflammatory' foods (recommended servings in brackets): whole grains (5–8 servings per day); vegetables (6 per day); fruit (3 per day), legumes (3–4 per week); low-fat and unsweetened dairy foods (2–3 per day); raw and unsalted nuts (1 per day); fish (at least 2 per week); lean red meats (3–4 per week), chicken (2–3 per week); eggs (up to 6 per week); and olive oil (3 tablespoons per day). Intake of 'extras’ foods, such as sweets, refined cereals, fried food, fast-food, processed meats and sugary drinks (no more than 3 per week) were reduced. This study highlighted the relationship between consuming healthy food groups and a reduction in major depressive episodes.

The evidence for an 'anti-inflammatory diet' is not confirmed, although it has been observed in many cases. Although there are many foods that we know reduce inflammation such as turmeric, fish, blueberries, ginger, green tea, dark chocolate, and some vegetables, these foods are investigated alone, rather than as part of a diet. University of South Carolina epidemiologists James Hébert and Nitin Shivappa came up with a Dietary Inflammatory Index. To do this they surveyed 1,943 studies looking at the anti/pro inflammatory profiles 45 food elements. This tool has been used to correlate the relationship between certain foods and markers of inflammation.  Briefly, diets that score high positive on the inflammatory index such as a fast food diet are pro-inflammatory and those that score high negative on the index, such as a macrobiotic or Mediterranean diet are anti-inflammatory (4). The research tool can be used for evaluating diets, however it is built from studies that vary widely in methodology.

So back to foods that can promote depression through inflammation. The first one (and one very close to my heart) is sugar.  Sugar is so addictive and we are not designed to handle the blood sugar levels that we imposing on ourselves. When you eat that snickers bar- or even eat a sandwich,  your blood sugar increases quickly.  The pancreas then has to secrete insulin as the job of insulin is to remove blood glucose and move it to our muscles. When insulin removes blood sugar, we crash and burn (remember that feeling after eating a high sugar snack), and cortisol comes in to compensate and try to move sugar out of storage and back into the bloodstream. This process, often called reactive hypoglycemia, is responsible for carb and sugar cravings. Unlike fat cells, the brain can’t store glucose, so it is readily burned up upon use.  Our brain cells need twice the energy of other cells in your body and it is very sensitive to changing blood glucose levels, which leads to anxiety, headaches, irritability, and depression.

An early study in the British Journal of Psychiatry  involving 3400 middle-aged civil servants, reported that those who had a diet that contained a lot of processed foods (high sugar) – ranging from desserts to refined grains – had a 58 percent increased risk for depression, whereas those whose diet could be described as containing more whole foods (veggies, fruits and fish), had a reduced risk for depression of 26 percent (5). Overall, high blood sugar causes inflammation, which is one of the most significant risk factors for depression. It woulds seem that there is plenty of evidence to indicate that that mood disorders are linked with inflammation (6).  I personally notice that when I have had more chocolate or sugar than I should, that my moods are more unstable - which is dangerous ground for anyone who already struggles with mental health issues. Eating good quality, nutritionally sound food will help lower inflammation and stabilise blood glucose levels.

Artificial sweeteners. The arguments I have had with colleagues and friends on the merits (or lack of) of artificial sweeteners. I personally think that to eat or drink anything that is named "artificial" is asking for trouble. We would be better to cut down our intake of sugar and reduce our need for 'sweet' rather than substitute it.  There is some evidence that Aspartame blocks the production of the neurotransmitter serotonin and so then causes mood dips, headaches, and insomnia.  Although it would seem that there are no conclusive links between artificial sweeteners and cancer, studies to investigate this were conducted using far smaller amounts of diet soft drink than the 24 ounces a day consumed by many people who drink diet drinks. We have no way of knowing what effect large amounts of these chemicals will have over many years. And there are other health concerns beside cancer. In the Multiethnic Study of Atherosclerosis, daily consumption of diet drinks was associated with a 36% greater risk for metabolic syndrome and a 67% increased risk for type 2 diabetes (7).

Canola and other seed oils Oils like canola, corn, sunflower, safflower, and soybean are all highly processed and unnatural. They contain omega 6 fatty acids which are pro-inflammatory. As I have mentioned in a previous post that when canola oil undergoes hydrogenation, this increases its level of trans fats. Trans fats are fats that you want to avoid as they increase LDL cholesterol and lower HDL cholesterol. If a fat is partially hydrogenated oil it means that there is some trans fat present. Trans fatty acids are detrimental byproducts of food processing are really bad for health. There is a strong link between trans fats and inflammation and also depression (8). Of interest is that a recent study found that when mice were fed canola oil over 6 weeks they gained weight (although that is in conflict with other studies and may be due to the study duration). Of importance, this study found that canola oil had a detrimental effect on memory, and synaptic integrity in mice with Alzheimer’s Disease (9).

So there we have a few foods that are likely to contribute to depressive symptoms- not heal. Food can be medicine, not only for our body- but also our brain. But it is important to avoid those foods that may produce inflammation and therefore contribute to poor physical and mental health.