The quality of the foods you consume may affect much more than just your waistline.
Research shows that certain ingredients, commonly found in fast foods, have the ability to alter brain function.
The connection between diet and brain function occurs through various communication pathways and signalling molecules between the gut and the brain – termed the gut-brain connection (described in an earlier post). This communication has been extensively researched over the last decade with evidence confirming the functional link between the two organs.
Diet, amongst other factors, influences the composition of the gut microbiota, which in turn produces molecules that influence immune function. When the diet is high in processed foods, sugar, saturated fats ad food additives, the microbiota is altered, and this induces inflammation. It is this inflammation that is communicated through gut-brain pathways to produce inflammation in the brain, termed neuroinflammation. (1).
Much of the research has looked at the effects of various food components on the hypothalamus, a key brain region that integrates signals from the body along with those from other parts of the brain in order to regulate metabolism, appetite, hormonal balance and the stress response. It also influences brain regions responsible for sleep patterns, cognitive function, reward-based behaviours, mood and emotional control.
Neuroinflammation has therefore been associated with an increased appetite, cravings, reduced impulse control, impaired cognitive function, a heightened stress response, anxiety, depression and insomnia – to name just a few. (10,11).
This is one of the reasons it’s so hard to resist cravings or make healthy choices – and this just perpetuates the vicious cycle.
Certain fats and refined sugar are high on the list of brain damaging compounds. Here’s what the research has found…
The problem with refined oils
Recent research from the University of California found that the consumption of soybean oil is associated with dysregulation over 100 genes in mice. Many of these alterations have been linked to inflammation and significant changes in the hypothalamus.(4) Researchers also found that some of these epigenetic changes may be involved in the development of neurological disorders such as anxiety, depression, Alzheimer’s, Parkinson’s, autism and altered pain perception (4).
Soybean oil, commonly found in fast foods, is the most widely used oil in America and is also linked to inflammatory and metabolic disorders such as diabetes, insulin resistance, obesity and fatty liver disease. (2,3). Other refined oils, such as canola oil (the most commonly consumed oil in Australia) have also been linked to systemic and brain inflammation in animals. (5).
To eat meat or not?
Since the increasing popularity of diets such as the ketogenic and paleo diets, there is much debate over meat-based versus plant-based diets (see blog here). Over the last few years, it seems that even the most committed proponents of meat-based diets are starting to change their view and there is good reason for this.
Fatty acids are the building blocks of cell membranes and are essential for healthy brain function. If your diet is high in saturated fat (as found in meat), then these fats will make up the majority of the cell membrane and alter the function of the cell. They will also increase inflammation in the body and brain.
Animal-derived saturated fats are considered to be signalling molecules of inflammation – regardless of the quality of the meat. This inflammatory role has long been associated with cardiovascular disease and more recently with a number of disturbances such as dysbiosis, leaky gut, chronic inflammation, metabolic disorders and neuroinflammation. (10,11).
The quality of the meat will determine factors such as the presence of hormones, additives and antibiotics, but the problem of pro-inflammatory saturated fats remains - regardless of its source.
A diet high in plant-based foods is preferable for optimal health, but that does not mean that all animal products need to be avoided. Vegan or vegetarian diets often lead to nutrient deficiencies and this itself may have a negative impact on brain health. It is best to seek professional advice should you decide to follow a 100% plant-based diet.
The danger of sugar…
Refined sugar – in any form – alters the gut microbiota and causes large and rapid spikes in blood glucose levels. This can have destabilising effects on immune function, metabolism, hormones and brain function. The severity of these consequences will depend on how effectively an individual clears glucose from the blood stream – this is termed glycaemic control. Those with poor glycaemic control are more likely to experience prolonged elevated glucose levels that induce inflammation, metabolic and hormonal imbalances as well as altered brain function. As a result, these individuals may experience mood swings, brain fog, fluid retention and/or cravings within hours of consuming a meal containing a level of carbohydrates that exceeds their individual tolerance level. (12, 13).
Another factor to consider when it comes to the effects of sugar on the brain is that glucose activates reward centres to produce a sensation of euphoria, similar to that initiated by any substance of addiction. In fact, mice studies have shown that sugar may be more addictive than cocaine (14). In addition, the combination of fats, sugar and salt, in certain proportions – for example, as found in a burger or cheesecake– has the greatest potential for addiction. In the process of manufacturing foods, companies find the specific combination of these ingredients to produce the greatest state of euphoria. This combination has been termed the “bliss point” and ensures that you keep coming back for more!(15)
What’s healthy for brain function?
Our bodies have an enormous potential to regenerate and heal given the right internal environment. In order for the brain to be healthy, all processes in the body must be optimised.
Given that inflammation is the main driver of most chronic conditions and symptoms, reducing inflammation and improving immune function is the key. The best way to reduce inflammation is to start with a healthy, clean and unprocessed diet.
Firstly, you will need to avoid processed foods, food additives and foods that are high in sugars of any form (and that includes coconut sugar and dates!). If you couldn’t imagine life without bread, cheese, coffee, wine, chocolate….(or whatever comes to mind…), then your brain has been hijacked by these addictive foods and it’s time to let them go – at least for a while. Once you’ve corrected the underlying gut dysfunction, inflammation, metabolic, hormonal and neurological disturbances, you may be able to have a treat every now and then without triggering the addiction cycle.
Secondly, be honest with yourself about how many and what types of carbohydrates your body and brain can handle. If you experience cravings, fluid retention, rapid weight gain, mood swings and brain fog after eating certain carbs, then it’s very likely that your body isn’t tolerating them all that well. You need to find the level of intake that works for you and again, this will change as your body becomes healthier.
Finally, reduce your intake of red meat and add in some healthy fats. Unsaturated fats help to reduce inflammation and improve cell function. Omega-3 fatty acids have long been known for their potent anti-inflammatory effects, and olive oil and flaxseed oil have recently been found to reduce inflammation in the hypothalamus in mice (7, 8). Unsaturated fats are found in olive oil, flaxseeds or flaxseed oil, fatty fish (such as salmon and mackerel), avocados and avocado oil.
If you would like a more formal program to reverse some of the damage, the Biome Protocol is based on the principles of nutritional medicine and incorporates scientifically researched nutrients and dietary techniques to help bring the body back into balance.
1. Zhu, S., Jiang, Y., Xu, K. et al. The progress of gut microbiome research related to brain disorders. J Neuroinflammation 17, 25 (2020). https://doi.org/10.1186/s12974-020-1705-z
5. J Agric Food Chem. 2018 Jul 11;66(27):7172-7180. doi: 10.1021/acs.jafc.8b01836. Epub 2018 Jun 29.
7. Atherosclerosis. 2009 Aug;205(2):458-65. doi: 10.1016/j.atherosclerosis.2009.03.009. Epub 2009 Mar 19.
8. Curr Atheroscler Rep. 2004 Nov;6(6):461-7.
9. PLoS One. 2012;7(1):e30571. doi: 10.1371/journal.pone.0030571. Epub 2012 Jan 18.
10. Fritsche KL. The science of fatty acids and inflammation. Adv Nutr. 2015;6(3):293S‐301S. Published 2015 May 15. doi:10.3945/an.114.006940
11. Melo HM, Santos LE, Ferreira ST. Diet-Derived Fatty Acids, Brain Inflammation, and Mental Health. Front Neurosci. 2019;13:265. Published 2019 Mar 26. doi:10.3389/fnins.2019.00265
13. Diabet Med. 2013 Sep;30(9):1080-6. doi: 10.1111/dme.12209. Epub 2013 May 14
15. Rao, P., Rodriguez, R.L. & Shoemaker, S.P. Addressing the sugar, salt, and fat issue the science of food way. npj Sci Food 2, 12 (2018). https://doi.org/10.1038/s41538-018-0020-x