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By Andrea Cannas


September 27, 2023


The brain fuel factor: why you are not just what you eat

We are what our bodies do with what we eat.

Why are your symptoms persisting even after you implement healthy changes? Is it really only about how we act or behave, for example, how many veggies we eat or how long we exercise for?

The reality is that our health and lifespan are not inherently determined by what food groups we avoid or what specific foods we put in our bodies. Indeed, there are many other factors that finetune our health and lifespan.

One of these factors, follows the Biopsychosocial model which focuses on the integrated functioning of our body systems. How many times do you evaluate your experience to an action or behaviour? For instance, have you ever asked yourself how well you digested your meal, why you feel wired and tired at night or why you have painful menstrual cramps?

Which key processes may offset the health benefits of any diet if they don’t function optimally?

  1. Incomplete digestion

What is digestion?

Digestion is the process that describes the breakdown of food into nutrients and energy for our bodies to function and begins as soon as we smell food. In brief, to assist with the entire digestive process of macro-nutrients and micronutrients, we produce a digestive mix of oral digestive enzymes, stomach acid, bile and pancreatic juices.

As we age, there is a gradual decline in stomach acid, so older adults tend to require further support in this area. In addition, there are many other factors that can interfere with the digestive process. These include: 

  • lack of sleep,
  • chronic stress and psychological factors,
  • overeating,
  • medications (for example, painkillers or antibiotics),
  • alcohol,
  • overexercising,
  • medical conditions such as hypothyroidism
  • infections
Any other lifestyle factors that can affect our body’s innate digestive aid and ability to break down food?
  • eating on the run to work
  • chewing your food in front of your computer
  • chewing gum frequently
  • having coffee or drinks with your meals

Food indigestion often co-occurs with other symptoms such as bloating, nausea, heartburn, food sensitivities and gastrointestinal distress. Moreover, if these symptoms are sustained for a long time, significant irritation can happen to the gut barrier. As a result of this, the gut barrier can become more permeable, perpetuating inflammation and a heightened sensitivity to infections.

     2. Absorption

What do we mean by absorption?

How well a nutrient from a food is absorbed by our body, referred as its bioavailability, is something that has been heavily discussed in research.

By increasing the surface area of food eaten through digestion we maximise the chances for key nutrients to be optimally absorbed in the small intestine and for other molecules to pass through the bloodstream and to be filtered for excretion or re-absorption by the liver. Moreover, our gut microbiota – the bacteria that live in our digestive system, also assist with digestion and nutrient absorption.

Nutrient absorption varies across people at different life stages and with different health requirements. Furthermore, the therapeutic effects of a single nutrient can be limited by:

a) how foods are prepared and cooked, b) how the nutrient is formulated and packaged (i.e. the quality of your supplement), c) what the food or nutrient is paired with, and d) how well it is digested and metabolised.

How is my brain function affected if I don’t break down & absorb my food well enough?

Our gut is now referred to as “our second brain” due to its well-renowned role in producing hormones and neurochemicals that influence brain function and digestion. You can read more about this in my other blog.

In brief, indigestion can lead to large undigested food particles fermenting in the small intestine. This can create a favourable environment for unfriendly gut bacteria to grow. As a result of this, an overgrowth of potentially pathogenic bacterial strains can interfere with the absorption of key nutrients some of which include B vitamins. B vitamins are key key for nerve signaling, energy production, mood regulation and memory.

3. Elimination

Our body largely relies on the liver to metabolise foods, chemicals and hormones to either absorb, recycle or remove potentially dangerous toxins. This process is important as improper clearance of environmental toxins in human tissues can result in illness and dysfunction in the immune and endocrine systems. Indeed, studies have confirmed that liver dysfunction is directly associated with chronic disease such as obesity, cardiovascular disease including neurocognitive and reproductive concerns.


In conclusion, my take is that the benefits of a healthy diet can be optimised under conditions of effective digestion, intestinal absorption and liver elimination. Some groups of vulnerable patients may require professional therapeutic support and should seek the advice of a qualified nutrition practitioner.



No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

  1. Food Forum; Food and Nutrition Board; Institute of Medicine. Relationships Among the Brain, the Digestive System, and Eating Behavior: Workshop Summary. Washington (DC): National Academies Press (US); 2015 Feb 27. 2, Interaction Between the Brain and the Digestive System. Available from:


  3. Appleton J. The Gut-Brain Axis: Influence of Microbiota on Mood and Mental Health. Integr Med (Encinitas). 2018 Aug;17(4):28-32. PMID: 31043907; PMCID: PMC6469458.


  5. Panda C, Komarnytsky S, Fleming MN, Marsh C, Barron K, Le Brun-Blashka S, Metzger B. (2023) Guided Metabolic Detoxification Program Supports Phase II Detoxification Enzymes and Antioxidant Balance in Healthy Participants. Nutrients.15(9):2209. doi: 10.3390/nu15092209. PMID: 37432335; PMCID: PMC10181083.



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