In previous articles I have discussed the relationship between food and chronic pain, and the general message is that there are so many different factors and conditions contributing to pain that it is hard to narrow it down specific guidelines. However, recent studies have been looking at the dietary links to chronic pain in a different light. Instead of focussing on the disease or condition that initiated the chronic pain, the focus was on the factors sustaining it within the brain and central nervous system, factors common to all types of chronic pain. In particular, in recent studies the emphasis centred on central nervous system sensitisation.
What is ‘central nervous system sensitisation’ you may ask? Well firstly, it’s not a diagnosis or condition, rather it is a process that frequently occurs in chronic pain. It involves immune driven inflammation within the brain and spinal cord that impacts the behaviour of neurons (nerves). Or to get technical for those of you that want to know (or if not skip to the heading below “What does diet have to do with it?”) central sensitisation is defined as increased responsiveness of particular nerves called nociceptors. These are the nerves that transmit ‘danger’ messages from the periphery (hands, body, feet, organs etc) to the central nervous system (spine and brain).
With central sensitisation, people experience hypersensitivity to noxious sensations (painful stimulus hurts more than it used to), to non-noxious touch (sensations that shouldn’t hurt start to hurt e.g., clothing, movement, normal touch) and the pain response spreads (it hurts all over).
Central sensitisation involved changes in the central nervous system and not necessarily due to processes in the tissues. This process doesn’t occur in isolation and the role of thoughts, feelings, emotions and context all contribute to the experience of pain, as does what is occurring in the physical body however, the outtake is that central sensitisation amplifies input (noxious or otherwise) from the periphery, thus potentially leading to amplified pain responses.
What does diet have to do with it?
A paper by prolific pain researcher Nijs (et al., 2020) suggests that diet can contribute to the induction of central sensitisation, potentially amplifying pain responses. Thus, what we eat can contribute to more or less pain. The theory goes a little bit like this:
- The vagal nerve informs the brain about many dietary factors including food intake, nutritional status and inflammatory responses to food, which can lead to neuro-inflammation within the brain and spinal cord.
- A low fat and low sugar diet can lead to decreases in inflammation and oxidative stress reducing vagal sensing of pro-inflammatory responses and thus ‘danger’ messaging to the central nervous system. In turn, this reduces the induction of central nervous system inflammation, a factor in central sensitisation.
- Some early studies show promise with regard to nutritional interventions playing a role in the inhibition of neuro-inflammation and as such a less central sensitisation.
So, what are the take home points?
- Consume a lower fat diet. This doesn’t mean cutting all fat out (it plays an important role in our health), rather the focus needs to be on reducing total fat intake to approximately 30% of total kilojoule intake. Australians on average eat about 35% total fat intake.
- Reduce red meat intake or choose low fat cuts.
- Of the 30% or less fat intake, choose a predominance of healthy fats including monounsaturates (olive oil, avocado, nuts & seeds) and polyunsaturates (SMASH fish – salmon, mackerel, anchovies, sardines and herrings, as well as chia seeds & flax seeds).
- Increase vegetable intake to at least 5 serves (cups) per day, legumes and whole grain intake, which will provide fibre to bind fats and help eliminate before they are absorbed. These foods will also support a healthy microbiome which the vagus nerve will also sense e.g., all vegetables, rolled oats, brown bread, wholemeal pasta, quinoa, lentils, and beans.
- Eat less sugar. Unlike fat, there isn’t a definite guideline around sugar apart from less is better. If you are experiencing chronic pain, my general recommendation is to allow 3 x treats per week only. Whole fruit is healthy and not included in this restriction.
If you are unsure about these recommendations, I get it, but to push the point a bit more, studies have shown that saturated fat and sugar intake were found to be positively associated with pain intensity and pain threshold (Elma, et al, 2020). That means that those that ate these foods had high pain levels than those who didn’t. Still in doubt, try it for 3 weeks and see how you feel.
Ananda Mahony is a naturopath, nutritionist and works with chronic pain. To read Ananda’s bio and see how she works with those in chronic pain, click here.
Elma, Ö., Yilmaz, S. T., Deliens, T., Coppieters, I., Clarys, P., Nijs, J., & Malfliet, A. (2020). Do nutritional factors interact with chronic musculoskeletal pain? A systematic review. Journal of clinical medicine, 9(3), 702.
Nijs, J., Tumkaya Yilmaz, S., Elma, Ö., Tatta, J., Mullie, P., Vanderweeën, L., … & Van Oudenhove, L. (2020). Nutritional intervention in chronic pain: an innovative way of targeting central nervous system sensitization?. Expert opinion on therapeutic targets, 1-11.