The Guts of Sugar Addiction…

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Easter has come and gone, we have indulged in some much needed R&R, some family time and of course licked every skerrick of raw chocolate egg crumbs off everything we could find. It’s safe to say that indulging in all these things, on special occasions (apart from R&R and family time which should be as frequent as you can!), is not just good for our soul, it is also good for our mental and physical health too. But what about when food indulgences become more of a regular occurrence-we can’t stop at just one and our body screams at us until we fill it to the brim with whatever it may desire? Well, it’s safe to say this isn’t healthy and is tipping the edge of addiction.

Food addiction can be as serious as a drug or alcohol addiction, however it is never acknowledged in the same arena.

Our love for sugar is rooted in brain circuits dedicated to reward the recognition of high-energy food sources [1]—a mechanism essential for animals in the wild, and most certainly critical in our own evolutionary trajectory, however what was once a pathway that ensured human survival is now manipulated and exacerbated by modern day influences that have occurred within our microbiome that is creating an epidemic of sugar addiction.

Because we’re all brain surgeons, we know that different areas of our brain ‘operate’ different aspects of our moods and behaviour. Well deep in the centre of our brain sits ‘the reward pathways’ which can be responsible for driving our feelings of motivation, reward and behaviour [2]. The main goal of the reward pathway is to make us feel good when we engage in activities that enable our survival- eating, drinking and sex.

The most important reward pathway in the brain is the mesolimbic dopamine system, composed of the VTA (ventral tegumental area) and NAc (nucleus accumbens) [3]. When this pathway is triggered by an outside stimulus (for example, sugar), dopamine is released in a flurry which gives you a little jolt of pleasure, a pat on the back let’s say, and it makes you feel ‘good’ for eating that particular food [2]. In addition to making you feel good (for assuring the longevity of humankind), the reward pathway also connects to other areas of the brain that control memory and behaviour, so it also tells the memory centres in the brain to pay particular attention to all features of that rewarding experience, so the behaviour is encouraged again in the future [3].

This particular pathway is also activated with addictive drugs (such as cocaine), obviously drugs of abuse aren’t required to ensure human existence, however they interfere with this pathway by binding to the dopamine transporters, causing a continuous stimulation of the receiving neurons [4]. So sugar, on a biochemical level, is just as addictive to our brains as cocaine.

The reason sugar is such a powerful trigger for this pathway stems down to evolution- all of the food challenges our prehistoric ancestors faced mean that biologically, we are wired to prefer sweet food. The Human Brain is a glucose hungry power-house, so back when we were hunter-gatherer, ape-like Neanderthals, not knowing when our next meal would come- consuming a glucose rich morsel (such as a berry, piece of fruit or some sweet nectar) would cause a trigger in this pathway because it gave our Neanderthal-like cells an instant energy fix…so we were chemically instructed to do it again to ensure constant energy fixes…  unfortunately, broccoli didn’t have the same evolutionary impact!

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The problem today is that we are unknowingly triggering this pathway more often than not because sugar is in everything and not only that, it is available to us in an instant so when we get the urge for our next fix, it is usually hard to resist. The more frequently this pathway is triggered by sugar, the more we are ‘programmed’ to consume it and, the more we eat the more our dopamine receptors ‘adapt’ to the load…basically we need more and more to get the same ‘pat on the back’.

If it isn’t enough battling our prehistoric brain chemicals in the fight against the sweet stuff, we are also up against modern-day lifestyles that nudge these addictions further along. It’s a no brainer that the sugar we mostly consume today is a far cry from the stuff our ape-pals ate. They ate it in its whole form, full of fibre, micro-nutrient dense and sparingly. We eat it processed, refined, nutrient deficient and excessively. Also, it’s not just the sugar itself that has changed, we have too and not in a we-can-now-walk-on-two-legs kind of way.

Today, our gut microbiome is less diverse than our hunter-gatherer fore-fathers [5]. There are several aspects of western lifestyle that have been hypothesised to alter the gut microbiome and decrease diversity- these include, but are not limited to, diet, sanitation, the use of pharmaceutical drugs and the increase in caesarean sections [6].

Microbes, in the gastrointestinal tract, have the ability to manipulate host eating behaviour to increase their own health, sometimes at the expense of host health [7]. They also however, have to compete with other members of the microbiota for habitat and nutrients, so a highly diverse microbiome (similar to what our ancestors had) are more likely to expend energy and resources in competition with each other rather than a less-diverse microbiome (similar to what we now commonly have) which is more likely to have species within in it that have large population sizes and therefore, more resources available for host manipulation [7].

Our diet modifies the microbiome, and the microbiome modifies our diet.

Host manipulation of eating behaviour can occur throughout a variety of mechanisms. The bugs that reside within our guts have direct access to the vagus nerve, which is basically a line of communication between them (and our gut in general) and our brain. You see, our gut bugs have the ability to release communicative factors, such as hormones and neurotransmitters, which are picked up by the vagus nerve and sent to the brain where they have behaviour altering effects. One way our bugs enhance their own survival (to get food in to them that they thrive on) is by influencing our reward system, by synthesising dopamine and serotonin  and encouraging pleasure-seeking behaviour and triggering cravings [7,8,9,10,11]. On the contrast, they can also release toxins and other communicative factors that make us feel bad lowering our mood and making us feel depressed which (as we all know) is another major driver to food addictions and succumbing to cravings [7].

We also have a range of taste receptors within our guts, just like we do on our tongue (gross or ah-mazing??) Our sneaky little critters, if they are dominant enough, can adapt these taste receptors to suit their needs [7].  So, for example, having a higher number of sweet taste receptors will enhance our love of sweet-tasting foods, however we are really only enjoying the taste of these foods because our gut bugs ‘manipulated’ us into doing so.

 

 

So are we destined to be the puppet to these tiny-tyrant puppeteers? Absolutely not! What can we do? We manipulate them back! Of course there are specific species of microflora that are known to drive sugar cravings more so than others, such as Candida, however by increasing your overall diversity in beneficial species such as lactobacillus and bifidobacterium and by increasing fibre and resistant starch in your diet is a good place to start [7]. Our friendly bacteria ferment these carbohydrates into short chain fatty acids (SCFAs) including butyrate and propionate, which changes the way our brains perceive energy-dense foods such as cake and ice cream, so that these foods lose their appeal and we eat less of them [12]. By being able to eat less of the foods, which feed the microbes, which drive the cravings for those foods (confusing much) will see a decrease in these microbes as they are not able to thrive as readily without their primary food source and therefore, they aren’t powerful enough to influence our eating behaviour.

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A nutrient-dense, real food diet, that includes fibre and fermented foods rich in probiotics, is thought to encourage microbial diversity, and diversity is associated with less opportunities for specific species to dominate.

So rather than attributing your cravings to a ‘weakness’ or ‘lack of will power’, acknowledge that this is probably your gut bugs making you want it for their own benefit. Take a few moments to relax and be mindful, or participate in some other dopamine enhancing behaviour such as exercise, to help the craving pass. Or, as we are all human and love eating yummy food – consume sugars that are in their natural state, part of a whole food, micronutrient dense and packed with fibre that will travel all the way to your colon and feed your good guys.

Some simple steps to help beat the microbial driven sugar addiction:

  • Eat less of processed and refined sugary foods
  • Consume fermented foods rich in lactobacillus and bifidobacterium
  • Consume fibre-rich, whole foods that bring with them resistant starch to feed the bifidobacterium and lactobacillus strains
  • When cravings hit participate in dopamine releasing activities such as exercise to get the same biochemical ‘relief’ that sugar would normally bring
  • When you do consume sugars, consume it in its whole, nutrient-dense, full fibre form to reap all the benefits!

 

 

References

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2235907/

[2]. http://learn.genetics.utah.edu/content/addiction/rewardbehavior/

[3]. http://neuroscience.mssm.edu/nestler/nidappg/brainrewardpathways.html

[4] https://www.drugabuse.gov/publications/teaching-packets/understanding-drug-abuse-addiction/section-i/8-cocaine-neurotransmission

[5] http://www.cell.com/cell-reports/fulltext/S2211-1247(16)30099-7

[6]. http://www.cell.com/cell-reports/fulltext/S2211-1247(15)00340-X

[7]. http://onlinelibrary.wiley.com/doi/10.1002/bies.201400071/full

[8]. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3554020

[9] https://www.ncbi.nlm.nih.gov/pubmed/9360553

[10] https://www.ncbi.nlm.nih.gov/pubmed/11051338

[11] https://www.researchgate.net/publication/263705212_Vagal_Pathways_for_Microbiome-Brain-Gut_Axis_Communication

[12] https://www.ncbi.nlm.nih.gov/pubmed/27169834

 
 
2 Responses to "The Guts of Sugar Addiction…"
  1. Anita McKenzie says:

    Who would have thought that gut bugs could be manipulative little suckers!!??
    Such an eye-opening article, Kirsty. It never ceases to amaze me how clever and intricate our bodies are. Thanks once again. I’m learning so much!

  2. Dex says:

    Thank you for this complete and insightful article. It’s filled in a few missing parts of the story for me as I struggle to manage my own gut flora, mood and cravings. It has also given a bit of a boost to my GAPS diet commitment.

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