Sugar and the microbiome

The gut microbiome. You’ve probably heard of it. It is the community of trillions of microbiota (also called microbes or microorganisms) residing in the intestinal tract, their genes, and the products they produce. The microbes coexist with us so we can function. Amazing. 

The composition of different bug populations residing in the gut can change depending on what we eat and drink, the medications we take, if we exercise, and more. Researchers are only scratching the surface in understanding the many roles these microbes play, but we are learning that what populations thrive, are kept in check, or die influences our overall health.

Wonderfully, it is within our power to support the health of the intestinal microbiome and our overall health with the choices we make each day! What you eat is particularly important, including limiting added and free sugars.

Sugar and the microbiome

The microbes in our gut can interact with the immune system to help defend and protect the body. Specific populations create a barrier to stop damaging substances travelling along the digestive tract from moving between the outside world and our bloodstream.

In an editorial published in Nutrients, researcher Reeta Satokari discusses sugar intake and the impact on microbial populations and their ability to produce and maintain this defensive barrier. She states, “A high sugar intake may stagger the balance of microbiota to have increased pro-inflammatory properties and decreased the capacity to regulate epithelial integrity and mucosal immunity.” 

Essentially, a high intake of added sugar and the ultra-processed foods they come in – typical of the Western diet – compromises beneficial populations of the microbiome, leaving us vulnerable to harmful substances that we are exposed to. Our gut lining is thin, and without the protective mucosal layer produced by beneficial microbes in the gut, stuff can seep into the bloodstream we don’t want there. This leads to inflammation.

A Western-style dietary pattern also displaces whole foods in the diet, the real, whole foods that contain necessary nutrients, such as fibre, that the beneficial bugs in the gut love to eat and need to thrive. 

Combined, we risk leaky gut, increased chronic inflammation, and all kinds of health concerns.

“Fiber is perhaps the single most important nutrient for health, because it protects the liver and feeds the gut. Yet it’s the nutrient you don’t absorb because the fibre isn’t for you, it’s for your gut bacteria. You have to consume it to make them happy. You’re not eating for two-but for a hundred trillion.” – Dr Robert Lustig.

Cravings and the microbiome

As mentioned above, what we eat influences what types of bugs are kept in check, thrive, or die. And it’s a two-way street. As part of their survival strategy, via the gut-brain axis microbes in the gut can influence what we “choose” to eat, increasing our desire for certain nutrients or foods. 

It has been found that ultra-processed and junk foods – and ingredients such as added sugars and artificial sweeteners – have been found to alter microbial composition in the gut. This can increase the number of unhelpful microbes, risking poorer health outcomes for the host (i.e. us).

Unfortunately, the more we eat these foods, the more the unhelpful microbes flourish and increase our desire for certain foods. As a result, we find ourselves in a vicious loop of cravings.

What’s more, free sugars can alter gut bug populations and feed species of microbes that lead to degradation of the mucosal lining of the intestine, making us more vulnerable to external pathogens and toxins, and inflammation. In early life, an unhealthy Western-style eating pattern, including regular and excessive free sugar consumption, could impact memory function in adulthood via alterations to the gut microbiome. 

Free sugars don’t only serve as a nutrient for certain gut bugs. A study out of Yale University found that high consumption of glucose and fructose can silence a key protein required for colonisation by beneficial gut bugs associated with lean and healthy individuals. 

The good news is that by eating more whole foods that beneficial microbes prefer – particularly, a variety of fibre-rich foods – the opposite can happen. Beneficial microbes populations increase and predominate over the less helpful species. By increasing your intake of nourishing whole foods, your whole body benefits, you inadvertently leave less room in your daily diet for the unhelpful foods and begin to break the cycle of desire for the sweet stuff.

Diet and the microbiome

In a study published in early 2021, researchers established that beneficial species of the microbiome associated with healthy dietary habits overlapped with favourable cardiovascular and metabolic health markers. 

They shared that individuals who consume mostly a variety of whole or minimally processed foods were more likely to have beneficial bugs in their gut; those consuming more processed foods, including white bread, refined grains, processed meats, and sweetened drinks and juices tended to have microbes attributed to poorer health outcomes. (Check out this article for more.)

The bottom line is, the diet has a significant influence on the microbiome and every choice you make can make a difference. For better health, though it sounds kind of obvious, quality matters.

Let’s keep this simple: here are things to consider eating and limiting for your gut microbiome:

Enjoy

• Quality, whole foods. Eat mostly whole and minimally processed foods. Organic, if possible. 
• Variety. Enjoy a diversity of whole and minimally processed foods to encourage diversity of species in the microbiome, associated with greater resilience and better health outcomes.
• Fibre-rich foods. Processed and packaged foods, and the Western-style dietary pattern, are critically lacking in this important nutrient. Eat a diverse range of foods containing fibre, including prebiotic fibres, such as beans, legumes, some veg, and oats, and resistant starch, such as unripe bananas, plantains, and cooked and cooled rice, legumes, or potatoes. 
• Anti-inflammatory nutrients. Include each day sources of nutrients that help temper inflammation. Think wild-caught fish, such as sardines; chia and freshly ground flaxseeds; dark leafy greens; berries; and herbs and spices, such as rosemary, parsley, ginger, and turmeric.
• Fermented foods. Eat daily to help reduce inflammation and get a dose of beneficial probiotics. Choose high-quality, naturally fermented options, such as plain yoghurt, kimchi, tempeh, miso, and sauerkraut. 

Limit

• Ultra-processed, highly refined foods
• Added and free sugars
• Intense, artificial sweeteners
• Modified or artificial ingredients, including cheap oils, colours, sweeteners, flavours, and the like.

Lifestyle and the microbiome

Food isn’t the only thing to consider when looking after your gut. 

• Exercise. Moving the body is necessary for optimal health. The microbiome may be implicated and in theory, linked to exercise-induced changes that modulate inflammation.
• Manage stress. The gut and the nervous system are linked, plus managing stress can benefit every aspect of your health. 
• Fresh air, in nature. What we breathe can alter the composition of the gut microbiota, for better or for worse. Spend time in gardens, forests, beaches, or anywhere in nature as regularly as possible. 
• Sleep. Aim for 7-8 hours of quality sleep, switching off from screens at least an hour before bed, allowing your body to properly rest and restore.
• Medications. Various medications impact the populations of your gut. Antibiotics in particular are well known for their effect, so if prescribed, be sure to chat with your healthcare provider about taking probiotics during or following treatment to counter adverse effects.

The microbiome influences our health, including (but not limited to) digestive, immune, heart, metabolic, and mental health. The power of a healthy gut can be with you. And a healthy gut can mean a healthy you.

Angela Johnson (BHSc Nut Med)