Sugar: The Body’s Response And The Gut Microbiome Episode 1: Glucose


Sneaky Peek

Sugar is made of glucose and fructose. Our body deals with these two substances in very different ways. Our body’s main source of energy is glucose. We need it but we are eating way too much of the stuff. Glucose is not only found in sugar but in a wide range of other foodstuffs. In natural foods, glucose is mainly accompanied by fibre. Which is good. In highly processed foods, the fibre is lacking. Which is bad. Over-consumption of glucose is partly to blame for the massive increase in type 2 diabetes and the health issues that come with it. High insulin levels related to diabetes, cause another whole layer of issues through inflammation and upsetting our hunger hormones. And we mustn’t forget our microbes. High glucose/fructose diets disrupt these guys too which can exacerbate our health problems. Read on for more detail.


I have found this topic so interesting, it has turned into a 3 part series rather than a one off! This episode will deal with glucose, the second will cover fructose and the third will cover the “Pleasure Trap”. A joyous trilogy if ever there was one.

In the newspaper last week, it stated that 92% of women and 80% of men in their fifties and sixties have dangerously large waists putting them at significant risk of heart disease and diabetes. Death from type 2 diabetes in 50-70 year olds has risen by 97% in men and 57% in women since 1990. These are staggering statistics. The frustrating thing for me, is that the newspaper stated lack of exercise as a significant factor. Yes, exercise is important to health but what we eat (or stop eating) has far more influence on diabetes. We need to take an honest look at our glucose and fructose intake.

There is no shortage of information available about how bad sugar is for us. But what do we mean by “sugar”? To me, this clarification is of fundamental importance. Sugar, itself – the white stuff, is a carbohydrate made of glucose and fructose. I fear that focussing on sugar, alone, is causing us to ignore the bigger picture. The simple carbohydrates glucose and fructose are the basic components of many, many more foodstuffs than just sugar.


Glucose, Insulin, Insulin Resistance and Inflammation

Most carbohydrates (be they in the form of sugar or potato or pasta or pastry) are broken down to glucose and fructose by the body. Glucose and fructose’ metabolic pathways differ but when we talk of blood “sugar” levels, we really mean blood “glucose” levels. Fructose will get its 15 minutes of fame next episode.

Glucose – the energy of life – is the energy our cells use. In the unlikely event (in the Western world) that I don’t eat enough of it, my body synthesises it. When my body makes glucose, it does so mainly in the liver. Glucose is utilised by all organs in my body. My body needs to keep my blood “glucose” levels constant – generally at around FIVE grams of glucose in my entire bloodstream at any one time (that is 1 teaspoon).

We can only safely metabolise around 6 teaspoons of added “glucose” a day. Our average consumption nowadays is around TWENTY teaspoons per day. Excess glucose is turned into glycogen by the liver and muscles and stored. When glycogen stores are full, it is turned to body fat. Insulin is the hormone transporter which passes glucose from our food into our cells for energy. Healthy cells have lots of insulin receptors, so they respond well to insulin and energy is passed into these cells easily.

If we are consume foods that convert quickly to glucose (refined carbohydrates), we get a blood “glucose” spike. Insulin is produced, blood glucose levels plummet and we seek out more glucose food sources – a vicious cycle (see episode 3). Insulin encourages cellular growth. It promotes fat formation and retention. Persistently high levels of insulin affect other hormones – upsetting hunger and satiety hormonal balance generally.

When cells are exposed to lots of insulin over time because the blood is awash with glucose, the cells adapt to prevent glucose overload. They reduce their number of insulin receptors. This is insulin resistance. I keep eating refined carbohydrates, I have too much glucose in my blood. My insulin is trying to transport it out of my blood and into my cells. My cells are saying NO ROOM AT THE INN. The result – excess blood glucose. The response – the pancreas produces even more insulin to try to reduce the level of blood glucose. Over time, the more insulin in my blood, the more insulin resistant my cells become. The more insulin resistant my cells become, the more glucose in my blood. And round we go again. Until the pancreas gives up the ghost and I develop Type 2 Diabetes. And in the meantime, the excess glucose in my blood causes inflammation.

Excess glucose in the blood is very damaging. It affects the brain by depleting neurotransmitters, B vitamins (which are needed to make neurotransmitters) and magnesium levels (affects your liver and nervous system). Diabetes is a leading cause of early death – it causes heart disease, stroke, blindness, amputation, neurological disorders and Alzheimer’s if left untreated. I can think of better ways to go.

High blood glucose also causes the formation of deformed molecules called AGES. The body does not recognise AGES, so it initiates an immune reaction – inflammation. This has many negative effects on the gut (find out more about Inflammation - The Source Of Most Woes) but these structures also contribute to the degeneration of the brain and its functioning. People with diabetes are at least twice as likely to develop Alzheimer’s and around 80% of people with Alzheimer’s also have some form of diabetes or disturbed glucose metabolism.

Is the solution to inject more insulin? No, the solution, surely, is to CONSUME LESS GLUCOSE.


Refined Versus Unrefined Carbohydrates And The Impact On Gut Microbes

Refined carbohydrates – sugar, high fructose corn syrup (HFCS) (a cheap glucose/fructose mix used in a mind-boggling array of foodstuffs) white rice, white pasta, white bread, pastries, cakes, biscuits – have been detached from their natural fibre during processing and their effect on my system is this – they are digested into their basic glucose and fructose components in my small intestine and absorbed rapidly into my bloodstream. When I am consuming excess of it, I cannot absorb it all in my small intestine so some of it gets through to my large intestine (colon). This excess glucose causes some of my normal healthy gut microbes to be replaced by unhealthy species of microbes. High glucose/fructose diets have been shown in animals to disrupt the balance of gut microbes, encouraging pathogenic bacteria and species of bacteria that thrive on more glucose. These microbes send out new messages that start to alter my hormonal signals managing hunger and satiety and call to my brain for more glucose. In addition, these foods lack fibre. Nothing nourishing makes its way down to the microbes residing in my large intestine. No decent meal for the tribe. If I persistently fail to feed them fibre, I start to upset the ratio of helpful microbes to not so helpful microbes.


Unrefined complex carbohydrates are different to refined carbohydrates

Beans, greens, brown rice, vegetables, legumes, whole grains also break down to glucose (and fructose) but they contain fibre which slows the rate of glucose/fructose release into our bloodstream thereby prompting a less extreme insulin response. Which results in less inflammation in the long term. Importantly, fibre from these foods also survives into the colon to provide soluble fibre for my microbial tribe to feed on. They also provide insoluble fibre, which can’t be absorbed by my body but helps to bulk out my poo and keep my colon healthy. These foodstuffs also contain all sorts of nutrients that my body needs. Soluble fibre is fermented by my gut bacteria. It encourages helpful bacteria to proliferate and, as they ferment, they produce short-chain fatty acids, some of which are used as energy by the cells of our body as well as for maintenance and growth of our microbes.


Blood glucose and microbes

Blood glucose levels reflect not just dietary carbohydrate consumption but also the balance of bacteria in the gut. A study from The University of Amsterdam has improved blood sugar issues and reduced insulin resistance in more than 250 diabetic people using fecal transplantation from healthy lean non-diabetics. Certain species of gut bacteria help control blood sugar levels. This sort of research is starting to show us that not only should we be thinking about the direct consequences of a diet high in refined carbohydrates in terms of high blood glucose levels, insulin resistance and inflammation, but we should also be thinking in terms of the role our gut bacteria play in this process and the impact what we eat has on which bacteria proliferate. They influence our metabolism, the way we store fat, levels of glucose, they express genes that relate to metabolism and respond to hormones that make us feel hungry or full. What we eat influences whether they do this to support good health or to hijack it.


Increase our intake of naturally occurring whole foods – vegetables of all types.  Whilst they contain glucose, they also contain fibre and many nutrients our body needs. And they feed our beneficial bacteria. Which then feed us.

Reduce our intake of refined, highly processed foods – cakes, biscuits, white rice, white pasta, white bread, pastries…. they give us more glucose than we can cope with and do not benefit us in terms of nutritional content.


Spreading straightforward information about the fundamental importance of a healthy gut microbiome.