Sugar is not just an empty calorie that makes you gain weight. Refined sugar and high fructose corn syrup are, together with the pesticides on our food, among the biggest silent underminers of our health. They disrupt something far more fundamental than your weight: your blood sugar. And that single system touches almost everything, from your energy and your mood to your immune system and your gut.
In this article you'll read how refined sugar disrupts your blood sugar and what that does to your body, how sugar disturbs your gut bacteria and can contribute to a bacterial overgrowth in your small intestine (SIBO), and why it ultimately leaves your immune system and your whole body struggling.
Where the problem begins
Not all sugar is equal. The biggest problem for your health are the refined, factory-made sugars: things like (granulated) sugar and glucose-fructose syrup. After that come the naturally occurring sugars in fruit juice. Fruit juice sounds healthy, but there are two caveats. The first starts with the question of whether the juice is made from real fruit, or mostly from sugar and flavourings. The second is that with fruit juice you only drink the juice, so you get a hit of sugar.
The key difference between fruit juice and a whole piece of fruit is that the fibre in fruit slows down absorption, which flattens the sugar spike in your blood.
So it isn't about the word "sugar", but about its effect in your body: the spike and the swing in your blood sugar. And it's precisely that swing that lies beneath a surprisingly large number of health complaints.
Your blood sugar: a tightly guarded system
Your brain depends on glucose, delivered through your blood, for its energy. You don't need to eat glucose for this: your body makes it itself through a process called gluconeogenesis. So you don't need sugar for it.
What does matter is that your blood sugar stays within a narrow range. Your brain only works optimally between certain values. Both too high and too low disrupt its functioning and pose a danger. That's why this system is heavily regulated, with two opposing dials: if you have too much sugar in your blood, insulin enters your bloodstream and brings the sugar down. If you have too little blood sugar, gluconeogenesis kicks in and your liver makes glucose. As long as that balance runs smoothly, you don't notice a thing. The problem arises when you load the system day in, day out.
What processed food does to it
Through refined sugars and fast carbohydrates you constantly take in too much sugar, which sends your blood sugar shooting up. Insulin can absorb that for a while, but if it constantly has to step in, the system gets exhausted and your cells eventually respond less well to insulin. That's called insulin resistance, a key step towards type 2 diabetes and many other problems.
And then there's the daily rollercoaster. A quick peak is followed by an equally quick drop, often below your starting level. Those swings can leave you with a restless mind with thoughts that won't switch off, a heavy energy dip, and more frequent hunger and cravings, so you eat more and gain weight.
You may also recognise it in never quite feeling stable in your energy. You go up and down. You're not calm in your thinking, you find it hard to concentrate, and you're sometimes angry, wired or withdrawn for no real reason.
This comes from the blood-sugar rollercoaster, with your brain sitting in the cart.
Sugar and your gut bacteria
Besides affecting how your brain works, a sugar-rich diet can also affect your gut. In your large intestine lives an enormous community of bacteria called your gut flora. This ecosystem is made up of all sorts of different bacteria that together make sure the processes in your gut run well.
You can picture it as a remote village that governs itself: as long as every task gets done, the village thrives and unwanted guests get no room within the community.
Sugar disrupts this symbiosis. Sugars are the best fuel for the wrong bacteria, giving them the chance to grow out of proportion, with a bacterial overgrowth as the result.
If, on top of a sugar-rich diet, you also eat little vegetables and fruit, the problem grows bigger still. Your gut flora badly needs that fibre to support its work. The most important are the butyrate-producing bacteria. They turn fibre into butyrate, a hugely important short-chain fatty acid. It's the fuel for your gut wall, it helps keep your gut flora strong in species and number, and it has an anti-inflammatory effect, which is extra important for people with Crohn's disease or ulcerative colitis.
When the overgrowth climbs into your small intestine: SIBO
In your small intestine only a few bacteria belong: it's meant to digest and absorb your food. When there is SIBO (small intestinal bacterial overgrowth), bacteria from the large intestine have moved up and are growing in the small intestine in numbers that don't belong there. A sugar- and starch-rich diet and a disturbed large intestine feed that overgrowth, while factors such as slow gut motility (the natural cleansing wave) or too little stomach acid give the bacteria the chance to climb up.
Once the bacteria have moved into your small intestine, they get their sugar-rich meal exactly where you should be absorbing your food.
This means, first, that you can absorb fewer nutrients, because the bacteria eat before you can. But also that they ferment the sugars on the spot, releasing hydrogen and methane.
That's why SIBO symptoms often start within half an hour to an hour after eating. You feel it as a bloated belly, pressure, cramps and wind, often right after sweet or starchy meals. The fermentation products draw in fluid and speed up the passage, so you absorb your food less well and your stools become looser, or in some people cause constipation instead.
And there's a deeper danger. At the junction of the small and large intestine, around the last stretch of small intestine (the ileum), those bacteria come into contact with tissue where they don't belong. That can trigger an inflammatory reaction. And the ileum happens to be exactly the place where Crohn's disease most often shows up. Bacteria in the wrong place, an overburdened immune system and a damaged gut wall together form a breeding ground for chronic inflammation.
The leaky gut and your immune system
Less butyrate means less fuel for your gut wall and a thinner protective mucus layer (the mucosa). When that buffer thins, your gut wall becomes damaged and permeable. This is also called a hyperpermeable gut, or leaky gut.
Substances that normally never cross your gut wall, such as fragments of bacteria (LPS) and not fully digested food particles, leak through. Your immune system springs into action, at first silently, without you noticing anything. But if this situation persists, low-grade inflammation develops, and it can even deteriorate further into chronic inflammation.
The role of your immune system: in a healthy situation, secretory IgA is the calm border guard. It keeps bacteria at a distance and helps you tolerate ordinary food. But when your gut leaks and food proteins enter the body, the response shifts to food-specific IgG antibodies. Scientific research shows this clearly for Crohn's disease: raised IgG against everyday foods such as milk, wheat, egg and soy. In our practice we see these reactions, through a food intolerance test, in people with gut complaints, irritable bowel syndrome and ulcerative colitis too.
And here's the interesting part: if you avoid these foods, so your immune system is no longer exposed to them, those antibodies drop again. So there is a correlation between exposure and reaction.
Why it doesn't stay in your gut
The leaky gut, the immune activity and the swinging blood sugar together send signals through your whole body. You can notice this in:
- Fatigue and a lack of energy from reduced absorption, the blood-sugar swings and an active immune system.
- Low mood. About 95% of your serotonin is made in your gut under the influence of your microbiome. If that balance is disturbed, you can produce less serotonin. And when inflammation develops in your gut through food intolerances or a disrupted gut flora, inflammatory substances such as IL-6 can contribute to low mood and a foggy feeling in your head.
- Low concentration and memory. The blood-sugar swings themselves directly affect your concentration and your mood.
- Your immune system. High, swinging blood sugar has been shown to suppress your innate immune system, leaving you ill more often and for longer. Together with a weaker mucosal defence you react more strongly, making you vulnerable to developing more food intolerances, but also more sensitive to hay fever, allergies and inflammatory complaints, from which all sorts of conditions can arise.
- Your metabolism, liver and more. Insulin resistance and low-grade inflammation are the engine behind many lifestyle diseases: obesity, type 2 diabetes, fatty liver and joint inflammation such as rheumatism. The make-up of your gut flora is closely tied to this. Sugar plays a part in cancer too: tumour cells are extreme sugar consumers, so recognisably that doctors use it to detect cancer, because on a PET scan tumour tissue lights up as it greedily takes up the administered sugar. And an environment with chronically high blood sugar and insulin acts as a growth signal on top of that.
The vicious circle
After a sugar peak your body has to work hard to bring your blood sugar down. As a result your blood sugar drops, followed by a dip that screams for more sugar again. Sugar feeds the wrong bacteria and drives your blood sugar up, that dip and those bacteria strengthen your cravings, and if you can't resist them, even more sugar comes in. It feels like a lack of discipline, but just like with smoking, it's your own body asking for the next hit.
The good news: you can turn it around
The bacteria in your gut and your blood-sugar level move with what you eat and drink each day. You have a say in this yourself. But keep in mind that sugar has a strongly addictive effect on the body.
You can reduce your sugar intake in two ways. Which works best differs per person, and in every case reducing your sugar intake matters greatly for your health. For some people it works to lower their daily sugar intake step by step. For others it works better to change course at once and not touch sugar at all.
Keep in mind that your body can ask for sugar, that it can scream, and that it's up to you to resist that scream. The real, physical craving for sugar is usually fiercest in the first three to five days, and largely gone after about two weeks. After that it's mostly habit pulling you back. It can help to replace sugary products with a sugar-free version, so you lower your sugar intake.
But in all honesty: the very best thing for your body is to leave both the sugary and the sugar-free version alone. Your body works best on real, whole food.
- Choose real fruit over fruit juice, so the fibre flattens the sugar spike.
- Go for a plate of vegetables and a good protein source such as beef, chicken, cod or salmon.
- If you eat little vegetables now, build up the fibre gently so your digestion and gut bacteria can get used to it. And steam them first, so they're easier to digest.
When more is needed
If you have SIBO, or a parasite, fungus or bacterial overgrowth in your gut, that rarely recovers on a change of food alone. In that case a targeted approach is needed. With a SIBO breath test and/or a stool test we can investigate the cause of your symptoms.
This information forms the basis of our guidance. In it you'll discover the real cause of your symptoms and the steps you need to take to reclaim your health. Want to know what we can do for you? Schedule a free 30-minute call. In that conversation I'll ask what you've tried so far and where you stand right now, and I'll tell you what we can do for you. One thing I can promise: you'll leave that call knowing more about your situation.