Why your sugar and carb addiction may (partly) be to blame for your gut and mental health issues, high blood pressure and more

Mirthe Precision Health
12 min readApr 24, 2023

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Chronic high sugar intake has long been recognized as a risk factor for many diseases, including obesity, cardiovascular disease, metabolic syndrome, and type 2 diabetes (R).

But even long before, acute blood sugar spikes from your daily toasty with jam, or mid afternoon chocolate bar, can inflict damage on the body, even if you are seemingly healthy and slim.

Top 9 worst effects of blood sugar spikes:

Chronic inflammation and increased risk of brain and mental health issues

High levels of blood glucose have been shown to upregulate certain immune cells, causing inflammation.

Research indicates that dietary sugars and mixed processed foods may be a key factor leading to the occurrence and aggravation of inflammation (R).

Chronic neuroinflammation (via activation of microglia and astrocytes, important cells in the brain) contributes to nerve cell loss and disease progression in Alzheimer’s disease.

Recent research has identified high blood glucose (hyperglycemia) and the phenomenon of insulin resistance as two of the major factors contributing to an increased risk of Alzheimer’s disease. Alzheimer’s disease has even been nicknamed as ‘type 3 diabetes’, due to its high correlation with blood sugar swings and insulin resistance (R).

In research done by Bukhari and his colleagues, they found that mothers’ high-fructose diets influenced neonatal immunity and altered anxiety behavior and inflammation in adolescence and adulthood. The study suggests that maternal diet may alter peripheral inflammation in newborns, which in turn affects anxiety-like behavior and peripheral inflammation during adolescence. These findings reveal the lasting effects of a mother’s diet on her offspring’s immune system, meaning that the mother’s diet is crucial for their child (R).

2. Lowered immune system function, increased infection and cancer risk

While chronic inflammation is an overtly upregulated immune system, blood sugar spikes have also been shown to at the same time render other immune cells less efficient, thereby tampering with our immune system’s response to invaders such as bacteria and viral infections.

Worse yet, this reduced ‘immune surveillance’ also slows its response to tumor cells, allowing a process termed’ tumor immune escape’.

Recently, it was demonstrated that excessive consumption of high fructose corn syrup is associated with colon cancer development. In the study, mice fed with high fructose corn syrup had significantly increased tumor size (R, R, R, R).

3. A shift in the immune system towards autoimmunity

Common autoimmune diseases include rheumathoid arthritis, multiple sclerosis, psoriasis, hashimoto’s and inflammatory bowel disease (IBD).

In recent years, numerous studies have shown that sugar-sweetened beverages play a key role in the pathogenesis of autoimmune conditions and a shift of the immune system towards the autoimmune favouring Th17 response.

High consumption of glucose, fructose, and sugar-sweetened beverages is also known to reduce the beneficial flora in the gut and increase autoimmune triggering bacteria, such as Prevotella.

It has further been found that high-glucose and high-sucrose diets can aggravate the disease progression of experimental autoimmune encephalomyelitis (EAE) in a disease model of Multiple Sclerosis (R).

4. Impaired gut health & microbiome

As just mentioned, high sugar consumption is known to reduce the beneficial flora in the gut such as Lactobacillus, and increase autoimmune triggering bacteria, such as Prevotella.

Excessive consumption of dietary sugars has further been shown to reduce the production of short-chain fatty acids in the gut, which can lead to impaired gut barriers (aka ‘leaky gut’) and a less resilient intestinal mucosa and immune system to fight off infections.

All this can contribute to the development of unpleasant gut symptoms such as bloating, food intolerances to normally healthy foods, SIBO (small intestinal bacterial overgrowth), candida overgrowth and more (R).

5. Cellular ageing via advanced glycation end products (AGEs) and free radicals

AGEs are sugar modifications of proteins and fats, leading to a long-term disruption of cellular function even after blood glucose has normalized. They have been linked to damage of collagen, free radical formation, arterial stiffness and increased cardiovascular risk (R, R).

Blood sugar spikes also have been shown to upregulate free radical production and thereby oxidative stress genes, while at the same time downregulating antioxidant genes, making this a double whammy for free radical damage and cellular ageing.

6. Impaired healing and repair

In acute conditions such as surgery and critical illness, insulin resistance and elevated circulating glucose levels have been shown to have a negative impact on patient outcomes via impaired healing and repair (R, R).

7. Damage to our blood vessels, with an increased risk of hypertension, atherosclerosis and overall cardiovascular disease

There is a close relationship between blood vessel health, its stiffness and blood pressure. Research shows that repeated blood sugar spikes damage the lining of our blood vessels (‘endothelial dysfunction’), making it less pliable, thereby increasing blood pressure.

Studies on exact carbohydrate quantity are inconclusive, but low carbohydrate diets may be associated with lower blood pressure.

Plant-based carbohydrate-containing foods such as from whole fruits and vegetables may lower hypertension risk and 24-h blood pressure. Excessive sugar intakes from sugar-sweetened beverages are associated with higher blood pressure levels and hypertension risk, with evidence of a dose-response relationship.

Sugar intake is also associated with enhanced salt sensitivity to its effects on high blood pressure (R, R, R, R, R, R).

8. Increased levels of ‘bad’ cholesterol (LDL) and lower levels of the ‘good’ type (HDL)

Variations in the size and density distributions of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles have been related to risk for cardiovascular disease. In particular, increased levels of small, dense LDL particles, together with reduced levels of large HDL and increases in small HDL, have been shown to be integral features of the atherogenic dyslipidemia found in patients with insulin resistance, obesity, and metabolic syndrome.

Increased dietary carbohydrates, particularly simple sugars and starches with high glycemic index, have been shown to increase levels of small, dense LDL (bad!), primarily by mechanisms that involve increasing plasma triglyceride concentrations. Low-carbohydrate diets may have the opposite effects (R).

A high carbohydrate consumption at the expense of polyunsaturated fatty acids (such as the heart healthy omega 3s) has further been indicated to increase total and LDL cholesterol, but to reduce the protective HDL cholesterol. Regardless of the type of fat being replaced, a high carbohydrate intake promotes an increase in the triglyceride concentration (R, R).

9. Insulin resistance and metabolic syndrome

In addition to the cells eventually becoming less responsive to insulin’s signalling if we are continually exposed to high levels of blood sugar that necessitate insulin to shuttle it into our cells, even acute bouts of high blood sugar have been shown to impair insulin signalling through the generation of free radicals.

However, other factors like chronic low grade inflammation, lack of sleep, cortisol (our stress hormone), etc, seem to play a role in the development in insulin resistance also, which we will get into some other time (R).

AGE accumulation in key metabolically relevant organs has been shown to induce insulin resistance, inflammation, and oxidative stress, which in turn provide substrates for excess AGE formation, thus creating a feed-forward-fuelled pathological loop mediating metabolic dysfunction.

Furthermore, a high consumption of sugar-sweetened beverages increases the risk of obesity and type 2 diabetes mellitus (R).

Why the amplitude of your post-meal spikes may matter more than your average blood sugar

A recent study published at the Journal Frontiers of Cardiovascular Medicine shows that the amplitude of a spike may be a more robust determinant of CVD risk than average glucose levels (as measured by HbA1c).

The study showed that even for individuals with ‘normal’ blood sugar on average, those in the lowest (69–107 mg/dl) vs the highest (150–194 mg/dl) range of their post meal blood sugar spike, there was a 27% increased risk of CVD in those that had poorer blood sugar control and increased spikes.

Along with the amplitude, the duration outside the ’normal’ range is also likely to be important, ie how long it takes the body to get the blood sugar back into ideal ranges (R).

Another study also showed that repeated administration of hyperglycemic (high blood sugar) spikes robustly increases atherosclerosis, even if their lipid profile and HbA1c (a biomarker usually utilised to define blood sugar averages over the past months) remain unaltered (R)!

Average blood sugar (HbA1c) can also seemingly be ok, if high blood sugar spikes come hand-in-hand with blood sugar drops, bringing the average back to ‘normal’.

Low blood sugar in itself has been shown to come with a few pitfalls too.

Effects of repetitive blood sugar drops (hypoglycemia)

  • Increased risk of cardiovascular events and all-cause mortality via vascular inflammation, likely through a surge of sympathetic nervous system activity (stress response!) following the low blood sugar (R)
  • Lowered cognition, mood and consciousness

Top 10 strategies and tools to improve your blood sugar

1. Go lower carb- but avoid cutting them out entirely for extended periods of time

Number 1 tool is the obvious one. Avoiding foods that are high in sugars, including excess amounts even of healthy carbohydrates and fruits (as they do also turn into sugar inside the body, just at a slower = better rate), will lower exposure and therefor spikes. However, as with most things in life, going to the extremes is not always better. While cutting carbohydrates to very small amounts, as done in a ketogenic diet, can have great health benefits if done intermittently, staying on that path long-term and continuously may not be the best choice. Research in the past years has found detrimental effects, starting at becoming more insulin resistant, revving up our stress response and with it internally produced glucose (both the opposite of what we are trying to achieve in the first place), to even possibly damage to our heart muscle including fibrotic changes. For more detail on the pro’s and con’s of keto, and how to go about it for best health outcomes, head over to my recent blog post here, or if you prefer listening, to my podcast on the same topic.

Bottom line for this article is, go lower carb, but don’t go no carb. Stick to a well balanced, Mediterranean style diet, based on real, minimally processed foods, plenty of vegetables, some good quality protein, and 1 piece of fruit as dessert. For more information on how to put your meals together, join my next 4 week health reset (live on zoom in group coaching setting), or access the recorded version in online course format here to get started right away.

2. Opt for low glycemic index foods

A recent study revealed that healthy non-obese young men consuming a high glycaemic index diet for 7 days showed an increase in liver fat content, whereas 7 days on a low glycaemic index diet was accompanied by a small decrease in liver fat (R).

3. Swap some of your carbs with high quality protein

Studies suggest that modest substitution of carbohydrate-rich foods with protein-rich foods, both plant-based and also from lean red meats may lower blood pressure in hypertensive individuals (R).

4. Base your meals on a variety of whole foods and vegetables (rather than juicing which takes the fiber out)

A high dietary fibre intake has been shown to reduce the risk of obesity, type 2 diabetes mellitus, dyslipoproteinaemia, cardiovascular disease and colorectal cancer (R).

In addition, the Mediterranean diet has been shown to reduce the incidence of diseases such as RA compared to a high-sugar Western diet

Furthermore, there does not appear to be a significant detrimental effect of fructose when part of a healthy, balanced weight-maintaining diet (R).

Fiber, such as found in legumes, whole vegetables and fruit, has been shown to delay digestion and absorption, thereby lowering the glycemic index of the respective food (R).

Another study proved the same point. Specifically, a diet high in minimally processed, high-fiber, plant-based foods such as vegetables and fruits, whole grains, legumes, and nuts markedly blunted the post-meal increase in glucose, triglycerides, and inflammation. Additionally, lean protein, vinegar, fish oil, tea, cinnamon, calorie restriction, weight loss, exercise, and low-dose to moderate-dose alcohol each positively impact post-prandial dysmetabolism. Experimental and epidemiological studies indicate that eating patterns, such as the traditional Mediterranean or Okinawan diets (R).

Prebiotics, found naturally in a range of whole foods, selectively stimulate the growth of beneficial bacteria in the human colon and might offer protection against AGE-related pathology in people at risk of developing type 2 diabetes (R).

5. Fix your gut (and microbiome)

Generally, upon food consumption, several factors, including glucagon-like peptide (GLP-1, which has recently risen to fame due to the GLP-1 mimicking drug Ozempic), are released and stimulate insulin secretion, thereby regulating our blood sugar.

Ozempic’s rise to fame lies in its effect of lowering fasting and postprandial blood glucose by stimulating insulin secretion upon exposure to glucose.

However, one does not need to revert to drugs like Ozempic that can have serious side-effects (unless urgently ill). Our very own gut microbiome induces blood sugar regulation via short-chain fatty acids and bile acids, bacterial metabolites and GLP-1 production.

The composition of our gut microbiome (bacterial balance) can promote inflammation and insulin resistance, but can on the opposite end of the scale also act as insulin sensitizers (R).

Other studies have suggested that blood sugar control can be ameliorated by administering pre- and probiotics that may induce modifications in the microbiome. Following this idea, treatment with Lactobacillus acidophilus reduces pro-inflammatory molecules, and prebiotic inulin modulates gut dysbiosis, increasing certain good bacteria, that positively correlate with higher levels anti-inflammatory markers, and negatively correlate with inflammatory markers (R).

6. Limit caffeine intake to a few cups per day

Research suggests caffeine intake increases blood glucose levels, and prolongs the period of high blood glucose levels (R).

7. Learn to manage your stress

When stressed, our body pumps out cortisol. Research indicates that if we are high in cortisol, we become temporarily insulin resistant and less able to utilize and balance blood sugar appropriately. Moreover, our liver produces glucose (blood sugar) on its own if we are running high on adrenaline and cortisol, in order to provide energy for that imaginary tiger we are running from. In addition, when stressed, our brain reverts back to survival mode rather than making rational decision on what may be best for us, making it much harder to resist that chocolate chip cookie in front of us.

8. Get adequate amounts of sleep

Getting good sleep helps your cells be more insulin sensitive the next day, and much like stress management, will help you engage your prefrontal cortex for better food decision making.

9. Exercise

Regular exercise helps our body become more insulin sensitive.

10.Herbs, nutrients and lifestyle factors that can help with blood sugar control and reduce damage occurred

  • Studies have shown that curcumin inhibits inflammation caused by high fructose.
  • The addition of the supplement NAC diminishes the inhibitory effects of high glucose on the wound healing process (R).
  • Vitamin C has been shown to counterbalance the glucose-induced impact on endothelial function and oxidative stress (R).
  • The antioxidant alpha-lipoic acid also improves endothelial dysfunction induced by acute hyperglycemia (R).
  • Berberine (much like the drug metformin, but without the potential side-effects) has been shown to relieve intestinal inflammation and repair intestinal barrier structures. It can modify the gut microbiome, increasing the number of the ‘good’ bacteria Lactobacillus and Akkermansia, while decreasing opportunistic pathogens.
  • Sodium-butyrate supplementation also ameliorates diabetic inflammation (R).

If health optimisation, extending your health span, and inner anti-ageing is your goal, I hope this post made it clear that you want to lower your overall sugar and carbohydrate intake, without going zero carbs.

As mentioned above, stick to a well balanced, Mediterranean style diet, based on real, minimally processed foods, plenty of vegetables including their fibre, some good quality protein, and small amounts fruit and low glycemic index starches.

A great tool to track your sugar in real time is to purchase a continuous glucose monitor, such as from Freestyle Libre. They last 2 weeks, and you get a nice overview of how different foods, drinks, stress, etc affect your sugar balance.

For more information on how to put your meals together, join my next 4 week health reset (live on zoom in group coaching setting), or access the recorded version in online course format here to get started right away.

I’d love to hear your thoughts, comment below!

In Health, Mirthe

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Mirthe Precision Health

Functional Medicine Practitioner. Hormones, epigenetics, health optimisation. IG/ TikTok/ Youtube/ Fb: @mirthe_precisionhealth, www.functionalmedicine.me.uk,