Sugar & Eczema/Psoriasis: The mTORC1 Mechanism, AGEs & What the Evidence Actually Shows
The connection between high sugar intake and inflammatory skin conditions is more specific than "sugar causes inflammation generally." There are identified mechanisms through which excess dietary sugar contributes to the inflammatory pathways driving both eczema and psoriasis — and understanding them makes the practical dietary guidance more compelling than a vague recommendation to "eat less sugar."
That said, sugar is not the primary driver of either condition. Both eczema and psoriasis have genetic and immune underpinnings that diet cannot address alone. The honest framing is that high sugar intake amplifies the inflammatory environment in which both conditions operate — reducing it helps, but it isn't a cure.
Can sugar worsen eczema or psoriasis?
Possibly — high sugar intake may contribute to inflammation, blood sugar spikes, and immune dysregulation that could worsen eczema and psoriasis symptoms in some people. But "possibly" undersells what the evidence actually shows, and the mechanisms involved are more specific and more directly relevant to both conditions than the vague "sugar causes inflammation" framing that dominates most dietary content about skin conditions. The insulin and IGF-1 spike from high-glycaemic eating activates mTORC1 — the same intracellular signalling pathway that drives keratinocyte hyperproliferation in psoriasis and amplifies the Th2 immune response relevant to eczema — through a route that is distinct from, and compounding with, the NF-κB inflammatory pathway that processed foods and alcohol activate. Fructose adds a further dimension specific to psoriasis: its hepatic metabolism pathway contributes to the non-alcoholic fatty liver disease that is two to three times more prevalent in psoriasis patients and that worsens systemic inflammatory burden through the hepatodermal axis covered in the liver psoriasis article in this series. Whether sugar is a significant personal trigger varies between individuals — but the mechanisms through which it could worsen both conditions are specific, documented, and considerably more interesting than the answer "possibly" implies.
How sugar affects inflammation: the specific mechanisms
Advanced glycation end-products (AGEs). When sugar molecules bind to proteins and fats in the body — a process called glycation — they form advanced glycation end-products. AGEs activate RAGE (receptor for advanced glycation end-products), triggering NF-κB signalling — the master inflammatory switch discussed throughout this series in the context of psoriasis, eczema, and acne. AGE formation is directly proportional to circulating glucose levels, making high-sugar diets a direct driver of NF-κB-mediated inflammatory cytokine production.
This is one of the most specific mechanistic connections between sugar and skin inflammation, and it applies to both conditions rather than being eczema or psoriasis-specific.
Insulin and IGF-1 elevation. High-glycaemic foods raise insulin rapidly, which in turn raises IGF-1 (insulin-like growth factor 1). As covered in the hormonal acne diet article, IGF-1 activates mTORC1 — a cellular signalling complex that promotes inflammatory activity and keratinocyte proliferation. In psoriasis specifically, where keratinocyte hyperproliferation drives plaque formation, consistent IGF-1 elevation through high-glycaemic eating contributes directly to one of the condition's core pathological mechanisms.
Gut microbiome disruption. High sugar and ultra-processed food intake consistently reduces gut microbiome diversity — specifically depleting beneficial bacteria including the Faecalibacterium prausnitzii species that is documented to be lower in psoriasis patients, as covered in the probiotics and leaky gut articles in this series. The gut-skin axis means microbiome disruption from high-sugar diets has downstream effects on systemic immune regulation relevant to both conditions.
Oxidative stress. Elevated blood glucose generates reactive oxygen species — free radicals that overwhelm antioxidant defences and contribute to cellular oxidative stress. Oxidative stress amplifies inflammatory responses in skin cells and is elevated in both psoriasis and eczema. This is separate from the AGE mechanism and represents an additional pro-inflammatory pathway.
Why the evidence is stronger for psoriasis than eczema
This is worth addressing directly because the original article correctly identified it but without explanation.
Psoriasis and metabolic syndrome. Psoriasis is strongly associated with metabolic syndrome — insulin resistance, dyslipidaemia, elevated blood pressure, and central obesity. This comorbidity cluster shares pathological mechanisms with high-sugar dietary patterns: both involve elevated inflammatory cytokines, elevated insulin and IGF-1, and oxidative stress. The association between obesity/metabolic syndrome and psoriasis severity is one of the most consistently documented findings in psoriasis research.
In overweight psoriasis patients, the dietary factors that contribute to metabolic dysfunction — including high sugar intake — are directly relevant to psoriasis severity. Multiple studies have found PASI score improvements with weight loss, which broadly involves reduced sugar and glycaemic load alongside reduced calories.
Eczema and sugar. The relationship is less direct. Eczema's primary drivers — filaggrin deficiency, Th2 immune dysregulation, IgE sensitisation — are not specifically amplified by sugar in the way that psoriasis's Th17/mTORC1 pathways are. The gut microbiome disruption from high-sugar diets does influence the gut-skin axis relevant to eczema, and AGE-mediated inflammation is broadly relevant, but eczema is less tied to the metabolic syndrome cluster than psoriasis. Some people with eczema report clear reactivity to high-sugar foods — but this is more likely through the gut microbiome and general inflammatory load mechanisms than through a specific eczema pathway.
The type of sugar matters
Not all sugar has the same impact. This distinction is worth making explicitly:
Added sugar in processed foods — sucrose, high-fructose corn syrup, glucose syrup — produces rapid blood glucose spikes, drives insulin and IGF-1 elevation, and contributes to the metabolic dysfunction associated with psoriasis severity. Ultra-processed snacks, sugary drinks, pastries, confectionery, and breakfast cereals with added sugar are the primary contributors.
Fructose — particularly concentrated fructose from sugary drinks and processed foods — is metabolised primarily in the liver and has specific associations with non-alcoholic fatty liver disease (NAFLD), which as noted in the milk thistle article is significantly more prevalent in psoriasis patients. High fructose intake directly contributes to this hepatic inflammatory burden.
Natural sugars in whole fruit come packaged with fibre, polyphenols, vitamins, and water that substantially change the metabolic impact. Whole fruit has a much lower glycaemic response than equivalent sugar from processed foods, and the polyphenols actively counter some of the inflammatory effects. The fruits with the most evidence for anti-inflammatory benefit in eczema and psoriasis are covered in the fruits article in this series. Restricting whole fruit intake in the belief that "sugar is bad" is both nutritionally unnecessary and counterproductive.
Does cutting out sugar cure eczema or psoriasis?
No.
Reducing sugar may help some people:
feel less inflamed
improve overall health
reduce flare frequency
But neither eczema nor psoriasis is caused solely by sugar.
These conditions are still driven by:
immune dysfunction
genetics
skin barrier issues
environmental triggers
What actually helps: practical dietary changes
The goal isn't elimination of all sugar — which is neither achievable nor necessary. It's reducing the main contributors to sustained high insulin and IGF-1, AGE formation, gut microbiome disruption, and metabolic dysfunction:
Reduce significantly: sugary drinks (the highest-impact single change), ultra-processed snacks and confectionery, pastries and refined bakery products, breakfast cereals with added sugar, and white bread and refined carbohydrates at high frequency.
Replace with: whole grain alternatives, legumes (low glycaemic, high fibre, prebiotic), vegetables as the primary carbohydrate source, oily fish and nuts for healthy fats, and whole fruit for sweetness and polyphenols.
Monitor alcohol separately. As covered in the diet articles across this series, alcohol is one of the most consistently documented psoriasis triggers — and many alcoholic drinks (beer, sweet wine, cocktails) carry significant sugar loads on top of alcohol's direct inflammatory effects.
Should you avoid sugar completely?
Usually not.
For most people:
moderate sugar intake is unlikely to be the sole issue
extreme restriction can become stressful and unsustainable
A balanced, anti-inflammatory diet is generally more realistic and effective than cutting out all sugar.
What sugar reduction realistically achieves
For most people with eczema or psoriasis, meaningfully reducing added sugar and high-glycaemic food intake:
Reduces baseline inflammatory marker levels over 4–8 weeks of consistent change. Supports gut microbiome diversity. In overweight individuals with psoriasis, contributes to the weight reduction that most consistently correlates with PASI improvement. Reduces the mTORC1 and IGF-1 drive on keratinocyte activity relevant to psoriasis. Does not replace medical treatment or address the genetic and immune foundations of either condition.
The most realistic expectation is a modest reduction in flare frequency and severity as part of a consistent anti-inflammatory dietary pattern — not dramatic clearance.
Foods that may be more problematic
Highly processed sugary foods
sweets and candy
fizzy drinks
pastries
ultra-processed snacks
These may contribute more to inflammation than natural sugars.
Sugary drinks
Linked to:
blood sugar spikes
inflammation
metabolic dysfunction
Better alternatives for skin health
Fruit
Provides:
antioxidants
fibre
vitamins
Whole fruit is generally healthier than refined sugar.
Anti-inflammatory foods
Including:
oily fish
vegetables
nuts and seeds
olive oil
These dietary patterns are more strongly linked to skin health improvements
Signs sugar may be affecting your skin
You may notice flare-ups after:
sugary snacks
processed foods
binge eating sugar
Keeping a food diary may help identify personal triggers.
Skin support for eczema & psoriasis-prone skin
The antioxidant defences relevant to counteracting AGE-mediated inflammation — vitamin C, CoQ10, and vitamin E — are addressed through both dietary improvement and targeted supplementation.
Drought's Skin Support Formulaprovides vitamin C, CoQ10, zinc, vitamin D, and 10 other nutrients selected for their roles in skin barrier function and immune regulation — addressing the nutritional dimensions that dietary improvement alone doesn't fully cover. Made in the UK, suitable for vegetarians, designed for consistent long-term daily use.
FAQs: Sugar, eczema & psoriasis
Does sugar worsen eczema and psoriasis?
Yes — through specific mechanisms rather than vague "sugar causes inflammation." High-glycaemic sugar raises insulin and IGF-1, activating mTORC1 — the intracellular kinase pathway that drives keratinocyte hyperproliferation in psoriasis and amplifies Th2 immune activity in eczema. Simultaneously, sugar reacts with skin proteins through non-enzymatic glycation, producing Advanced Glycation End-products (AGEs) that activate RAGE receptors on keratinocytes and immune cells, triggering NF-κB and inflammatory cytokine production. AGEs accumulate in skin collagen and are significantly elevated in psoriasis patients compared to healthy controls. The effect is more consistently documented in psoriasis than eczema — but both conditions have specific mechanistic pathways connecting high-glycaemic eating to disease severity.
Which types of sugar are worst for eczema and psoriasis?
Refined sugar and high-fructose corn syrup in ultra-processed foods carry the highest combined mechanism load. High-glycaemic refined sugar produces the fastest insulin-IGF-1-mTORC1 activation — explaining why sugary drinks, pastries, and processed snacks worsen psoriasis and eczema more consistently than equivalent calories from whole fruit. Fructose — particularly the high concentrations in high-fructose corn syrup — is processed primarily by the liver rather than requiring insulin, producing hepatic inflammation and VLDL production that contributes to the metabolic syndrome comorbidity in psoriasis. Whole fruit's natural sugar is packaged with fibre, polyphenols, and water that moderate the glycaemic response and simultaneously provide anti-inflammatory compounds — a fundamentally different metabolic picture from the same fructose in a soft drink.
Can cutting out sugar improve eczema?
For some people — yes, meaningfully. The gut microbiome mechanism is the most specific eczema-sugar connection: ultra-processed high-sugar diets reduce Faecalibacterium prausnitzii and Bifidobacterium species, increasing intestinal permeability and LPS translocation that amplifies Th2 immune activity. Consistent reduction in high-glycaemic ultra-processed food — rather than blanket elimination of all sugar — typically produces more sustainable gut microbiome improvement. Four to eight weeks of consistent dietary change is the minimum assessment period. People whose eczema is most consistently food-reactive rather than contact or environmental-reactive are most likely to notice dietary sugar benefit.
Does sugar directly cause psoriasis flare-ups?
Through mTORC1 activation — yes, more directly than for eczema. mTORC1 stimulates the keratinocyte proliferation that is psoriasis's defining skin feature, and its activation by insulin and IGF-1 from high-glycaemic eating provides a direct kinase pathway from diet to disease activity. The metabolic syndrome association with psoriasis — significantly higher rates of insulin resistance, obesity, and dyslipidaemia in psoriasis patients — reflects shared upstream mechanisms rather than coincidence. Weight loss in overweight psoriasis patients consistently reduces PASI scores through reduced adipokine inflammatory signalling and improved insulin sensitivity — both addressing mTORC1 through the same upstream pathway as dietary glycaemic reduction.
Is fruit bad for eczema and psoriasis?
No — and the reasoning is mechanistically specific. Whole fruit's natural fructose is accompanied by soluble fibre that moderates absorption speed, polyphenols with documented NF-κB inhibitory activity, and vitamins relevant to barrier and immune function. The mTORC1 and AGE mechanisms that make refined sugar problematic for eczema and psoriasis are substantially moderated by the fibre-polyphenol-vitamin package in whole fruit. The glycaemic index of whole fruit is considerably lower than refined sugar products for the same reason. Two to three servings of whole fruit daily is appropriate — the concern about sugar worsening eczema and psoriasis applies to refined and ultra-processed sugar rather than to whole fresh fruit.
Does honey or maple syrup affect eczema and psoriasis differently from refined sugar?
Marginally — but not significantly enough to change the practical guidance. Honey contains fructose and glucose alongside small amounts of antioxidants and antimicrobial compounds; its glycaemic index is slightly lower than refined white sugar but not dramatically so. Maple syrup contains manganese, zinc, and some antioxidants alongside its sugar content. Neither provides the fibre, polyphenol, or vitamin content that makes whole fruit metabolically distinct from refined sugar. Both activate the insulin-IGF-1-mTORC1 pathway at doses comparable to refined sugar — they are more complex than white sugar but not categorically different for eczema and psoriasis management purposes. A small amount of either in cooking is unlikely to be meaningful; using either as a primary sweetener at high quantities carries similar mechanism concerns to refined sugar.
Should I keep a food diary to identify sugar as a personal trigger?
Yes — and with specific tracking parameters. Record sugar consumption alongside skin state with a 24–48 hour lag rather than same-day correlation — the delayed Th2 and mTORC1 downstream skin effects mean a sugary meal on Monday is more likely to correlate with a flare on Tuesday or Wednesday than on Monday itself. Track sugar quantity and type separately — distinguishing whole fruit from processed sugar, and drinks from solid food, allows more specific identification of which sugar sources correlate with your individual pattern. Four weeks of consistent diary keeping before drawing conclusions — eczema and psoriasis fluctuate naturally with stress, sleep, hormonal cycles, and seasonal factors that create false correlations without a sufficient observation period.
Summary
High sugar intake worsens eczema and psoriasis through specific mechanisms — AGE-mediated NF-κB activation, insulin/IGF-1-driven mTORC1 signalling, gut microbiome disruption, and oxidative stress. The evidence is stronger for psoriasis through its documented association with metabolic syndrome and insulin resistance. Added sugar from processed foods and sugary drinks is the primary target; whole fruit sugar is not a meaningful concern and whole fruit has anti-inflammatory value for this audience. Meaningful reduction in added sugar as part of a consistent anti-inflammatory dietary pattern modestly reduces flare frequency and systemic inflammatory burden — working alongside medical treatment and nutritional support rather than replacing either.
Written by the Drought Skin team — specialists in natural support for psoriasis, eczema and acne
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