The scalp, face, retroauricular region, and upper trunk are the most common sites affected by seborrheic dermatitis, an inflammatory dermatosis that tends to relapse over time. In a clinical setting, it manifests as red, inflamed areas that are coated in oily scales and frequently accompanied by itching. Cradle cap is more common among infants and adults in their 30s and 40s, however the illness affects 3-5% of the population overall. The actual cause of seborrheic dermatitis is still not well understood, even though it happens frequently [1, 2]

It is thought that seborrheic dermatitis develops as a result of a complicated interaction between the host immune system, colonization by Malassezia species, changes in sebum composition, and activity of the sebaceous glands. An important function of sebaceous glands is the production of sebum, a lipid-rich secretion that helps keep the skin's barrier function and microbiome in balance. Triglycerides, free fatty acids, squalene, wax esters, cholesterol, and cholesterol esters make up the bulk of it. Changes in the amount and quality of these lipid components may impact Malassezia growth and set off inflammatory cascades [3-5].

 
Malassezia lipases hydrolyze triglycerides, and free fatty acids from their breakdown products can irritate and inflame the skin, according to recent research. Another factor that might exacerbate inflammatory reactions is oxidative stress, which can be exacerbated by lipid peroxidation products such malondialdehyde (MDA). One component of the pathogenesis of inflammatory dermatoses is the oxidative breakdown of squalene and other lipid fractions [6, 7].

 
Although seborrheic dermatitis is known to be related with increased sebum production, there have been few prospective studies that have looked at the specific biochemical makeup of sebum and how it relates to the severity of the condition. Insight into illness causes and the identification of possible treatment targets could be greatly enhanced by a better understanding of these metabolic changes [8, 9].

 
Thus, the current prospective study set out to investigate seborrheic dermatitis patients' sebum biochemical composition and its correlation with clinical severity.

This prospective case–control study was conducted in the Department of Dermatology, G.S.L. Medical College, Rajahmundry, Andhra Pradesh, India over a period of April 2021 to March 2022. Ethical approval was obtained from the Institutional Ethics Committee prior to commencement of the study. The study included 50 clinically diagnosed patients with seborrheic dermatitis attending the Dermatology outpatient department and 50 age- and sex-matched healthy controls without any dermatological or systemic illness.

Clinical Evaluation:

Accompanying symptoms (itching, scaling), length of illness, frequency of recurrence, and medical history were all meticulously documented. The severity of the condition was determined by evaluating the redness, scaling, and overall involvement with the Seborrheic Dermatitis Area Severity Index (SDASI).

Sebum Collection:

The patients' scalps, foreheads, and nasolabial folds were used to collect sebum samples, while the controls' comparable anatomical areas were used to collect samples under standardized settings (room temperature 22-24°C, humidity 40-60%). At least 8 hours before sampling, participants were told not to wash their faces or apply any topical treatments. The samples were cautiously taken out and preserved at -20°C until biochemical analysis following a 60-minute application of Sebutape®.

Inclusion Criteria:

• Patients aged 18–60 years.
• Clinically diagnosed cases of seborrheic dermatitis.
• Patients willing to provide written informed consent.
• Newly diagnosed or untreated patients for at least 4 weeks prior to enrollment.

Exclusion Criteria:

• Patients with other inflammatory skin disorders (e.g., psoriasis, acne vulgaris).
• Patients receiving systemic or topical antifungal, corticosteroid.
• Individuals with systemic diseases such as diabetes mellitus, hepatic, renal.
• Pregnant or lactating women.
• History of smoking or chronic alcohol consumption.

Statistical Analysis:

We used the Statistical Package for the Social Sciences to enter and analyze the data. Mean ± standard deviation (SD) was used to express continuous variables. The statistical analysis was carried out using Student's unpaired t-test to compare the groups of patients and controls. The link between the SDASI score and sebum biochemical markers was evaluated using Pearson's correlation coefficient. It was deemed statistically significant if the p-value was less than 0.05.

The research comprised 50 participants, including 25 individuals with seborrheic dermatitis and 25 healthy controls who were matched for age and sex. Both groups had their sebum biochemical compositions examined and compared. We additionally looked for a correlation between the biochemical markers and the severity of the disease (SDASI score).

Table 1: Demographic and Clinical Characteristics of Study Participants

Table 1 shows the participants' demographic and baseline medical information. Neither the gender nor the age distribution of the patients nor the controls differed significantly from one another (p > 0.05). With an average SDASI score of 8.6 ± 3.2 and a mean duration of 4.2 ± 2.1 years, seborrheic dermatitis was characterized as a medium to moderately severe condition.

Table 2: Comparison of Total Sebum Secretion and Total Lipid Content

*Statistically significant

Patients with seborrheic dermatitis had significantly higher levels of sebum secretion and total lipid content (p < 0.001) as compared to controls, as seen in Table 2. This indicates that affected individuals may have increased activity of the sebaceous glands.

Table 3: Comparison of Sebum Lipid Fractions

*Statistically significant

Patients' levels of triglycerides and free fatty acids are significantly higher than controls' levels (p < 0.001), as seen in Table 3. The levels of cholesterol were likewise markedly elevated, though to a lesser extent. Inflammation and irritation of the skin could be brought on by an increase in free fatty acids.

Table 4: Comparison of Squalene and Lipid Peroxidation Marker (MDA)

*Statistically significant

According to Table 4, patients with seborrheic dermatitis had significantly lower squalene levels and significantly higher MDA levels (p < 0.001). When MDA levels are high, it means that oxidative stress and lipid peroxidation are both elevated in the affected population.

Table 5: Correlation between Sebum Biochemical Parameters and SDASI Score

*Statistically significant

Sebum secretion, free fatty acid levels, malondialdehyde (MDA) levels, and illness severity (SDASI score) are positively correlated, as shown in Table 5. On the other hand, there was a strong inverse relationship between squalene levels and SDASI score. This research provides more evidence that seborrheic dermatitis is clinically worsened by increased lipid peroxidation and changed sebum composition.

This study assessed the biochemical makeup of sebum in individuals with seborrheic dermatitis and compared the results with those of healthy controls. The findings revealed a notable elevation in total sebum output, triglycerides, free fatty acids (FFA), cholesterol, and malondialdehyde (MDA), accompanied by a substantial decrease in squalene levels [10]. Moreover, numerous biochemical markers exhibited a substantial link with disease severity, as evaluated by the SDASI score, indicating a strong association between modified sebum biochemistry and the clinical course of seborrheic dermatitis [11, 12].

This study revealed that patients demonstrated markedly elevated sebum excretion relative to controls, signifying increased sebaceous gland activity. Elevated sebum production establishes a lipid-rich milieu that promotes the proliferation of Malassezia species, recognized as significant contributors to the etiology of seborrheic dermatitis. Excessive sebum can compromise skin barrier integrity and induce inflammatory reactions [13-15].

This study found significantly higher levels of triglycerides and free fatty acids in patients. Triglycerides are a primary component of sebum and act as substrates for lipase enzymes generated by Malassezia. The hydrolysis of triglycerides leads to the liberation of free fatty acids, some of which exhibit irritating and pro-inflammatory characteristics. The elevated FFA levels noted in our patients may consequently lead to erythema, scaling, and pruritus. The significant connection between FFA levels and SDASI scores further substantiates their contribution to disease severity [16, 17].

This study found that squalene levels were markedly decreased in patients with seborrheic dermatitis. Squalene is a vital sebaceous lipid possessing antioxidant capabilities that safeguards skin surface lipids from oxidative harm. The depletion may make sebum more prone to oxidation, resulting in the generation of reactive lipid peroxidation products. The decrease in protective lipid components may exacerbate persistent inflammation [18, 19].

This study revealed considerably raised MDA levels in patients, indicating heightened lipid peroxidation and oxidative stress. MDA is a prominent indicator of the oxidative breakdown of polyunsaturated fatty acids. The favorable link between MDA levels and SDASI score indicates that oxidative stress escalates with heightened disease severity. Oxidative damage to sebum lipids may produce inflammatory mediators that exacerbate cutaneous irritation [20].

Previous research has indicated elevated sebum production and modified lipid composition in individuals with seborrheic dermatitis, corroborating our findings. Previous studies have emphasized the contribution of Malassezia-derived lipases in elevating free fatty acid levels on the skin surface. These investigations substantiate the concept that qualitative alterations in sebum lipids, rather than solely an increase in sebum volume, are pivotal in disease development [21, 22].

Previous research demonstrated that oxidative stress and lipid peroxidation lead to inflammatory skin conditions, such as seborrheic dermatitis. Decreased levels of antioxidant components like squalene are linked to heightened vulnerability to lipid oxidation. The interaction of oxidative stress, microbial colonization, and immune response has been suggested as a crucial pathogenic process, consistent with the findings of the current investigation [22].

The data indicate that seborrheic dermatitis is linked to substantial quantitative and qualitative changes in sebum lipids, as well as heightened oxidative stress. These metabolic alterations seem to correlate with clinical severity, suggesting their probable involvement in illness progression. Focusing on sebum composition and oxidative stress pathways may thus constitute a promising therapeutic strategy for managing seborrheic dermatitis. Nonetheless, more extensive longitudinal investigations are necessary to clarify causal linkages and assess the effects of therapeutic therapies on sebum biochemistry [23, 24].

The current prospective study shows significant quantitative and qualitative changes in sebum composition in seborrheic dermatitis patients. In affected individuals, increased sebum secretion, triglycerides, free fatty acids, lipid peroxidation marker (MDA), and squalene levels indicate increased sebaceous activity and oxidative stress. The positive connection of free fatty acids and MDA with disease severity and the negative correlation of squalene with SDASI score show that sebum biochemical alterations are closely linked to clinical progression of seborrheic dermatitis. These data suggest that altered lipid metabolism and oxidative imbalance contribute significantly to disease development. Sebum biochemical markers may reveal disease activity and severity. Larger trials with longitudinal follow-up are needed to determine the therapeutic effects of addressing sebaceous lipid composition and oxidative stress in seborrheic dermatitis.

Funding

None

Conflict of Interest:

None

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