The present study investigated primary care patients (Swedes and Middle Easterners). It analysed differences within and between the groups regarding (i) sexual health factors and (ii) differences in vitamin D levels.
One-third of all patients reported sexual dysfunction. Compared to Swedes, Middle Easterners had significantly lower sexual dysfunction prevalence and odds of having sexual dysfunction. After adjustment for all covariates (including vitamin D), differences between the groups changed to nonsignificant. This suggests that vitamin D status might help explain the observed difference in probability regarding sexual dysfunction. No significant differences existed between Swedes and Middle Easterners regarding self-reported sexual desire or sex life satisfaction.
Results of the present study were unexpected regarding reporting worsen sexual life in Swedish-born than in Middle Eastern-born patients and not aligned with the results of other studies. Malavige et al reported no significant difference in erectile dysfunction (ED) prevalence between south Asians and Europeans. And premature ejaculation was significantly more common in south Asian males. That said, the present study and this study may not be comparable due to differences in population and methods (13). Another study of males from the Middle East and south Asia reported that most patients who sought care at a clinic in London were of north African, Middle Eastern, or south Asian descent (14). Both studies involved males only, which is not similar to the present study that included males and females.
But a Swedish study with a sample comparable to the present study reported findings that were not aligned with findings in the present study either. That particular Swedish study found a higher prevalence of decreased sexual desire in Assyrians than in Swedes – and no differences in sexual function. Although the study was methodologically similar to the present study, it only included patients with type-2 diabetes (15).
Other studies reported higher prevalence of vitamin D deficiency in Middle Easterners living in Europe than in native Europeans (18, 21), and the present study confirmed this finding. This isn’t surprising because evidence in this area is strong. Skin colour is one (but not the only potential cause of this difference).
Moreno-Reyes et al reported that Moroccans and Turks residing in Brussels had higher vitamin D levels than residents from the Congo – even though the Congolese had darker skin colour (21). These researchers suggested that it might be due to factors such as socio-economic status and UVB light exposure rather than differences in diet, because few food items contain significant amounts of vitamin D. The present study only included Middle Easterners. So no vitamin D deficiency comparison could occur between Middle Easterners and other immigrant groups.
Another study with 1231 participants reported higher vitamin D deficiency prevalence in Turkish immigrants than in ethnic Germans – and even higher prevalence in Turkish females who totally covered their bodies (18). This finding suggests that limiting the amount of sunlight that reaches the skin (with clothing) can affect vitamin D levels (18). And while the present study did not investigate clothing, the populations are comparable, and the present study yielded similar result.
The present study also found significant gender differences regarding insufficient sexual desire and sexual function among Swedes. Age explained differences between genders (Swedish) in those who reported sexual dysfunction. Covariates could not explain gender differences regarding insufficient sexual desire among Swedes nor could they explain the probability of reporting insufficient sexual desire.
The aforementioned discrepancies call for further investigation. Explanations could be found in deeper investigation of hormonal disturbances or mental health. But among Middle Easterners, those with lower vitamin D levels had significantly lower risk for reporting insufficient sexual desire than those with normal vitamin D levels. This was unexpected but might be explained by perceptions about sex life and mental health rather the physiological pathology. Further, deeper investigations of the sexual desire among Middle Easterners are also warranted.
A growing number of studies reported age-related increases in sexual dysfunction in males – largely attributable to performance disturbances due to atherosclerosis (8, 9, 22). Consequently in the present study, age was expected to be a significant covariate.
Multimorbidity and polypharmacy in older persons might explain this – as might psychological issues. In addition, the present study’s population had risks for developing type-2 diabetes – a disease associated with fatigue, depression, and other health conditions that affect sex life.
Strengths and limitations
The material used in the present study consists of data that was the first of its kind to be gathered in Sweden. The aforementioned 4-D diabetes and vitamin D studies were the first to compare sexual health factors among Swedes and Middle Easterners. Covering so many factors can be a strength – if a general overview of health is the aim. But it may also be a weakness, because the questionnaire only briefly dealt with sexual health.
Results from the present study imply that greater prevalence of low vitamin D levels among Middle Easterners could be associated with higher risk for sex life dissatisfaction. A Deleskog et al study suggested that vitamin D levels can trigger sex life dissatisfaction – a common complaint among patients with type-2 diabetes. Not unlike patients in the Deleskog study, patients in the present study had higher risk for developing type-2 diabetes. And this suggests that they should be tested for vitamin D levels – as a proxy for type-2 diabetes within 10 years – and be subscribed vitamin D for type-2 diabetes prevention, which the Deleskog study recommended (23). The Deleskog study included non-immigrant population resettled in Stockholm and the results were that those with prediabetes had lower vitamin D levels and higher diabetes risk as measured after 10 years. However, because this was a cross-sectional study, it was not possible to determine causality, i.e., whether the difference in vitamin D levels caused the difference in reporting declined sexual health, in general, and sex life dissatisfaction, in particular. Instead, causes not included in the statistical analysis, such as differences in diet, health conditions, amount of exercise, or measurement of vitamin D levels during different seasons (winter or summer) may explain the findings.
The previously published studies of patients on haemodialysis concluded that treatment with vitamin D did not improve sexual function in patients with vitamin D deficiency (24, 25). But this could be because of the patients’ other medical condition. One study investigated treatment of 102 healthy middle-aged males with vitamin D deficiency and ED with high dosage of ergocalciferol, a form of vitamin D, over at least 12 months. The men’s ED improved, their testosterone increased, and their HbA1c decreased (17). The researchers also observed a small decrease in the men’s BMI (16). Clearly, knowledge of this area is insufficient and further studies on effects of treatment with different forms of vitamin D are highly needed.
Another limitation of the present study was type of questions asked. Because of the nature of the two studies from which the data for this study were collected (they were general overviews of the participants’ health), the questionnaire only briefly touched on sexual health with three issues: ability, desire, and satisfaction. For example, impaired sexual function consist of one single yes/no question without detailed categorization into its specific aetiologies (e.g., ED, dyspareunia). Fuller investigation of the topic would require additional questions.
The present study included patients from the countries of origin of large immigrant groups in Sweden. This makes results of the study readily applicable to a large part of the Swedish immigrant population. But the study sample may not be representative of immigrants who came to Sweden very recently – many of whom come from Syria and Afghanistan. Although it may be plausible to assume that results of the present study may be applicable to immigrants from Syria (because of geographic proximity of Syria to countries included in the present study), it is less likely that they are applicable to immigrants from Afghanistan, due to geographic distance and perhaps cultural and religious differences.
The skewed sex distribution in the present study’s population (58.8% female) may make the results more applicable to females than males. It also makes it harder to compare the present study’s results to those of other studies, because many previous studies investigated ED and vitamin D. That said, gender distribution of the Swedes and the immigrants did not vary significantly in present study; consequently, the skewed distribution did not affect comparison between these two groups – as seen when gender was add in the logistic regression.
Some factors may render the present study’s population as not representative of the entire population of Sweden because it is based on primary care patients. The present study lacks information regarding patients who refused to participate in the aforementioned 4-D diabetes and vitamin D studies. Only patients seeking care at a primary care centre were included, which means that people who were healthy or for some other reason did not seek primary health care were not included in the studies. So compared to the general population, the present study’s population may contain a larger proportion of people with chronic health conditions that can affect sexual health. Recruitment occurred in two areas outside Stockholm with high immigrant populations, which might make the results more difficult to apply to the population of other areas in Sweden. Recruitment at multiple geographic locations – and not limited to patients – is warranted for future studies.
Although the results of the present study may not be applied clinically because the study did not established any kind of causality, it provides ideas for future clinical studies that could investigate possible vitamin D treatment effects. The present study lacked data on whether or not participants in the 4-D diabetes study were treated with vitamin D supplements. If found effective in such studies, the vitamin D supplementation could possibly contribute to treatment for sexual health problems. It might also have positive effects on other aspects of health, because other symptoms are linked to vitamin D deficiency (26, 27).