Researchers at the National University of Singapore studied how various vitamins, micronutrients, and antioxidants affect the risk of autoimmune diseases. They found that consumption of most vitamins, micronutrients and antioxidants may not have any effect on the risk of autoimmune diseases.
“However, among the different vitamin D dosages, subgroup analysis demonstrated that those who were supplemented with 600–800IU/day may have a statistically significant reduction in risk,” wrote researchers in Frontiers in Immunology.
For those who took vitamin D supplements of 600–800IU/day, the risk ratio was 0.55 – significantly lower compared to other dosage groups, whose risk ratios ranged from 0.79–1.2.
Researchers also observed a bimodal pattern of vitamin D supplementation, where daily doses of less than 200 IU or greater than 5000 IU were linked to an increased incidence of autoimmune diseases.
For example, those who took daily doses of vitamin D at less than 200IU/day had a risk ratio of 0.89, while those who took more than 5,000IU/day had risk ratios of 1.17–1.2.
The results also showed that those who consumed both dietary and supplementary vitamin D had a higher risk ratio of 1.26 as compared to those on supplementation alone, who had a lower risk ratio of 0.85.
This indicated that excessive supplementation can also cause toxicity.
Researchers therefore emphasised the need to carefully consider dosage variability, particularly for vitamin D, when using these supplements preventively: “We highlight the importance of dosage variability when considering prophylactic usage of such supplements, especially for vitamin D.”
Managing autoimmune disease risk
Autoimmune diseases pose significant health challenges worldwide and affect millions.
The prevalence of autoimmune and inflammatory diseases continues to rise despite existing immunosuppressive medications that dampen the body’s immune responses against self.
In recent years, there has been growing interest in exploring preventive strategies through nutritional interventions using vitamins, antioxidants, and micronutrients to reduce the risk of developing autoimmune diseases.
Smoking, age, physical or outdoor activity and diet were significant confounding factors that affected the efficacy of such interventions, researchers said.
Therefore, this study could help unravel more definite relationships with supplementation and the development of incident autoimmune diseases.
Researchers reviewed a total of 18 studies that included regions in Australia and the Middle East – eight studies reported on multiple sclerosis, another eight reported on rheumatic arthritis, and two studies reported on systemic lupus erythematosus. Two studies did not report the specific autoimmune disease.
The exposures included vitamins A, B, C, D, E, multivitamins, iron, calcium, omega-3, zinc, and dietary antioxidants.
Among 945,471 participants, 4,591 patients developed autoimmune diseases.
Researchers observed that the type of autoimmune disease did not significantly affect the risk of developing autoimmune diseases after consumption of supplementary vitamin D. Other variables such as country of study, gender, and age were also not found to significantly reduce the risk of autoimmune diseases.
Effects of vitamins, micronutrients, and antioxidants
Emerging research suggests that nutritional interventions, specifically through supplementation, could have a pivotal role in altering the risk of developing autoimmune conditions.
Vitamins, in particular vitamin D, and antioxidants such as omega-3 fatty acids, have garnered attention for their potential anti-inflammatory effects. They are also said to have modulatory effects on the immune system.
However, the study found that supplementation with vitamin C, B, multivitamins, iron, and omega-3 did not significantly decrease the risk of autoimmune diseases. Additionally, vitamin E supplementation demonstrated a statistically insignificant increase in risk of autoimmune disease.
However, researchers of this study observed that supplementation with vitamin C, B, multivitamins, iron, and omega-3 showed a statistically insignificant decrease in the risk of autoimmune diseases, with risk ratios ranging from 0.40 to 0.98, and wide confidence intervals (CI) indicating uncertainty.
The risk ratios for each supplement were as follows: vitamin C (0.48, 95% CI: 0.07–3.26), vitamin B (0.40, 95% CI: 0.04–4.10), iron (0.52, 95% CI: 0.07–3.75), multivitamins (0.89, 95% CI: 0.69–1.15), and omega-3 (0.98, 95% CI: 0.84–1.14), none of which showed a significant reduction in risk.
Additionally, vitamin E supplementation demonstrated a statistically insignificant increase in the risk of autoimmune diseases, with a risk ratio of 1.17 (95% CI: 0.65–2.10).
While supplementation of certain vitamins and micronutrients did not show significant effects, the study’s broader findings, including demographic factors, provide further insight into managing autoimmune disease risk.
Going forward
While autoimmune diseases often peak before 60, age remains a significant risk factor. Smoking is also well-established as a risk factor.
Conversely, increased physical outdoor activity was associated with a reduced risk of autoimmune diseases, potentially due to the benefits of physical activity on immune regulation and inflammation, as well as the protective effects of sunlight exposure in reducing the risk of multiple sclerosis.
This study primarily focused on the correlation between vitamin D supplementation and autoimmune disease risk, but the inclusion of other vitamins, micronutrients and antioxidants adds complexity to the findings, said researchers.
However, limited data for these factors underscores the need for caution in drawing definitive conclusions.
“While vitamin D stands as the most extensively investigated vitamin in relation to its role in modulating autoimmunity and the development of autoimmune diseases, the findings highlight the potential contributions of other vitamins, micronutrients, and antioxidants in reducing the risk of autoimmune diseases.
“Our study opens avenues for future research to build upon by expanding sample sizes and employing longitudinal designs to better understand temporal relationships,” researchers concluded.
For instance, exploring interactions between micronutrients could reveal details not covered in this study. Conducting rigorous randomised controlled trials with specified dosages and accounting for confounding factors would help researchers draw stronger conclusions.
Source: Frontiers in Immunology
DOI: https://doi.org/10.3389/fimmu.2024.1453703
“Vitamin, antioxidant and micronutrient supplementation and the risk of developing incident autoimmune diseases: a systematic review and meta-analysis”
Authors: Chen Ee Low, Sean Loke et al.
