From Virus, to Sunshine, to Gender - What Causes MS??

Multiple sclerosis (MS) affects over 2.8 million people globally, disrupting the brain and spinal cord’s ability to communicate with the body, leading to symptoms like fatigue, difficulty walking, and cognitive challenges. Despite being a widespread issue, the precise causes of this autoimmune disease remain a mystery.

That said, the research is constantly evolving, and scientists have uncovered a web of genetic, environmental, and lifestyle factors that contribute to its development. By understanding these causes, you can take proactive steps to manage your risk or live better with MS. In this guide, we dive into the latest research to explain what drives MS, offering practical insights and hope through actionable lifestyle changes.

Genetic Roots: How Your DNA Shapes MS Risk

Your genes play a significant role in whether you might develop MS. A landmark study by the International Multiple Sclerosis Genetics Consortium and Wellcome Trust Case Control Consortium 2 (2011) identified 57 genetic variations linked to MS, many tied to how your immune system functions. One key genetic marker, called HLA-DRB1*1501, significantly increases MS risk, especially in people of European descent. This marker influences how your immune system responds to threats, sometimes mistakenly attacking your own body, as happens in MS.

Beyond this, certain genes affect how your body processes vitamin D, a nutrient critical for immune health. For example, variations in the CYP27B1 gene, which helps activate vitamin D, can raise MS risk by limiting its protective effects. While these genetic factors set the stage, they don’t act alone—your environment and lifestyle can either amplify or reduce their impact.

What This Means for You: If MS runs in your family, you may have a higher genetic risk, but it’s not a done deal. Factors like diet, sunlight exposure, and healthy habits can influence how your genes behave, giving you some control over your risk.

Environmental Factors: The World as a Trigger

Where you live and what you’re exposed to can shape your MS risk in surprising ways. Let’s explore two major environmental players: vitamin D and viral infections.

Vitamin D and Sunlight: A Protective Shield

Low vitamin D levels are a well-established risk factor for MS, as detailed in a comprehensive review by Pierrot-Deseilligny and Souberbielle (2017). Vitamin D, often called the “sunshine vitamin,” is produced when your skin absorbs ultraviolet B (UVB) rays from sunlight. In regions far from the equator (think Canada, Scandinavia, or the northern U.S.) sunlight is weaker, especially in winter, leading to widespread vitamin D deficiency. This is why MS is more common in these areas compared to sunny, tropical regions.

Studies show that people with higher vitamin D levels (above 30 ng/mL) during childhood, adolescence, or pregnancy have up to a 60% lower chance of developing MS. Vitamin D helps regulate your immune system, calming overactive responses that drive MS. For those already living with MS, correcting vitamin D deficiency with supplements (2000–4000 IU daily) can reduce relapse rates by 50–70% in the relapsing-remitting form of the disease. This is because vitamin D boosts anti-inflammatory immune cells, like regulatory T cells, while taming harmful ones.

What This Means for You: If you live in a low-sunlight area or spend a lot of time indoors, you might be at higher risk for vitamin D deficiency. Getting your vitamin D levels tested, spending safe time in the sun, or taking supplements under medical guidance can help protect your immune system and lower MS risk or relapses.

Viral Infections: The Epstein-Barr Connection

Viral infections, particularly the Epstein-Barr virus (EBV), are another critical environmental factor. EBV, which causes mononucleosis (often called “mono”), is found in nearly all MS patients, suggesting a strong link. A groundbreaking study by Bjørnevik et al. (2022) followed over 10 million U.S. military personnel for 20 years and confirmed that EBV infection dramatically increases MS risk. The study found that people infected with EBV were 32 times more likely to develop MS compared to those who weren’t, with the risk peaking if infection occurs later in life, such as during adolescence.

EBV may trigger MS by confusing the immune system, causing it to attack the body’s own nerve-protecting myelin. Interestingly, vitamin D may help by lowering EBV-related antibodies, potentially reducing this risk. Other viruses, like human herpesvirus 6, might also play a role, but EBV remains the most studied culprit.

What This Means for You: If you’ve had mono, especially as a teen, your MS risk may be higher. Supporting your immune system with adequate vitamin D, a healthy diet, and stress management can help mitigate this risk and promote overall health.

Gender and Hormones: Why Women Face Higher Risk

MS strikes women about three times more often than men, and hormones are a key reason why. A 2018 study by Ysrraelit and Correale explains how sex hormones shape immune responses in MS. Estrogens and progesterone, which surge during pregnancy, act like natural immune soothers, often reducing MS relapses. This is why many women with MS feel better during pregnancy but may experience flare-ups after giving birth when hormone levels drop.

On the flip side, prolactin, a hormone that rises during breastfeeding, can sometimes worsen MS by boosting inflammation. In men, low testosterone is linked to greater disability, as testosterone has its own calming effect on the immune system. Hormonal shifts during puberty, menopause, or even from birth control pills can also influence MS risk or symptom severity, particularly in women. Vitamin D enhances the protective effects of estrogens and progesterone, which may explain why women often benefit more from vitamin D supplements.

What This Means for You: If you’re a woman, hormonal changes throughout life may affect your MS risk or symptoms. Working with your doctor to monitor hormone health and ensure adequate vitamin D levels can support your immune system, especially during key life stages.

Lifestyle Choices: Power in Your Hands

Your daily habits can either raise or lower your MS risk, offering a powerful way to take control. Here are some key lifestyle factors:

• Obesity: Carrying excess weight, especially in adolescence, increases MS risk by reducing vitamin D availability and fueling inflammation. Maintaining a healthy weight through balanced eating and exercise can help.

• Smoking: Cigarette smoking worsens MS risk and progression by increasing oxidative stress and immune dysfunction. Quitting smoking is one of the most impactful steps you can take.

• Diet: Eating foods rich in vitamin D (like fatty fish, fortified dairy, or cod liver oil) and anti-inflammatory nutrients (like fruits, vegetables, and omega-3s) can lower MS risk. Diets high in processed foods or unhealthy fats, however, may increase it.

• Outdoor Time: Spending time outside during childhood and adolescence boosts vitamin D production and is linked to a lower MS risk. Even as an adult, safe sun exposure (15–30 minutes a few times a week, depending on skin type) can help.

• Infections and Hygiene: The “hygiene hypothesis” suggests that exposure to common infections or parasites in childhood strengthens immune regulation, potentially reducing MS risk. Conversely, overly sterile environments might increase autoimmune disease risk.

What This Means for You: Small changes—like eating nutrient-rich foods, staying active, quitting smoking, and enjoying time outdoors—can make a big difference in reducing MS risk or managing symptoms.

Bringing This Together

MS risk builds over a lifetime, shaped by a dynamic interplay of genes, environment, and lifestyle. Imagine it like a puzzle: a genetic predisposition (like an immune system gene) might be one piece, but it needs others—like low vitamin D, a late EBV infection, or unhealthy habits—to complete the picture. Critical periods, such as pregnancy, childhood, and adolescence, are especially important because they shape immune system development. For example, a mother’s vitamin D status during pregnancy can influence her child’s MS risk decades later.

Protective factors, like high vitamin D levels, a healthy weight, and outdoor activities, can offset risks, potentially delaying or preventing MS. For those already diagnosed, addressing these factors can reduce relapses and improve quality of life. The key is that no single factor acts alone—everything from your genes to your diet interacts in complex ways.

Take Charge with Practical Steps

You can’t change your genes or past infections, but you can tackle modifiable factors to lower your MS risk or manage the disease. Here’s how to get started:

• Check Your Vitamin D: Ask your doctor to test your vitamin D levels (aim for 30–60 ng/mL). If low, they may suggest Vitamin D supplements or vitamin D-rich foods like salmon or fortified milk.

• Embrace Safe Sun Exposure: Spend time outside when UVB rays are strongest (midday, spring to summer) to naturally boost vitamin D. Follow guidelines for your skin type to avoid sunburn.

• Eat for Immune Health: Focus on an anti-inflammatory diet with plenty of fruits, vegetables, whole grains, and healthy fats. Limit processed foods and sugary drinks.

• Move Your Body: Regular exercise, like walking, yoga, or swimming, supports a healthy weight and reduces inflammation. Aim for at least 150 minutes of moderate activity per week.

• Kick the Smoking Habit: If you smoke, seek support to quit—your immune system and overall health will thank you.

• Manage Stress: Chronic stress can worsen inflammation. Try mindfulness, meditation, or talking to a counselor to keep stress in check.

Empower Yourself with the MS PhysiKit Lifestyle Module

Whether you’re at risk for MS or living with it, the MS PhysiKit Lifestyle Toolkit is your partner in taking control. This evidence-based program offers guidance on nutrition, exercise, vitamin D optimisation, and stress management, that you can tailor to your unique needs. By addressing the modifiable factors through year-to-year changes, you'll be empowered to live healthier and feel your best.

🔗 Explore the MS PhysiKit to learn how simple, science-backed changes can transform your MS journey.

_References

_{Bjørnevik, K., Cortese, M., Healy, B. C., Kuhle, J., Mina, M. J., Leng, Y., Elledge, S. J., Niebuhr, D. W., Scher, A. I., Munger, K. L., & Ascherio, A. (2022). Longitudinal analysis reveals high prevalence of Epstein-Barr virus associated with multiple sclerosis. Science, 375(6578), 296–301. https://doi.org/10.1126/science.abj8222}

_{International Multiple Sclerosis Genetics Consortium & Wellcome Trust Case Control Consortium 2. (2011). Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis. Nature, 476(7359), 214–219. https://doi.org/10.1038/nature10251}

_{Pierrot-Deseilligny, C., & Souberbielle, J.-C. (2017). Vitamin D and multiple sclerosis: An update. Multiple Sclerosis and Related Disorders, 14, 35–45. https://doi.org/10.1016/j.msard.2017.03.014}

_{Ysrraelit, M. C., & Correale, J. (2018). Impact of sex hormones on immune function and multiple sclerosis development. Immunology, 156(1), 9–22. https://doi.org/10.1111/imm.13004}