What triggers systemic lupus in people is far from being fully understood. But science seems to be getting there, which is why managing lupus is easier now than it was 10-years ago. 
On the other hand, treating lupus hasn’t changed much during the last 50-years. It still includes taking: 
- Anti-inflammatory drugs (NSAIDs)
So, we need to seek reversible risk factors that may change the course of the disease. These can include:
- Chemical compounds like air pollution
- Gut health
- Nutrient intake, such as vitamins and minerals
There is one vitamin in particular that science says is low in lupus patients. That plays a role in the manifestation, relapses, and development of this autoimmune condition.  This is what this article will cover – so read on to learn more.
The Vitamin/Hormone You Need
If you have lupus, chances are you’re Vitamin D deficient. 
Even more so if you:
- Live in Asia, South America, and Africa
- Located below 37° latitude
- Do not take Vitamin D supplementation
- Medicate with hydroxychloroquine, corticosteroids or immunosuppressants without Vitamin D supplementation
But you’re not alone.
Why is Vitamin D deficiency common in Lupus?
If you live with lupus, you’re told to avoid the sunshine. Or advised to use sunscreens with at least a sun protection factor of 50. 
This is because photosensitivity is a key feature of lupus. In which, exposure to sunlight can be a common trigger of flares. Not only as skin symptoms like rash or tingling but also as fatigue and joint pain. 
Sunshine is a source of pre-vitamin D3, which goes on to become Vitamin D3 at body temperature.  Vitamin D3 is otherwise known as “cholecalciferol.” It is the form of Vitamin D that the body produces.
The other form, “Ergocalciferol”, is in food. But Vitamin D3 seems to be the best source of raising your Vitamin D levels. With that said, Vitamin D3 is in animal products like egg yolks and oily fish. This is because animal skins also synthesis UV radiation to “cholecalciferol.” 
Still, around 80-90% of your Vitamin D levels will come from skin exposure to sunlight.  Thus, low levels of Vitamin D in lupus patients could be due to:
- Sun avoidance
- Use of sunscreens
- Taking sun-protective measures
- Spending too much time indoors
- Even foundation makeup
Not only is obesity a worldwide problem, but an issue for you with lupus.
One study claims that two-thirds of lupus patients are either overweight or obese. Both of which have higher levels of inflammation. On top of this, those that were obese had: 
- Poorer functional capacity
- Impaired health-related quality of life
- Higher levels of fatigue
- Worse pain
Obesity also appears to contribute to Vitamin D deficiency – irrespective of age. 
Vitamin D has a “lipophilic” nature. This means that it tends to combine with or dissolve in lipids or fats. Because of this trait, your body fat will keep some Vitamin D – even if you have low levels to begin with. 
Some suggest that being Vitamin D deficient could make you overweight.
Moderate to severe Vitamin D deficiency leads to higher “parathyroid hormone.” This promotes an influx of calcium into fat cells… thereby enhancing “lipogenesis” I.e., the process of fat storage. 
For instance, there was 57% less Vitamin D in the blood of obese subjects than the non-obese in one study. This was following the same time spent lay open to simulated sunshine. 
Alongside fat mass, systemic lupus predisposes you to lower lean muscle mass. Resulting in less muscle strength. Thus, playing a big part in the high levels of physical disability seen among lupus patients. 
Studies have shown that skeletal muscle can take up, retain and release the active form of Vitamin D. Put side-by-side to animal studies, this may make muscle, not blood, the largest pool of this metabolite in your body. 
For example, rickets is a condition seen in children with extreme and prolonging Vitamin D deficiency. Health professionals recognise muscle weakness as a symptom… and have done since the 1600s. 
This may explain why Vitamin D supplementations have a small, but positive, impact on global muscle strength. More so on your legs. 
It appears that your levels of Vitamin D will be lower if you take medications… and do not supplement with Vitamin D. 
There is a claim that low blood Vitamin D levels could be the consequence of your treatment plan. For example, glucocorticoids reduce the amount of calcium that your intestines take in. Accelerating the breakdown of the active forms of Vitamin D. Changing them to an inactive form and contributing to your low levels. 
That said, some studies support the idea that glucocorticoids cause low levels of Vitamin D in lupus patients. But other studies show low levels irrespective of steroid use. So, steroid use cannot fully explain Vitamin D deficiency in lupus patients. 
What’s more, a 2001 study found low levels of active Vitamin D as a result of medicating with hydroxychloroquine.  Yet, another paper reports that those taking this med appear to have higher levels.  Making it clear there is a need for more studies.
Your ethnicity may determine your Vitamin D levels also.
In fact, Anthropologists regard human skin colour as an evolutionary adaptation to sunlight. 
The theory is the closer your ancestors were to the equator, the darker their skin. This makes sense considering dark skin is protective against intense sunlight. Yet, having lighter skin will make it easier to absorb sunlight in colder climates.
Synthesis of Vitamin D in the skins is lower in blacks due to the greater amounts of melanin. This absorbs the UV wavelengths needed to produce Vitamin D3 in the skin. Thus, the darker your skin, the longer you will need to be out catching rays. 
It also means sun protection for those with light skin where sunlight is intense. Vitamin D supplements for those with dark skin everywhere else.
But we know that this isn’t the case anymore due to poor diets and lifestyles. Most people will reap rewards from Vitamin D supplements… especially if they have systemic lupus.
Vitamin D deficiency is a global public health problem in all age groups. 
Yet, low levels of Vitamin D are high in lupus patients. Due in part to photosensitivity issues or doctor’s orders to avoid the sun. As well as certain medications like prednisolone.
So, Vitamin D Supplementation with regular monitoring should be part of your health management plan. 
Even more so if you have dark skin, and/or are overweight. In this case, you will need to take higher doses of oral Vitamin D supplements.  This makes regular monitoring an important aspect.
That said, you cannot neglect the importance of body weight on Vitamin D levels. With fatty tissues and lean muscle mass being possible storage units for Vitamin D. One in which you can only access when they get broken down for energy needs.
This is simple for working muscle. As you use a body part, the muscles will release their Vitamin D stores. Yet, fat stores will continue building up unless you take steps to trim them. This involves eating better and exercising. 
So, if you take any message from this, take this. To improve your Vitamin D levels, and health, you need to be at a healthy weight. One built on through healthy eating and exercise.
If you do not understand the benefits of Vitamin D, keep an eye out for the upcoming article on that topic.