woman taking a vitamin D capsule from a pill box

Should I Take Vitamin D for MS? A Q&A with Ahna Crum, R.D.N.

By Kerry Weiss
Reviewed by Dana Cooper, M.D.
August 10, 2022

This article is part of a Q&A series in which a healthcare professional in our community answers your frequently asked questions.

You may have heard that taking vitamin D supplements can be helpful for some people with multiple sclerosis, and you may be wondering whether you should be getting more D in your diet—or even whether you should start taking supplements.

We brought these questions to Ahna Crum, registered dietitian, MS community expert, and fellow MS warrior. Here, Crum shares what you should know about vitamin D and MS, and also offers advice for safer supplementation.

How does vitamin D interact with MS?

Ahna Crum, R.D.N.: A deficiency of vitamin D is a known risk factor for developing MS. Research suggests that vitamin D helps to keep the immune system balanced as well as to control inflammation.

Could increasing my vitamin D intake help my MS?

AC: Maybe. Generally speaking, study findings suggest that many people living with MS have low levels of vitamin D. For those who are deficient, finding ways to bring D levels up to the normal, healthy range may help to prevent worsening of symptoms and progression of the disease.

Low levels of vitamin D can contribute to low energy and fatigue, which are common in people with MS. Vitamin D and adequate calcium intake are also important to protect bones against osteoporosis (loss of bone density). People taking steroids long term are at higher risk of osteoporosis.

However, when it comes to how vitamin D affects relapse rates of MS, research is inconclusive. Vitamin D has not been shown to be a cure for MS.

What are some ways to boost vitamin D levels?

AC: Fortunately, vitamin D levels can be increased through easy and inexpensive lifestyle modifications, like eating more vitamin D–rich foods, increasing your exposure to sunlight, and by taking commonly available supplements.

Vitamin D2 is the form of vitamin D we get from plant foods, while vitamin D3 is the form we get from animal-based food sources. Good food sources of vitamin D include seafood, mushrooms, egg yolks, dairy products, and fortified foods, such as cereal, orange juice, and plant-based milks.

Our skin also produces vitamin D3 when we’re exposed to the sun. If you don’t have a personal or family history of skin cancer, consider spending at least 10 minutes in the sun each day. Like all good things, enjoy sunshine in moderation, though, and be sure to protect yourself from excessive ultraviolet (UV) exposure by using SPF and covering up vulnerable areas.

These steps may also help further boost the positive effects of vitamin D:

  • Increasing calcium intake. Vitamin D and calcium work hand in hand to help promote healthy bones. And research has linked MS with low bone mineral density and osteoporosis. Green leafy vegetables are a great source of calcium—and they’re dairy free, if that matters to you.
  • Increasing magnesium intake. Magnesium is needed for vitamin D synthesis in the body. Most adults should aim to get anywhere between 310 and 420 milligrams of magnesium a day, according to guidelines from the National Institutes of Health. Excellent food sources of magnesium include whole grains, green leafy vegetables, legumes, nuts and seeds, avocados, and bananas. You can also talk to your doctor about magnesium supplements.
  • Eating more healthy fats. Vitamin D is fat-soluble, which means that some fat is needed to properly absorb the vitamin in the body. Fats found in fatty fish and olive oil are considered healthy.
  • Staying active. Research suggests exercise may increase vitamin D levels, potentially because of the release of stored vitamin D in fat cells.

When might it make sense to take vitamin D supplements?

AC: Supplements may be needed if a person needs more D than they can get from lifestyle modifications alone.

Diet and sun exposure can’t always make up for a vitamin D deficiency. There are many factors that can influence vitamin D levels, including the following:

  • Age
  • Weight
  • Skin color
  • Geographical location
  • Medication use
  • Gut health (which may affect fat absorption)
  • Liver and kidney health

Before taking a supplement, ask your doctor whether they recommend it for you. Your doctor may perform a blood test to see whether you’re deficient in vitamin D. Sometimes, if a person’s vitamin D levels are low, doctors will recommend high-dose vitamin D supplementation for a short period of time.

How much vitamin D should I take?

AC: When it comes to vitamin D, the amount you take is important. While studies have been inconclusive, some research suggests that moderate doses may help with disease progression and MS symptoms and have a beneficial effect on inflammation and the immune system.

However, new research suggests that excessive supplementation can actually be harmful in MS. Higher doses of vitamin D supplementation may have the following negative effects:

  • Promoting disease progression
  • Worsening disability
  • Spiking calcium to harmful levels
  • Increasing inflammation

If supplementing on a general basis, the recommended dietary allowance (RDA) for adults is between 600 and 800 international units daily. Some organizations recommend between 1,000 and 2,000 IU daily.

Talk to your doctor or dietitian for personalized guidance based on your lab work.

What’s the best way to take a vitamin D supplement?

AC: Because vitamin D is fat-soluble, some supplements are emulsified in oil for easier absorption by the body. These types of supplements can be taken alone, at any time, and on an empty stomach. Other forms of vitamin D are best absorbed when taken with a meal containing a moderate amount of healthy fat. You’ll know your supplement is an emulsion if the ingredients list includes oils.

Is vitamin D safe to take with MS medications?

AC: Vitamin D supplements haven’t been found to interact with the disease-modifying drugs prescribed for MS. However, other types of medications can affect the metabolism and absorption of vitamin D, including:

  • Antibiotics
  • Antifungals
  • Anti-epileptic medications
  • Stimulant laxatives
  • Chemotherapy agents
  • Glucocorticoids

Vitamin D can also interact with thiazide diuretics, potentially leading to unhealthily high calcium levels, known as hypercalcemia.

If you’re taking any of these types of medication, talk to your doctor before starting a vitamin D supplementation routine.

Are there any supplements I should take with vitamin D?

AC: Taking supplements for vitamin K2 and magnesium may be beneficial if you don’t get enough of these nutrients through your diet.

Vitamin D helps to increase calcium levels in the body, and vitamin K (specifically vitamin K2) tells it where to go to be used efficiently. Vitamin K2 is what enables calcium to bind to your bones. Without adequate K2, calcification can occur in veins and arteries, increasing the risk of heart and kidney disease. Magnesium also plays a key role in keeping the bones healthy and helps maintain vitamin D levels.

The RDA for magnesium is 400–420 milligrams for men and 310–320 milligrams for women. Whole grains, green leafy vegetables, legumes, nuts and seeds, avocados, and bananas are all magnesium-rich food sources.

As there’s not yet a recommended daily intake for vitamin K2, the best way to keep these levels maintained is through food choices. Chicken, egg yolk, sauerkraut, cheese, and the Japanese fermented soybean food known as natto are all rich in vitamin K2.

Depending on your individual lab work and need, a dietitian or physician can help guide your supplementation to make sure these nutrients are working properly together to promote optimal health.

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