Vitamin D and Multiple Sclerosis | Preventive Care?

Written by Dr. Steve Chaney on . Posted in current health articles, Vitamins and Health

Author: Dr. Stephen Chaney

 

vitamin d and multiple sclerosisA new study (Mokry et al, PLOS Medicine, DOI: 10.1371/journal.pmed.1001866, August 25, 2015) suggests that people who are genetically prone to low vitamin D levels are at increased risk of developing multiple sclerosis (MS). To understand the importance of this study and what it means for us, we need to first review what is already known about vitamin D and multiple sclerosis.

  • MS is an autoimmune disease in which the immune system attacks the myelin sheath that coats our nerves. Conceptually, that’s the equivalent of a fraying cord on a lamp. Eventually, the cord is going to start shorting out and the lamp won’t work very well. On a very basic level MS is similar. As our myelin sheath is damaged over time, our nervous system starts working less well.
  • The earliest evidence that vitamin D status might be associated with MS was the observation that the prevalence of MS was highest for people who lived in northern regions with little exposure to sunlight.
  • Numerous studies since then have shown that MS patients generally have lower 25-hydroxy vitamin D levels in their blood.

These studies clearly show an association between low vitamin D status and MS, but association does not prove causation. There are two limitations of association studies that significantly reduce their predictive value – reverse causation and confounding factors.Those are both somewhat highfalutin scientific terms, so let me put them in plain English – and in terms that are relevant to our discussion of vitamin D status and MS.

Reverse causation simple means that the MS might have caused low vitamin D status. For example, individuals with MS might spend less time outdoors because of their physical limitations. That would result in less sun exposure, which would decrease their blood levels of 25-hydroxy vitamin D.

A confounding factor would be something else that increased the risk for MS and happened to be associated with low vitamin D status. Suppose, for example, that exercise decreased the risk of MS. People who spend most of their time inside in front of a TV or computer screen would have low levels of exercise and low sun exposure. If it was the lack of exercise rather than the low vitamin D status that actually predisposed to MS, lack of exercise would be a confounding factor for any clinical study comparing vitamin D status with risk of developing MS.

 

What Can Genetics Tell Us About The Relationship Between Vitamin D and Multiple Sclerosis?

does-vitamin-d-prevent-msThe authors of this study had previously identified mutations in 4 genes that decrease blood levels of 25-hydroxy vitamin D (the most commonly used measure of vitamin D status). In this study(Mokry et al, PLOS Medicine, DOI: 10.1371/journal.pmed.1001866, August 25, 2015)they analyzed the frequency of those genetic mutations in 14,498 MS cases compared with 24,091 healthy controls. Their study showed:

  • Genetic mutations that decrease 25-hydroxy vitamin D levels are associated with a significant increase in the risk of developing MS.
  • Based on the relationship of those mutations with 25-hydroxy vitamin D levels, they calculated that every 50% increase in 25-hydroxy vitamin D levels was associated with a 50% decreased risk of developing MS.

This was a very large, well designed study. It has some limitations of its own, but because it used a genetic approach it largely avoids the concern about reverse causation and confounding factors. In short, this study strongly supports the conclusion from previous studies that low vitamin D status significantly increases the risk of developing MS.

The authors concluded “The identification of vitamin D as a causal susceptibility factor for MS may have important public health implications, since vitamin D insufficiency is common, and vitamin D supplementation is both relatively safe and cost effective.”

 

Is Vitamin D Supplementation Effective In Preventing And Treating MS?

Vitamin DThe authors of the study also concluded “These findings provide the rationale for further investigating the therapeutic benefits of vitamin D supplementation in preventing the onset and progression of MS.”

While more studies are still needed, the Nurses’ Health Study (Munger et al, Neurology, 62: 60-65, 2004) provides pretty convincing evidence that vitamin D supplementation can prevent the onset of MS. That study followed 187,563 nurses for at least 4 years, during which time 173 of them developed MS. The study showed that supplementation with 400 IU/day of vitamin D reduced the risk of developing MS by 40%.

The efficacy of vitamin D supplementation in preventing the progression of MS is much less well established. Several studies have shown that low vitamin D status is associated with higher levels MS relapse and more rapid progression of MS symptoms.However, studies of vitamin D supplementation conducted to date have been too small and too short in duration to be definitive.

What Is The Significance Of This Study?

On one hand MS is a very rare disease, affecting around 0.1% of the adult population. On the other hand, it is a debilitating disease. If something as simple as assuring adequate vitamin D status can reduce the risk of developing MS by 40-50%, it is an important public health measure, especially since 40% of the US population has insufficient blood levels of vitamin D (Looker et al, American Journal of Clinical Nutrition, 88: 1519-1527, 2008).

What Does This Study Mean For You?

SunWhat does this study mean for you and me? We already know that adequate vitamin D status is essential for building strong bones, and there is pretty good evidence that adequate vitamin D status is important for a strong immune system. Now we can add autoimmune diseases to the list. It is pretty clear that adequate vitamin D status is important for preventing MS. It may help prevent other autoimmune diseases as well.

One interesting wrinkle for MS is that it may be vitally important to assure adequate vitamin D in our younger years. Studies looking at people who grow up in northern latitudes and then move south and vice versa suggest that the risk of developing MS is much more strongly associated with sun exposure during the first 10-15 years of life than with sun exposure later in life.

It is, therefore, not just important that we assure adequate vitamin D status for ourselves. It may be even more important that we assure that our kids and grandkids have adequate vitamin D status.

The problem is that in today’s world we are told to slather industrial strength sunscreen on ourselves from head to foot before we leave the house and very few foods in nature provide significant amounts of vitamin D, so most of us rely primarily on vitamin D fortified dairy products and supplements to assure adequate intake of vitamin D. Click here for the latest RDA recommendations for vitamin D intake.

Some people do appear to need greater than RDA levels of vitamin D because they don’t metabolize vitamin D efficiently. They can have adequate intake of vitamin D, but their blood levels of 25-hydroxy vitamin D are low. I recommend that you ask your doctor to check your 25-hydroxy vitamin D levels at your next physical. If they are low, work out a vitamin D supplementation regimen with your doctor to bring your 25-hydroxy vitamin D levels into the optimal range.

 

The Bottom Line

  • A recent study showed that genetic mutations which decrease 25-hydroxy vitamin D levels are associated with a significantly increased risk of developing MS. Based on the relationship of those mutations with 25-hydroxy vitamin D levels, the investigators calculated that every 50% increase in 25-hydroxy vitamin D levels was associated with a 50% decreased risk of developing MS. This study strongly supports the conclusion from previous studies that low vitamin D status significantly increases the risk of developing MS.
  • An earlier Nurses’ Health Study has shown that supplementation with 400 IU/day of vitamin D decreases the risk of developing MS by 40%.
  • The authors of the most recent study concluded “The identification of vitamin D as a causal susceptibility factor for MS may have important public health implications, since vitamin D insufficiency is common, and vitamin D supplementation is both relatively safe and cost effective.” I agree.
  • While MS is a very rare disease, it can be devastating. This alone, is a good enough reason to be sure that you maintain adequate vitamin D status.
  • There is evidence that vitamin D status in our childhood years may be more important than our vitamin D status in later years for determining our risk of developing MS. It is, therefore, not just important that we assure adequate vitamin D status for ourselves. It may be even more important that we assure that our kids and grandkids have adequate vitamin D status.
  • While these and other studies demonstrate the health benefits of maintaining adequate vitamin D status, many Americans don’t do a good job of it. Government surveys show that 40% of Americans are deficient in vitamin D. That’s because we are continually being advised to slather on industrial strength sunscreen before we leave the house, and most naturally occurring foods are relatively poor sources of vitamin D.
  • While the evidence that vitamin D supplementation is effective for preventing MS is strong, evidence that vitamin D supplementation can slow the progression of MS is inconclusive at present. More and better studies are needed before we will have a definitive answer to this question.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Trackback from your site.

Leave a comment

Recent Videos From Dr. Steve Chaney

READ THE ARTICLE
READ THE ARTICLE

Latest Article

Can Plant-based Diets Be Unhealthy?

Posted September 10, 2019 by Dr. Steve Chaney

Do Plant-Based Diets Reduce Heart Disease Deaths?

Author: Dr. Stephen Chaney

 

plant-based diets vegetablesPlant-based diets have become the “Golden Boys” of the diet world. They are the diets most often recommended by knowledgeable health and nutrition professionals. I’m not talking about all the “Dr. Strangeloves” who pitch weird diets in books and the internet. I am talking legitimate experts who have spent their life studying the impact of nutrition on our health.

Certainly, there is an overwhelming body of evidence supporting the claim that plant-based diets are healthy. Going on a plant-based diet can help you lower blood pressure, inflammation, cholesterol and triglycerides. People who consume a plant-based diet for a lifetime weigh less and have decreased risk of heart disease, diabetes, and cancer.

But, can a plant-based diet be unhealthy? Some people consider a plant-based diet to simply be the absence of meat and other animal foods. Is just replacing animal foods with plant-based foods enough to make a diet healthy?

Maybe not. After all, sugar and white flour are plant-based food ingredients. Fake meats of all kinds abound in our grocery stores. Some are very wholesome, but others are little more than vegetarian junk food. If you replace animal foods with plant-based sweets, desserts, and junk food, is your diet really healthier?

While the answer to that question seems obvious, very few studies have asked that question. Most studies on the benefits of plant-based diets have compared population groups that eat a strictly plant-based diet (Seventh-Day Adventists, vegans, or vegetarians) with the general public. They have not looked at variations in plant food consumption within the general public. Nor have they compared people who consume healthy and unhealthy plant foods.

This study (H Kim et al, Journal of the American Heart Association, 8:e012865, 2019) was designed to fill that void.

 

How Was The Study Done?

plant-based diets studyThis study used data collected from 12,168 middle aged adults in the ARIC (Atherosclerosis Risk in Communities) study between 1987 and 2016.

The participant’s usual intake of foods and beverages was assessed by trained interviewers using a food frequency questionnaire at the time of entry into the study and again 6 years later.

Participants were asked to indicate the frequency with which they consumed 66 foods and beverages of a defined serving size in the previous year. Visual guides were provided to help participants estimate portion sizes.

The participant’s adherence to a plant-based diet was assessed using four different well-established plant-based diet scores. For the sake of simplicity, I will include 3 of them in this review.

  • The PDI (Plant-Based Diet Index) categorizes foods as either plant foods or animal foods. A high PDI score means that the participant’s diet contains more plant foods than animal foods. A low PDI score means the participant’s diet contains more animal foods than plant foods.
  • The hPDI (healthy plant-based diet index) is based on the PDI but emphasizes “healthy” plant foods. A high hPDI score means that the participant’s diet is high in healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) and low in animal foods.
  • The uPDI (unhealthy plant-based diet index) is based on the PDI but emphasizes “unhealthy” plant foods. A high uPDI score means that the participant’s diet is high in unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) and low in animal foods.

For statistical analysis the scores from the various plant-based diet indices were divided into 5 equal groups. In each case, the group with the highest score consumed the most plant foods and least animal foods. The group with the lowest score consumed the least plant foods and the most animal foods.

The health outcomes measured in this study were heart disease events, heart disease deaths, and all-cause deaths. Again, for the sake of simplicity, I will only include 2 of these outcomes (heart disease deaths and all-cause deaths) in this review. The data on deaths were obtained from state death records and the National Death Index. (Yes, your personal information is available on the web even after you die.)

 

Do Plant-Based Diets Reduce Heart Disease Deaths?

plant-based diets reduce heart deathsThe participants in this study were followed for an average of 25 years.

The investigators looked at heart disease deaths over the 25 years and compared people with the highest intake of plant foods to people with the highest intake of red meat and other animal foods. The results were:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

What Else Did The Study Show?

The investigators made a couple of other interesting observations:

  • The association of the overall diet with heart disease and all-cause deaths was stronger than the association of individual food components. This underscores the importance of looking at the effect of the whole diet on health outcomes rather than the “magic” foods you hear about on Dr. Strangelove’s Health Blog.
  • Diets with the highest amount of healthy plant foods were associated with higher intake of carbohydrates, plant protein, fiber, and micronutrients, including potassium, magnesium, iron, vitamin A, vitamin C, folate, and lower intake of saturated fat and cholesterol.
  • Diets with the highest amount of unhealthy plant foods were associated with higher intake of calories and carbohydrates and lower intake of fiber and micronutrients.

The last two observations may help explain some of the health benefits of plant-based diets.

 

Can Plant-Based Diets Be Unhealthy?

plant-based diets unhealthy cookiesNow, let’s return to the question I asked at the beginning of this article: “Can plant-based diets be unhealthy?” Although some previous studies have suggested that unhealthy plant-based diets might increase the risk of heart disease, this study did not show that.

What this study did show was that an unhealthy plant-based diet was no better for you than a diet containing lots of red meat and other animal foods.

If this were the only conclusion from this study, it might be considered a neutral result. However, this result clearly contrasts with the data from this study and many others showing that both plant-based diets in general and healthy plant-based diets reduce the risk of heart disease deaths and all-cause deaths compared to animal-based diets.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

There is one other subtle message from this study. This study did not compare vegans with the general public. Everyone in the study was the general public. Nobody in the study was consuming a 100% plant-based diet.

For example:

  • The group with the highest intake of plant foods consumed 9 servings per day of plant foods and 3.6 servings per day of animal foods.
  • The group with the lowest intake of plant foods consumed 5.4 servings per day of plant foods and 5.6 servings per day of animal foods.

In other words, you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet.

 

The Bottom Line

A recent study analyzed the effect of consuming plant foods on heart disease deaths and all-cause deaths over a 25-year period.

When the investigators looked at heart disease deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

A more subtle message from the study is that you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet. The people in this study were not following some special diet. The only difference was that some of the people in this study ate more plant foods and others more animal foods.

For more details on the study, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

UA-43257393-1