vitamin D deficiency

Which Nutrients Prevent Prenatal Depression?

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What Does This Study Mean For You?

Author: Dr. Stephen Chaney 

Yes, you read the headline correctly. Everyone talks about postnatal depression. But prenatal depression is also a “thing”, especially during the third trimester.

  • Worldwide, 4-20% of women experience some degree of depression during the third trimester – with pregnant women in high-income countries at the lower end (4-10%) of depression risk.
  • In contrast, the incidence of postnatal depression is 10-15%.

It is probably no coincidence that the incidence of depression is greatest during the third trimester and during the postnatal period.

  • The third trimester is the most difficult part of pregnancy for many women.
  • When a woman brings her baby home from the hospital her orderly life becomes chaotic.

But what role does nutrition play?

  • While not definitive, many studies suggest that supplementation with B vitamins, especially folic acid, B6, and B12; omega-3 fatty acids; vitamin D; and iron reduce the risk of postnatal depression.
  • However, there is much less information on which nutrients reduce the risk of prenatal depression.

Based on studies suggesting both iron and vitamin D deficiencies may negatively impact mental health, the authors of this study (JL Evanchuk et al, The Journal Of Nutrition. 154, 174-184, 2024) set out to determine whether iron and/or vitamin D deficiencies increase the risk of prenatal depression during the first trimester.

How Was This Study Done?

Clinical StudyThe authors recruited 2189 newly pregnant mothers from Calgary and Edmonton in Ontario Canada between 2009 and 2012. Participants in the study visited clinics in the area upon entry into the study; midway through the first, second, and third trimesters; and at multiple timepoints up to 3 months during the postpartum period.

In addition to the usual pregnancy wellness tests, participants filled out a 24-hour dietary recall and a Supplemental Intake Questionnaire to determine intakes of iron and vitamin D.

Note: The participants were all advised to take some form of prenatal supplement during the study. That’s because prenatal supplements are considered “the standard of care” for pregnant woman, so it would be considered unethical not to include a prenatal supplement in this study.

At the mid-point of the second trimester blood samples were drawn and analyzed for biomarkers of iron and vitamin D insufficiency. For iron the biomarkers were serum ferritin, soluble transferrin receptor, and hepcidin. For vitamin D, the biomarkers were 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and 3-epi-25-hydroxyvitamin D.

Iron deficiency was defined as serum ferritin levels <15 µg/L. Vitamin D insufficiency was defined as 25-hydroxyvitamin D levels < 75nmol/L. The other biomarkers were used to confirm these diagnoses.

Maternal depression was measured midway through the third trimester and ~3 months postpartum using 10-item questionnaire called the Edinburg Postnatal Depression Scale (EPDS). The EPDS ranks depression on a scale of 0 to 30, with a score of ≥13 considered an indication of likely depression.

The characteristics of the women enrolled in this study were:

  • Average age = 31.5
  • Average prepregnancy BMI = 23 (healthy weight).
  • Married or cohabitating with a partner = 97%.
  • Highly educated (college or postgraduate degree) = 68%.
  • Income above $70,000/year = 78%.
  • First child = 54%.
  • White = 80%.

Based on the Edinburg Depression Scale, probably depression for the 1822 women who completed the study was 5.6% during the third trimester and 4.4% 3 months postpartum.

Note: The low incidence of depression seen in this study was probably due to:

  • The women in this study were of high socioeconomic status and were receiving excellent healthcare.
  • The women in this study were taking prenatal supplements that provided both iron and vitamin D.

Which Nutrients Prevent Prenatal Depression? 

pregnant women taking vitaminsAs I mentioned when describing how the study was designed, all participants in this study were advised to take a prenatal supplement. Consequently:

  • 94% of the women in this study were taking a supplement containing iron with an average supplemental iron intake of 26 mg/day.
    • Note: The RDA for iron during pregnancy is 30 mg/day and most prenatal supplements provide 27 mg/day.
  • 68% of the women in this study were taking a supplement containing vitamin D, with an average supplemental vitamin D intake of 330 IU/day.
    • Note: The RDA for vitamin D during pregnancy is 600 IU/day, but most prenatal supplements provide far less than that.

When the investigators looked at iron and vitamin D status during the second trimester:

  • 63.3% of the women had adequate levels of both iron and vitamin D.
  • 14.8% of the women were low in vitamin D but had adequate iron levels.
  • 18.4% of the women were low in iron but had adequate levels of vitamin D.
  • 3.5% of the women were low in both iron and vitamin D.

RDAs are supposed to be enough to meet the nutrient requirements of 97-98% of healthy individuals, so it is perhaps surprising to see so many women with insufficient levels of iron (21.9%) and/or vitamin D (18.3%) in this study. This could be due to:

  • Insufficient intake.
    • This is a likely explanation for vitamin D because the supplements women were using in this study provided around half the recommended RDA for vitamin D and the women lived at a northern latitude where sun exposure makes a small contribution to vitamin D levels.
    • However, this is a less likely explanation for insufficient iron levels because the supplements provided 87% of the RDA for iron.
  • Inadequate RDAs. Studies like this one provide a rigorous test for the adequacy of existing RDAs. This study suggests the existing RDA for iron is adequate to meet the needs of ~80% of pregnant women, which is reassuring. However, it may need to be increased to reach the goal of meeting the iron requirements for 97-98% of pregnant women.

But the important question is whether the iron and vitamin D insufficiencies seen in this study mattered. The data suggested that they did.

  • For pregnant women with low iron, but adequate vitamin D levels in the second trimester, there was a small, but significant, increased risk of experiencing depression symptoms in the third trimester.
  • For pregnant women with low iron and vitamin D levels in the second trimester, the risk of experiencing depression symptoms in the third trimester increased by 2.2 points in the 30-point Edinburg Depression Scale.
    • This is equivalent to a 7.4% increased risk of depression from deficiencies of iron and vitamin D alone – and these are only 2 of at least 8 nutrients thought to be associated with maternal depression.

The authors concluded, “Maternal iron and vitamin D biomarkers, measured during midpregnancy, were independently associated with third trimester maternal depression symptoms…This investigation is one of the first to report on the combined adequacy of maternal iron and vitamin D status during pregnancy and its impact on maternal depression.

The novelty of this work reinforces the need to ask similar questions [with other nutrients and] in other pregnant populations. Future investigations should report on the status of multiple nutrients and explore their independent and combined impact on health outcomes of pregnant individuals and their children.”

What Does This Study Mean For You?

Questioning WomanDepression during pregnancy is bad for you. And because your fetus can sense your mood, it is bad for your baby. So, what should you do?

You can consult with your doctor about which antidepressants are safe to take during pregnancy. But the truth is there are no good choices. There are some antidepressants that are off limits. There are other antidepressants that appear to have little short-term risks, but we have no idea if there are long-term risks for your child.

So, what about natural approaches? Let’s start with nutrition.

The biggest takeaway from this study is that prenatal supplements may not be sufficient to prevent nutritional deficiencies that may cause prenatal depression for pregnant women.

  • This does not mean that every pregnant woman suffering prenatal depression should increase their iron and vitamin D levels.
  • However, if you are experiencing prenatal depression, you might want to ask your doctor about checking your iron and vitamin D status to determine if extra iron and/or vitamin D would be beneficial.

And to put this study into its proper perspective we need to remember that iron and vitamin D deficiencies are only two of many nutrients that may increase the risk of prenatal depression.

For example, in addition to iron and vitamin D, prenatal depression is associated with deficiencies of:

  • B vitamins, especially folate, B6 and B12. Most prenatal supplements provide the recommended RDA of folate for pregnant women, but not all contain RDA amounts of B6 and B12.
  • Calcium and magnesium. Very few prenatal supplements provide the recommended RDA for calcium and magnesium.
  • Omega-3s, especially DHA. Very few prenatal supplements provide DHA, and the few that do usually provide inadequate amounts of DHA.

So, when you are having your nutrition conversation with your doctor, you might not want to limit your conversation to iron and vitamin D.

Alternately, as I suggested last week’s issue of “Health Tips From the Professor”, you might wish to add a multivitamin supplement and an omega-3 supplement providing at least 300 mg of DHA plus EPA. This simple step would be sufficient to assure you have adequate levels of nutrients thought to be important for reducing the risk of prenatal depression.

And, of course, there are other lifestyle factors, as well. For example:

  • Diets high in highly processed foods are known to increase the risk of depression. And whole food, primarily plant-based diets decrease the risk of depression.
  • Overweight and obesity increase the risk of depression.
  • Regular exercise decreases the risk of depression.

The Bottom Line

A recent study looked at whether taking a prenatal supplement was sufficient to eliminate deficiencies of iron and vitamin D during pregnancy and whether deficiencies of these two nutrients during the second trimester of pregnancy increased the risk of depression during the third trimester.

When the investigators looked at iron and vitamin D status during the second trimester:

  • 14.8% of the women were low in vitamin D but had adequate iron levels.
  • 18.4% of the women were low in iron but had adequate levels of vitamin D.
  • 3.5% of the women were low in both iron and vitamin D.

But the important question is whether the iron and vitamin D insufficiencies seen in this study mattered. The data suggested that they did.

  • For pregnant women with low iron, but adequate vitamin D levels in the second trimester, there was a small, but significant, increased risk of experiencing depression symptoms in the third trimester.
  • For pregnant women with low iron and vitamin D levels in the second trimester, the risk of experiencing depression symptoms in the third trimester increased by 2.2 points in the 30-point Edinburg Depression Scale.
  • This is equivalent to a 7.4% increased risk of depression from deficiencies of iron and vitamin D alone.

When you consider that iron and vitamin D are just two of 8 or more nutrients thought to be important for preventing depression during pregnancy, the question becomes what you can do to decrease your risk of developing depression during pregnancy and after the birth of your child.

For more details about the study and what it means for you, 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.

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My posts and “Health Tips From the Professor” articles carefully avoid claims about any brand of supplement or manufacturer of supplements. However, I am often asked by representatives of supplement companies if they can share them with their customers.

My answer is, “Yes, as long as you share only the article without any additions or alterations. In particular, you should avoid adding any mention of your company or your company’s products. If you were to do that, you could be making what the FTC and FDA consider a “misleading health claim” that could result in legal action against you and the company you represent.

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

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About The Author

Dr. Chaney has a BS in Chemistry from Duke University and a PhD in Biochemistry from UCLA. He is Professor Emeritus from the University of North Carolina where he taught biochemistry and nutrition to medical and dental students for 40 years.  Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”. Dr Chaney also ran an active cancer research program at UNC and published over 100 scientific articles and reviews in peer-reviewed scientific journals. In addition, he authored two chapters on nutrition in one of the leading biochemistry text books for medical students.

Since retiring from the University of North Carolina, he has been writing a weekly health blog called “Health Tips From the Professor”. He has also written two best-selling books, “Slaying the Food Myths” and “Slaying the Supplement Myths”. And most recently he has created an online lifestyle change course, “Create Your Personal Health Zone”. For more information visit https://chaneyhealth.com.

For the past 45 years Dr. Chaney and his wife Suzanne have been helping people improve their health holistically through a combination of good diet, exercise, weight control and appropriate supplementation.

Vitamin D And ADHD

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Can ADHD Be Prevented?

Author: Dr. Stephen Chaney 

vitamin dIf you are pregnant, or of childbearing age, should you be supplementing with vitamin D? Increasingly, the answer appears to be yes.

  1. Based on blood 25-hydroxy vitamin D levels (considered the most accurate marker of vitamin D status):
    • 8-11% of pregnant women in the US are deficient in vitamin D (<30 nmol/L).
    • 25% of pregnant women have insufficient vitamin D status (30-49 nmol/L).

In short, that means around 1/3 of pregnant women in the US have insufficient or deficient levels of vitamin D. The effect of inadequate vitamin D during pregnancy is not just an academic question.

2) The Cochrane Collaboration (considered the gold standard for evidence-based medicine) has recently concluded that supplementation with vitamin D reduces the risk of significant complications during pregnancy.

3) Another recent study found that inadequate vitamin D status during pregnancy delayed several neurodevelopmental milestones in early childhood, including gross motor skills, fine motor skills, and social development.

If neurodevelopmental milestones are affected, what about ADHD? Here the evidence is not as clear. Some studies have concluded that vitamin D deficiency during pregnancy increases the risk of ADHD in the offspring. Other studies have concluded there is no effect of vitamin D deficiency on ADHD.

Why the discrepancy between studies?

  • Most of the previous studies have been small. Simply put, there were too few children in the study to make statistically reliable conclusions.
  • Most of the studies measured maternal 25-hydroxyvitamin D levels in the third trimester or in chord blood at birth. However, it is during early pregnancy that critical steps in the development of the nervous system take place.

Thus, there is a critical need for larger studies that measure maternal vitamin D status in the first trimester of pregnancy. This study (M Sucksdorff et al, Journal of the American Academy of Child & Adolescent Psychiatry, 60: 142-151, 2021) was designed to fill that need.

How Was The Study Done?

Clinical StudyThis study compared 1,067 Finnish children born between 1998 and 1999 who were subsequently diagnosed with ADHD and 1,067 matched controls without ADHD. There were several reasons for choosing this experimental group.

  • Finland is among the northernmost European countries, so sun exposure during the winter is significantly less than for the United States and most other European countries. This time period also preceded the universal supplementation with vitamin D for pregnant women that was instituted in 2004.

Consequently, maternal 25-hydroxyvitamin D levels were significantly lower than in most other countries. This means that a significant percentage of pregnant women were deficient in vitamin D, something not seen in most other studies. For example:

  • 49% of pregnant women in Finland were deficient in vitamin D (25-hydoxyvitamin D <30 nmol/L) compared to 8-11% in the United States.
  • 33% of pregnant women in Finland had insufficient vitamin D status (25-hydroxyvitamin D 30-49.9 nmol/L) compared to 25% in the United States.
  • Finland, like many European countries, keeps detailed health records on its citizens. For example:
    • The Finnish Prenatal Study collected data, including maternal 25-hydroxyvitamin D levels during the first trimester), for all live births between 1991 and 2005.
    • The Care Register for Health Care recorded, among other things, all diagnoses of ADHD through 2011.

Thus, this study avoided the limitations of earlier studies. It was ideally positioned to compare maternal 25-hydroxyvitamin D levels during the first trimester of pregnancy with a subsequent diagnosis of ADHD in the offspring. The long-term follow-up was important to this study because the average age of ADHD diagnosis was 7 years (range = 2-14 years).

Vitamin D And ADHD 

Child With ADHDDoes maternal vitamin D affect ADHD in the offspring? The answer to this question appears to be a clear, yes.

If you divide maternal vitamin D levels into quintiles:

  • Offspring of mothers in the lowest vitamin D quintile (25-hydroxyvitamin D of 7.5-21.9 nmol/L) were 53% more likely to develop ADHD than offspring of mothers in the highest vitamin D quintile (49.5-132.5 nmol/L).

When you divide maternal vitamin D levels by the standard designations of deficient (<30 nmol/L), insufficient (30-49.9 nmol/L), and sufficient (≥50 nmol/L):

  • Offspring of mothers who were deficient in vitamin D were 34% more likely to develop ADHD than children of mothers with sufficient vitamin D status.

The authors concluded: “This is the first population-based study to demonstrate an association between low maternal vitamin D during the first trimester of pregnancy and an elevated risk for ADHD diagnosis in offspring. If these findings are replicated, they may have public health implications for vitamin D supplementation and perhaps changing lifestyle behaviors during pregnancy to ensure optimal maternal vitamin D levels.”

Can ADHD Be Prevented? 

Child Raising HandI realize that this is an emotionally charged title. If you have a child with ADHD, the last thing I want is for you to feel guilty about something you may not have done. So, let me start by acknowledging that there are genetic and environmental risk factors for ADHD that you cannot control. That means you could have done everything right during pregnancy and still have a child who develops ADHD.

Having said that, let’s examine things that can be done to reduce the risk of giving birth to a child who will develop ADHD, starting with vitamin D. There are two aspects of this study that are important to keep in mind.

#1: The increased risk of giving birth to a child who develops ADHD was only seen for women who were vitamin D deficient. While vitamin D deficiency is only found in 8-11% of pregnant mothers in the United States, that is an average number. It is more useful to ask who is most likely to be vitamin D deficient in this country. For example:

  • Fatty fish and vitamin D-fortified dairy products are the most important food sources of vitamin D. Fatty fish are not everyone’s favorite and may be too expensive for those on a tight budget. Many people are lactose intolerant or avoid milk for other reasons. If you are not eating these foods, you may not be getting enough vitamin D from your diet. This is particularly true for vegans.
  • If you have darker colored skin, you may have trouble making enough vitamin D from sunlight. If you are also lactose intolerant, you are in double trouble with respect to vitamin D sufficiency.
  • Obesity affects the distribution of vitamin D in the body. So, if you are overweight, you may have low 25-hydroxyvitamin D levels in your blood.
  • The vitamin D RDA for pregnant and lactating women is 600 IU, but many multivitamin and prenatal supplements only provide 400 IU. If you are pregnant or of childbearing age, it is a good idea to look for a multivitamin or prenatal supplement that provides at least 600 IU, especially if you are in one of the high risk groups listed above.
  • Some experts recommend 2,000 to 4,000 IU of supplemental vitamin D. I would not recommend exceeding that amount without discussing it with your health care provider first.
  • Finally, for reasons we do not understand, some people have a difficult time converting vitamin D to the active 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D in their bodies. If you are pregnant or of childbearing age, it is a good idea to have your blood 25-hydroxyvitamin D levels determined and discuss with your health care provider how much vitamin D you should be taking. Many people need more than 600 IU to reach vitamin D sufficiency status.

#2: Maternal vitamin D deficiency has a relatively small effect (34%) on the risk of the offspring developing ADHD. That means assuring adequate vitamin D status during pregnancy should be part of a holistic approach for reducing ADHD risk. Other factors to consider are:No Fast Food

  • Low maternal folate and omega-3 status.
  • Smoking, drug, and alcohol use.
  • Obesity.
  • Sodas and highly processed foods.

Alone, each of these factors has a small and uncertain influence on the risk of your child developing ADHD. Together, they may play a significant role in determining your child’s risk of developing ADHD.

In closing, there are three take-home lessons I want to leave you with:

  1. The first is that there is no “magic bullet”. There is no single action you can take during pregnancy that will dramatically reduce your risk of giving birth to a child who will develop ADHD. Improving your vitamin D, folate, and omega-3 status; avoiding cigarettes, drugs, and alcohol; achieving a healthy weight; and eating a healthy diet are all part of a holistic approach for reducing the risk of your child developing ADHD.

2) The second is that we should not think of these actions solely in terms of reducing ADHD risk. Each of these actions will lead to a healthier pregnancy and a healthier child in many other ways.

3) Finally, if you have a child with ADHD and would like to reduce the symptoms without drugs, I recommend this article.

The Bottom Line 

A recent study looked at the correlation between maternal vitamin D status during the first trimester of pregnancy and the risk of ADHD in the offspring. The study found:

  • Offspring of mothers who were deficient in vitamin D were 34% more likely to develop ADHD than children of mothers with sufficient vitamin D status.

The authors concluded: “This is the first population-based study to demonstrate an association between low maternal vitamin D during the first trimester of pregnancy and an elevated risk for ADHD diagnosis in offspring. If these findings are replicated, they may have public health implications for vitamin D supplementation and perhaps changing lifestyle behaviors during pregnancy to ensure optimal maternal vitamin D levels.”

In the article above I discuss what this study means for you and other factors that increase the risk of giving birth to a child who will develop ADHD.

For more details 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.

 

Does Low Vitamin D Make You Weak?

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Why Is Vitamin D Research So Controversial?

Author: Dr. Stephen Chaney

vitamin dMillions of Americans lose muscle strength as they age, something called sarcopenia. This is not a trivial matter. Loss of muscle mass:

  • Leads to loss of mobility. It can also make it difficult to do simple things like lifting your grandchild or carrying a bag of groceries.
  • Increases your risk of falling. This often leads to serious fracture which increases your of dying prematurely. In fact, bone fractures increase your risk of dying by 3-fold or more. Even in those who recover their mobility and quality of life may never be the same.
  • Lowers your metabolic rate. This increases your risk of obesity and all the diseases that are associated with obesity.

Loss of muscle strength as we age is preventable. There are several things we can do to preserve muscle strength as we age, but in today’s article I will focus on the effect of vitamin D on muscle strength.

What if something as simple as preventing vitamin D deficiency could improve muscle strength as we age? That idea has been around for a decade or more. But, for reasons I will detail below, it has proven controversial. Let me start by sharing a recent study on vitamin D and muscle strength (N Aspell et al, Clinical Investigations in Ageing, volume 2019:14, pages 1751-1761).

How Was The Study Done?

Clinical StudyThe data for this study came from 4157 adults who were enrolled in the English Longitudinal Study On Aging. Participants in this study were all over the age of 60 and were still living in their own homes. The general characteristics of the study population were:

  • Their average age was 69.8 with 45% male and 55% female.
  • While 76% of the participants rated their health as “good” or above
    • 73% were overweight or obese.
    • 54% had a longstanding disease that limited mobility.
    • 29% were taking multiple medications.

Serum 25-hydroxy vitamin D levels were determined as a measure of vitamin D status.

  • 22% of the participants were vitamin D deficient (<30 nmol/L 25-hydroxy vitamin D).
  • 34% of the participants were vitamin D insufficient (between 30 and 50 nmol/L 25-hydroxy vitamin D).
  • 46% of the participants had adequate vitamin D status (>50 nmol/L 25-hydroxy vitamin D).

Muscle strength was assessed by a handgrip strength test with the dominant hand. Muscle performance was assessed with something called the short physical performance battery (SPPB), consisting of a walking speed test, a repeated chair raise test, and a balance test.

Does Low Vitamin D Make You Weak?

When the data on handgrip strength were analyzed:

  • Only 22% of the participants who had adequate vitamin D status had low handgrip strength.
  • 40% of participants who were vitamin D deficient had low handgrip strength. That’s almost a 2-fold difference.
  • Handgrip strength increased linearly with vitamin D status.
    • The relationship between vitamin D status and handgrip strength was highly significant (p<001).
    • The beneficial effect of vitamin D status on handgrip strength plateaued at around 55-69 nmol/L 25-hydroxy vitamin D. In other words, you need adequate vitamin D status to support muscle strength, but higher levels provide no additional benefit.

When the data on muscle performance (the SPPB test) were analyzed:

  • Only 8% of the participants who had adequate vitamin D status scored low on this test.
  • 25% of participants who were vitamin D deficient scored low on this test. That’s a 3-fold difference.
  • Muscle performance also increased linearly with vitamin D status.
    • The relationship between vitamin D status and muscle performance was also highly significant (p<001).
    • The beneficial effect of vitamin D status on muscle performance also plateaued at around 55-69 nmol/L 25-hydroxy vitamin D.

The authors concluded: “Vitamin D deficiency was associated with impaired muscle strength and performance in a large study of community-dwelling older people. It is generally accepted that vitamin D deficiency should be reversed to prevent bone disease. This strategy may also protect skeletal muscle function in aging.”

Why Is Vitamin D Research So Controversial?

ArgumentYou can be forgiven if you are saying to yourself: “I’ve heard this sort of thing before. I see a blog or headline claiming that vitamin D has a certain benefit, but it’s usually followed by later headlines saying those claims are false. Why can’t the experts agree? Is all vitamin D research bogus?”

The relationship between vitamin D status and muscle strength is no different.

  • Many, but not all, studies looking at the association between vitamin D status and muscle strength find that vitamin D status affects muscle strength.
  • However, many randomized, placebo-controlled clinical trials looking at the effect of vitamin D supplementation on muscle strength have come up empty.

A meta-analysis (L Rejnmark, Therapeutic Advances in Chronic Disease, 2: 25-37, 2011) of randomized, placebo-controlled clinical trials of vitamin D supplementation and muscle strength provides insight as to why so many of them come up empty.

The meta-analysis combined data from 16 clinical trials. The conclusions were similar to what other meta-analyses have found:

  • Seven of the studies showed a benefit of vitamin D supplementation on muscle strength. Nine did not.
  • When the data from all 16 studies were combined, there was only a slight beneficial effect of vitamin D supplementation on muscle strength.

However, it was in the discussion that the reason for these discrepancies became apparent. There were three major deficiencies in study design that were responsible for the discrepancies.

1) There was a huge difference in study design.

  • The subjects were of different ages, genders, and ethnicity.
  • The dose of vitamin D supplementation varied.
  • Different measures of muscle strength and performance were used.

Until the scientific and medical community agree on a standardized study design it will be difficult to obtain consistent results.Garbage In Garbage Out

While this deficiency explains the variation in outcomes from study to study, there are two other deficiencies in study design that explain why many of the studies failed to find an effect of vitamin D on muscle strength. I call this “Garbage In, Garbage Out”. Simply put, if the study has design flaws, it may be incapable of detecting a positive effect of vitamin D on muscle strength.

2) Many of the studies did not measure vitamin D status of the participants at the beginning of the study.

  • The results of the study described above show that additional vitamin D will be of little benefit for anyone who starts the study with an adequate vitamin D status.
  • In the study above 46% of the participants had adequate vitamin D status. This is typical for the elderly community. When almost 50% of the participants in a study have adequate vitamin D status at the beginning of a study it becomes almost impossible to demonstrate a beneficial effect of vitamin D supplementation on any outcome.

It is essential that future studies of vitamin D supplementation focus on participants who have low vitamin D status. Otherwise, you are almost guaranteeing a negative outcome.

3) Most of the studies ignored the fact that vitamin D status is only one of three factors that are essential for muscle strength.

  • In the case of muscle strength, especially in the elderly, the three essentials are vitamin D, protein, and exercise. All three are needed to maintain or increase muscle strength. Simply put, if one is missing, the other two will have little or no effect on muscle strength. Unfortunately, you cannot assume that exercise and protein intake are adequate in older Americans:
  • Many older adults don’t get enough exercise because of physical limitations.

Unfortunately, many clinical studies on the effect of vitamin D supplementation and muscle strength fail to include exercise and adequate protein intake in the study. Such clinical trials are doomed to failure.

Now you know why vitamin D research is so controversial. Until the scientific and medical community get their act together and perform better designed experiments, vitamin D research will continue to be controversial and confusing.

What Does This Mean For You?

Old Man Lifting WeightsLoss of muscle mass as we age is not a trivial matter. As described above, it:

  • Leads to loss of mobility.
  • Increases your risk of falling. This often leads to serious fractures which increase your risk of disability and death.
  • Lowers your metabolic rate, which increases your risk of obesity and obesity-related diseases.

So, what can you do prevent loss of muscle mass as you age? The answer is simple:

  • Aim for 25-30 grams of high-quality protein in each meal.
    • That protein can come from meat, fish, eggs, or vegetable sources such as beans, nuts, and seeds.
    • That doesn’t mean you need to consume an 8-ounce steak or a half chicken. 3-4 ounces is plenty.
    • However, it does mean you can’t subsist on green salads and leafy greens alone. They are healthy, but you need to include a good protein source if you are going to meet your protein needs.
  • Aim for 150 minutes of moderate intensity exercise per week.
    • At least half of that exercise should be resistance exercise (lifting weights, for example).
    • If you have physical limitations, consult your doctor and work with a physical therapist or personal trainer to design resistance exercises you can do.
    • Aim for a variety of resistance exercises. You will only strengthen the muscles you exercise.
  • Aim for an adequate vitamin D status.
    • Start with a multivitamin containing at least 800 IU of vitamin D3.
    • Because there is large variation in the efficiency with which we convert vitamin D to 25-hydroxy vitamin D, you should get your serum 25-hydroxyvitamin D tested on a yearly basis. Your health professional can tell you if you need to take larger amounts of vitamin D3.
    • This study suggests that a serum 25-hydroxy vitamin D level of 55-69 nmol/L is optimal, and higher levels provide no additional benefit. That means there is no need to take mega-doses of vitamin D3 unless directed by your health professional.

The Bottom Line 

A recent study looked at the effect of vitamin D status on muscle strength and performance in a healthy population with an average age of 69.

When they looked at handgrip strength:

  • Only 22% of the participants with an adequate vitamin D status had low handgrip strength.
  • 40% of participants who were vitamin D deficient had low handgrip strength. That’s almost a 2-fold difference.
  • Handgrip strength increased linearly with vitamin D status.

When they looked at muscle performance:

  • Only 8% of the participants with an adequate vitamin D status scored low on this test.
  • 25% of participants who were vitamin D deficient scored low on this test. That’s a 3-fold difference.
  • Muscle performance also increased linearly with vitamin D status.

The authors concluded: “Vitamin D deficiency was associated with impaired muscle strength and performance in a large study of community-dwelling older people. It is generally accepted that vitamin D deficiency should be reversed to prevent bone disease. This strategy may also protect skeletal muscle function in aging.”

If we look at the research more broadly, there are three factors that are essential for maintaining muscle mass as we age: exercise, protein, and vitamin D. Therefore, my recommendations are to:

1)  Aim for 25-30 grams of high-quality protein in each meal.

2) Aim for 150 minutes of moderate intensity exercise per week. At least half of that exercise should be resistance exercise.

3) Aim for an adequate vitamin D status (>50 nmol/L of serum 25-hydroxy vitamin D). A good place to start is with a multivitamin providing at least 800 IU of vitamin D3.

For more details on my recommendations and a discussion of why studies on vitamin D supplementation are often confusing, 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

 

Health Tips From The Professor