Vitamin D Deficiency and Constipation

Are you wondering how vitamin D deficiency can lead to constipation? How could a vitamin that functions in bone health and calcium absorption cause constipation?

As we’ve been discussing in a few previous posts:

Constipation…beyond fiber, fluids and movement

3 Patterns of Constipation after Gastric Sleeve & Bypass

Constipation improves with a surprising starch

We are trying to identify different areas that can contribute to chronic constipation after gastric sleeve and gastric bypass surgery.

Sometimes increasing fiber & fluid may not resolve your constipation. For some, it may worsen your symptoms. Therefore, we are exploring different approaches to improve constipation.

You may be asking, how can vitamin D deficiency cause constipation?

Let’s take a look at the mechanism of action of this vitamin.

Mechanism of Action

Vitamin D is an essential nutrient that we can take from sunlight. Sunlight touches our skin, its ultraviolet B (UVB) rays hit cholesterol in our skin cells. It provides the energy to synthesize vitamin D within the body.

The inactive form of vitamin D produced by sunlight will then go to the liver and kidneys. They are responsible for converting it the into active vitamin D.

Problems linked to Vitamin D deficiency

Well known issues linked with Vitamin D deficiency.

Inflammatory bowel disease (IBD)
Inflammatory bowel syndrome (IBS)
Obesity
Depression
Seasonal affective disorder (SAD) especially in winter

Study Linked to Functional Constipation and Vitamin D

This study in 2019, the World Journal of Gastroenterology it was titled, “Chronic functional constipation, strongly linked to vitamin D deficiency.” So this was with patients with motility disorders.

Although this study lacks the factor of obesity, it covers the surveys related to the participants quality of life. Again, these factors correlate with vitamin D deficiency.

People with digestive issues may suffer with depression and anxiety. Consequently disturbing their quality of life.

This study observes 86 patients with functional constipation and motility disorders and 86 healthy people.

Although it is a small study they did observe low vitamin D levels in those which chronic constipation.

Protocols for Vitamin D Levels in the Study

Let’s discuss standard reference ranges for Vitamin D.

Reference range: 30 – 100 ng/ml
Deficient: <20 ng/ml
Insufficient: 20 – 29 ng/ml
Sufficient: >30 ng/ml

In Functional Medicine we try to optimize levels for protection and prevention from disease. The ideal reference range used for vitamin D typically would be >50 ng/ml but <80 ng/ml.

What did the study find?

Average levels of Vitamin D in those with constipation

Among diseased ➔ 14.6 ng/ml
Among controls ➔ 28.6 ng/ml

Pretty significant!

In the functional medicine world. Both the controls and diseased would be considered deficient.

Clinicians Perspective and BMI

If vitamin D deficiency is common in the obese population, why weren’t they included? Participants of this study fall in the range of normal BMI.

BMI cut-off Values

Underweight: < 18.5 kg/m²
Normal: 18.5 – 24.9 kg/m²
Overweight: 25 – 29.9 kg/m²
Obese: > 30 kg/m²

Unfortunately, this study only had participants within normal BMI ranges.

Among diseased ➔ 23.7 kg/m²
Among controls ➔ 24.6 kg/m²

It might be interesting to see the effects of Vitamin D on chronic functional constipation among obese.

Although bariatric surgery is the best option for those struggling with obesity. “Normal” or “healthy” BMI may not be attained.

In reality, many bariatric patients cannot attain or maintain BMI in normal ranges. Instead, they maintain beautifully in the overweight range of BMI post gastric sleeve & bypass surgery.

At no surprise, many clinicians don’t rely on standard BMI ranges for all guidance.

Instead, looking at the big picture is needed. If you’ve lost one hundred pounds post gastric sleeve & bypass surgery. You’re likely healthier than before. Even if you aren’t in the standard “healthy” BMI range.

Season of Conducting the Study

Another study flaw, the study was conducted in the summer when the sun shines at its peak. Many experience low vitamin D during the winter months only. It would be interesting to continue the study through the winter months. This would provide an annual perspective.

Genetic Links of the Study

This study didn’t include some important information.

Genetics!

Single nucleotide polymorphisms (SNPs) of vitamin D are pretty impactful. They are responsible for Vitamin D’s:

Absorption
Metabolism
Utilization
Conversion to it’s active form

These SNPs include:

VDR(Vitamin D receptor)
CYP2R1 (cytochrome p450 enzyme)
GC

It is unclear whether the diseased group or the control group have any of the genetics SNPs that impact vitamin D.

Points to Notice

So what can you do to improve your vitamin D status and gastric symptoms.

Focus on collaborating with your bariatric team to check your vitamin D levels
Spend at least 15 to 20 minutes in the sun without sunscreen daily
Increase vitamin D rich foods
Learn your genetics
Correct fat malabsorption

Again, constipation is complex. It may require multiple areas of correction to improve daily bowel movements.

In conclusion, although this study has flaws. Optimizing your vitamin D may be beneficial. Although it’s unlikely to resolve constipation on its own. Combined with optimizing gut health, thyroid and bile flow may be just what you need!

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