Vitamin D Supplementation Boosts Quality of Life in IBS Without Easing Symptoms

Kelly C. Cara

Credit: ResearchGate

Taking oral vitamin D supplementation may improve vitamin D status and quality of life in adults with irritable bowel syndrome (IBS), new moderate-level evidence suggests.¹ Yet, the study did not find vitamin D supplements improved symptom severity.

“Our results should come as no surprise to those in the field; IBS is a multifaceted disease and vitamin D, much like other classic nutrients, exhibits innate complexities in its actions and interactions, influencing countless biological mechanisms,” wrote investigators, led by Kelly C. Cara, from Friedman School of Nutrition Science and Policy, Tufts University, in Boston. “It is important to note that international recommendations for adequate serum 25(OH)D status, including those from the Endocrine Society, are based on bone-related outcome measures and not IBS.”

Research has revealed 82% of people with IBS are insufficient or deficient in serum 25-hydroxyvitamin D (25(OH)D) levels.² Despite the common deficiency, it is not known if increasing vitamin D levels will improve symptom severity and quality of life.¹

Investigators conducted a systematic review and meta-analysis to see if changes in vitamin D levels impact symptom severity and quality of life in adults with IBS. The team leveraged data from MEDLINE, Cochrane Central Register of Controlled Trials, Global Health, EMBASE, and Web-of-Science databases up to August 12, 2024, and ultimately included 12 studies (RCT, n = 7; Single-arm interventions, n = 3; Mendelian randomization, n = 2).

Among the 12 studies, 7 study populations had deficient (< 20 ng/mL), and 3 had insufficient (21 – 29 ng/mL) baseline serum 25(OH)D levels. Mean baseline serum 25 (OH) D levels for intervention study groups ranged from 11.68 to 21.33 ng/mL.

The randomized controlled trials (RCTs) and single-arm intervention studies had between 40 – 135 participants, aged 18 – 75 years. The 2 Mendelian randomization studies ranged from 187,028 to 496,946 participants and did not report ages. Studies were conducted in various countries, including Iran (n = 4), Egypt (n = 2), Pakistan (n = 1), China (n = 2), the UK (n = 2), and the US (n = 1).

Participants in the randomized controlled trials received 3,000 IU daily to 50,000 IU biweekly vitamin D dosages. The change in vitamin D levels was measured after 6 – 26 weeks.

Meta-analyses of these randomized controlled trials showed patients on oral vitamin D had increased 25(OH)D levels compared with placebo (pooled mean difference, 20.33; 95% confidence interval [CI], 12.91 to 27.74 ng/mL). Taking oral vitamin D significantly improved quality of life scores in participants deficient in serum 25(OH)D levels at baseline (3.19; 95%, CI 2.14 to 4.24).

However, participants had a nonsignificant reduction in IBS symptom severity (-55.26; 95% CI, -55.26 to 3.48). Subgroup analyses also produced similar results among populations with deficient vitamin D status at baseline (-31.22; 95% CI, -65.61 to 3.18) and with overweight BMI status (−22.23; 95% CI, –65.03 to 20.56).

In contrast, when investigators examined the 3 single arm intervention studies, they noted vitamin D supplements improved IBS symptom severity. Among 97 analyzed patients, 56.7% on vitamin D experienced complete relief from IBS symptoms, including abdominal fullness, bloating, heartburn, constipation, and diarrhea. Moreover, 36.1% demonstrated considerable improvement, and 6.2% had moderate relief.

Another single-arm intervention study found 12 weeks of vitamin D supplementation resulted in 97.5% of participants repleting vitamin D status, 47.5% with no IBS symptoms, and 52.5% with a partial relief of symptoms. Participants with no IBS symptoms at follow-up had significantly greater 25(OH)D levels compared with those who only experienced partial relief (P = .01).

The third single-arm intervention study also found a similar finding: vitamin D not only increased their 25(OH)D levels (P < .0001) but improved their symptoms. Participants on placebo had a significantly reduced number of bowel movements a day (P < .0001).

As for the Mendelian randomization studies, one study found there was no causal association between serum 25(OH)D levels and genetically predicted risk of IBS, as seen by inverse variance weighted (P = 0.94), MR Egger (p = 0.95), and weighted median (P = .76). Another study found vitamin D intake was not causally associated with IBS (P > .01) and serum 25(OH)D was not causally associated with IBS (P > .05).

“It is likely that (if present) vitamin D asserts a threshold effect; therefore, consideration of participant baseline status in the inclusion and exclusion criteria of future trials can help ensure accuracy of the response to treatment with vitamin D,” investigators wrote. “Future RCTs with sufficient power are greatly needed to fully elucidate the effects of vitamin D supplementation, past repleting inadequate or deficient serum 25(OH)D levels, in adults with IBS.”

References

1. ^{Cara KC, Taylor SF, Alhmly HF, Wallace TC. The effects of vitamin D intake and status on symptom severity and quality-of-life in adults with irritable bowel syndrome (IBS): a systematic review and meta-analysis. Crit Rev Food Sci Nutr. Published online September 5, 2024. doi:10.1080/10408398.2024.2400603}
2. ^{Khayyat Y, Attar S. Vitamin D Deficiency in Patients with Irritable Bowel Syndrome: Does it Exist?. Oman Med J. 2015;30(2):115-118. doi:10.5001/omj.2015.25}