Fish oil or vitamin D during pregnancy can prevent croup

Taking fish oil and/or high-dose vitamin D supplements during pregnancy has a protective effect on childhood croup, demonstrated a randomised-controlled trial. If this finding is confirmed in other trials, 2 cheap micronutrient supplies could be efficiently used in the prevention of this common childhood respiratory disease.

Croup is a common respiratory disease among children aged 6 months to 3 years [1]. Mostly, the disease is mild, but it can lead to hospitalisations in severe cases [2,3]. Furthermore, it has been suggested in various studies that fish oil and vitamin D play a role in the development of the immune system and lung tissue [4,5]. Dr Nicklas Brustad (University of Copenhagen, Denmark) and co-investigators designed a randomised-controlled trial to examine the influence of fish oil and vitamin D supplements during pregnancy on the incidence of childhood croup [6]. Pregnant Danish women (n=623) were allocated to 1 of the 4 study arms:

• High-dose vitamin D (2800 IU/day) and fish oil;
• Standard-dose vitamin D (400 IU/day) and fish oil;
• High-dose vitamin D and placebo; or
• Standard-dose vitamin D and placebo.

After their birth, children were followed from age 0 to 3 years during planned visits to measure any experienced acute respiratory symptoms.

A significantly beneficial effect was observed for the intake of fish oil versus the intake of placebo on the risk of croup (11% vs 17%; HR 0.62; 95% CI 0.41–0.93; P=0.02). Interestingly, high-dose vitamin D significantly reduced the risk of croup compared with standard-dose vitamin D (11% vs 18%; HR 0.60; 95% CI 0.38–0.93; P=0.02). There was no interaction effect between the supplements on the risk of croup (P_interaction=0.56). “Observing the Kaplan-Meier curves, we can clearly see that there is no additive effect from 1 intervention to the other, suggesting that there is a ceiling effect of the 2 interventions (see Figure),” clarified Dr Brustad.

Figure: No evidence of interaction between supplements [6]



n-3 LCPUFA, fish oil supplement.

In summary, this is the first randomised-controlled trial to demonstrate protective effects of both fish oil and high-dose vitamin D supplements during pregnancy on the occurrence of childhood croup.

1. Bjornson CL, Johnson DW. Lancet. 2008;371:329–339.
2. Bjornson CL, et al. N Engl J Med. 2004;351:1306–1313.
3. Baiu I, Melendez E. JAMA. 2019;3219(16);1642.
4. Hewison M. Endocrinol Metab Clin North Am. 2010;39:365–379.
5. Calder PC. Lipids. 2001;36:1007–1024.
6. Brustad N, et al. Fish oil and vitamin D supplementations in pregnancy protect against childhood croup. Chronic and acute lung infections in children. OA2189, ERS International Congress 2022, Barcelona, Spain, 4–6 September.

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Posted on 30 October 2022