Asthma reduced by 4,400 IU of Vitamin D while pregnant - RCT and video Weiss
Lessons Learned from an RCT on Prenatal Vitamin D and Asthma - interview Feb 2025
Summary by GLASP AI
(00:00-01:34) Dr. Scott Weiss, a Harvard Medical School professor and top biomedical researcher, began studying vitamin D's role in asthma after identifying the vitamin D receptor gene's link to childhood asthma through genetic and observational studies.
(03:07-04:26) Vitamin D has both endocrine effects
(bone health, measured through serum levels) and developmental effects
(immune system, organ development, measured in tissue levels).
It plays a crucial role throughout pregnancy, from implantation to postnatal immune function.
(04:26-08:49) The VDART trial enrolled pregnant women *(10-18 weeks gestation) at high risk for having asthmatic children, randomizing them to receive either 4,400 IU or 400 IU vitamin D daily. Results showed a 20% reduction in childhood asthma, with a p-value of 0.051.
(13:09-15:13) The trial faced three main limitations: insufficient vitamin D dosing *(only 75% reached target levels), late pregnancy initiation, and the presence of vitamin D in both control and treatment groups at baseline. When these factors were accounted for through meta-analysis and stratification, the reduction in asthma risk increased to 50%.
(27:32-29:08) Molecular and genetic evidence showed vitamin D influences fetal lung development by increasing sphingolipid levels, which are necessary for airway and immune system development. This provides mechanistic support for the clinical findings.
(31:50-33:14) Vitamin D deficiency during pregnancy may be a significant contributor to health disparities, particularly affecting African-American communities. Current recommendations *(600 IU) are
- far below what experts like Dr. Weiss suggest *( 6,000 IU minimum ).
(34:34-38:16) Pregnancy creates a dramatically increased physiological need for vitamin D, with 5-20 times higher requirements than non-pregnant state, due to fetal development needs and immune system modulation.
(38:57-41:03) Dr. Weiss's team conducted mouse studies to measure vitamin D levels in various tissues compared to serum levels, as tissue measurements aren't possible in living humans. This research aims to better understand the relationship between serum and tissue vitamin D levels.
(41:41-44:11) Dr. Weiss advocates for using "totality of evidence" rather than relying solely on randomized controlled trials for medical guidelines. He notes that BMI significantly affects vitamin D's effectiveness - women with normal BMI at pregnancy start showed better outcomes than obese women.
(46:28-49:22) For future trials, Dr. Weiss recommends: enrolling women earlier in pregnancy *(4-5 weeks vs. 10-18 weeks), using higher vitamin D doses *(6,000-8,000 IU vs. 4,400 IU), and ensuring greater baseline difference between control and treatment groups. He notes VDART's results likely apply to general population.
(50:04-52:54) While a new randomized controlled trial would cost approximately $10-12 million , Dr. Weiss considers this cost-effective given the potential lifetime savings from preventing pregnancy complications and childhood health issues. The main challenge is finding initial funding for such a study.
Asthma reduced 60% by daily 4,400 IU of Vitamin D while pregnant – RCT Feb 2024
Association of Prenatal Maternal and Infant Vitamin D Supplementation with Offspring Asthma
Ann Am Thorac Soc Vol 21, No 2, pp 279–286, DOI: 10.1513/AnnalsATS.202306-504OC
Lourdes G. Ramirez 1,2, Kathleen Lee-Sarwar1,2, Rachel S. Kelly1, Scott T. Weiss 1, and Augusto A. Litonjua3
1Channing Division of Network Medicine and
2Division of Allergy and Clinical Immunology,
both 1&2: Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts;
3Division of Pediatric Pulmonary Medicine, Golisano Children’s Hospital at Strong, University of Rochester Medical Center, Rochester, New York
Rationale: The role and timing of vitamin D supplementation in the prevention of asthma has not been fully elucidated.
Objective: To describe the association between prenatal and postnatal vitamin D with offspring asthma outcomes in participants of the Vitamin D Antenatal Asthma Reduction Trial.
Methods: We classified 748 mother-offspring pairs into four groups based on the mother’s randomization to receive high-dose versus low-dose (4,400 IU vs. 400IU) vitamin D supplementation during pregnancy and the offspring parent-reported highdose versus low-dose (>400 IU vs. <400 IU) vitamin D supplementation as estimated by intake of vitamin D drops or infant formula. We used logistic regression to test the association of the four vitamin D exposure groups—“mother-low/infant-low (reference),” “mother-high/infant-high,” “mother-high/infant- low,” and “mother-low/infant-high”—with offspring asthma and/or recurrent wheeze at age 3 years, active asthma at age 6 years, and atopic asthma at age 6 years.
Results: The risk of asthma and/or recurrent wheeze at 3 years was lowest in the mother-high/infant-low group (adjusted odds ratio vs. mother-low/infant-low, 0.39; 95% confidence interval, 0.16-0.88, P = 0.03). When stratifying by history of exclusive breastfeeding until age 4 months, the protective effect in the mother-high/infant-low group was seen only among exclusively breastfed infants (odds ratio vs. mother-low/infant-low, 0.19; 95% confidence interval, 0.04-0.68; P = 0.02). We did not observe any significant associations with active or atopic asthma at age 6 years.
Conclusions: We observe that high-dose prenatal and low-dose postnatal vitamin D supplementation may be associated with reduced offspring asthma or recurrent wheeze by age 3 years, but this association may be confounded by the protective effect of breastfeeding.
📄 Download the PDF from VitaminDWiki
VitaminDWiki - 6 ways to reduce asthma risk even more:
Higher dose (author reccomends 6,000 IU)
Provide even higher doses for mothers who smoke
Start before she typically realizes that she is pregnant
- preferably start BEFORE conception (author recommends 4-5 weeks after)
Use a loading dose
Use weekly dosing in place of daily
Also use Vitamin D Receptor activator
VitaminDWiki – Overview Asthma and Vitamin D contains
{include}
9 Relevant pages in VitaminDWiki
Those with Asthma or COPD had half the response to Vitamin D – March 2020
Vitamin D Deficiency is a Strong Predictor (4X) of Asthma in Children – Oct 2012
Less Asthma if mother took vitamin D while pregnant – Oct 2023
Asthma reduced 31 percent when Omega-3 taken during pregnancy – RCT Dec 2016
Asthma in 3 year olds decreased somewhat with 4,000 IU during pregnancy – RCT Jan 2016
Smoking while pregnant lowers vitamin D and increases child asthma by 3.6 X – Aug 2011
- Smoking typically reduces vitamin D levels by 10 ng/ml