Vitamin D

Vitamin D holds a special place in my heart. I remember my Dad (Dr. Michael Stone) taking me to Dr. Michel Holick's (the Father of Vitamin D) office in Boston, MA in the mid-2000s. At the time, I thought my Dad and Dr. Hollick were the coolest, but my young self didn't fully comprehend how profound their conversation was. Now, as a Board-Certified Nutritionist working in the clinical field of perinatal nutrition, I am in awe of how crucial Vitamin D is and the role it plays in health and resilience (starting in utero). Dr. Holick's and Dr. Stone's work has informed our GrowBaby program from the very beginning. 

Vitamin D Basics 

Vitamin D3 is derived from ultraviolet-B (UV-B) sun exposure and then produced in the skin OR from dietary intake of foods like fatty fish, cod liver oil or egg yolk. Vitamin D2 is derived from dietary intake of fungal sources such as mushrooms and yeast. Skin production of Vitamin D accounts for about 80% the body's 25-OH D levels and dietary intake accounts for about 20%. 

Vitamin D - A Nutrient for Lifelong Health 

Fast Facts: 

• Vitamin D deficiency is common in pregnancy 

• Vitamin D is better absorbed with adequate magnesium and vitamin K

• Rates of deficiency are highest in winter - we recommend testing serum 25-OH D levels with every seasonal change.

• Based on randomized controlled trial (RCT) evidence- vitamin D supplementation is safe in pregnancy and improves vitamin D and calcium status.

• There is a 2%-11% of the variance in levels 25(OH)D depending on your genetics - you can find out more about your genetic predisposition & whether you need more vitamin D based on your genetics with our DNALife - GrowBaby gene test  

• BMI, age, environmental factors (sun exposure), ethnicity, geographical location, dietary intake, exposure to tobacco smoke all impact vitamin D levels. 

Vitamin D - A Crucial Nutrient in Preconception, Pregnancy and Postpartum

1. Decreases the risk of gestational diabetes 

2. Plays a key role in maternal insulin resistance 

3. Improves birth weight for baby (decreases small for gestational age)

4. Reduces the risk asthma and wheezing by 3 years old. 5. Vitamin D in breastfeeding is important, and women should consider supplementing with 6400 IUs of vitamin D to meet their baby's requirement of 400 IUs daily. 

6. Vitamin D levels can improve female and male infertility challenges. 

7. Vitamin D has a short half-life and daily supplementation may be favorable over intermittent high dose supplementation in pregnancy and breastfeeding. 

8. Salmon and Mackerel are food sources that are highest in Vitamin D. Fortified milk and eggs are also vitamin D rich foods.

9. 1,25(OH)2D or the vitamin D hormone, calcitriol is highest in pregnancy, >2–3 fold in the first weeks of pregnancy. Calcitriol functions as a classic steroid hormone (similar to thyroid or sex hormones). These levels are different than maternal 25-OH D serum levels which represent the main form of vitamin D in the fetus.

10. Maternal 25-OH D (25-hydroxyvitamin D) levels are ideally maintained between 50-75 nmol/L throughout pregnancy. Cord blood 25(OH)D concentrations are only about 50-80% of serum 25(OH)D concentrations. So, it is possible that individual maternal dosing of Vitamin D may need to increase. 

SOURCES

Karras et al, Metabolism. 2018 Sep;86:112-123

Schoos AM, et al, Children (Basel). 2019 Oct 21;6(10)

Stefan Pils, et al, Int J Environ Res Public Health. 2018 Oct; 15(10): 2241.