For decades, we have known about the need for calcium in the diet and its importance in the physiology of growth and skeletal maturity, as well as its role in assuring functionality of smooth muscle, like the heart and intestines. Our study of calcium has led us to the realization that adequate calcium absorption from the diet requires Vitamin D, and that this can only be made in sufficient quantities when an individual has access to sufficient sunlight.
Despite our knowledge of the need for and mechanism of action of both calcium and Vitamin D, research is showing that more and more children are suffering from Vitamin D deficiency, which will inevitably lead to calcium deficiency and such well known maladies as rickets and osteoporosis.
Back in June of 2008, we looked at new data suggesting that both Vitamin D deficiency, as well as demineralization of bone are occurring in children and adolescents. A study at the Children's Hospital of Boston estimated that 12% of all infants and toddlers are Vitamin D deficient. The researchers posited that pregnant and breastfeeding women do not get enough Vitamin D, and inadvertently put their children at risk.
Since then, new information has surfaced which outs a whole new face on the issue of Vitamin D deficiency in pregnant and nursing women. Not only does it challenge the previous definition of Vitamin D deficiency, but it concurs with the move to attach a new and more exacting criteria to the diagnosis. Further, new evidence is suggesting that the physiologic manifestations of Vitamin D and calcium deficiency far transcend the musculo-skeletal system. Finally, based on so many new revelations, it is being debated that the requirement for Vitamin D supplementation should be increased.
In the past, Vitamin D deficiency has been defined as having less than the circulating concentration of 10 ng/mL of Vitamin D. Many practitioners and investigators now define it as less than 32 ng/mL. Further, historically, the deficiency parameter was determined cased solely upon statistical distributions. Recent data, however, has demonstrated that the cutoff should be based upon an entire constellation of biological markers that are diminished when Vitamin D is low.
We also believed that the most significant impact of Vitamin D deficiency in pregnancy was related to compromise of the fetal and infant skeleton. Despite its implications, most skeletal morbidity associated with Vitamin D deficiency can be corrected with adequate supplementation after delivery. Now, however, the import of Vitamin D is known to extend far beyond the skeleton. It is believed that Vitamin D somehow plays a role in fetal "imprinting", which may affect the individual's vulnerability to certain diseases in life. We believe that these diseases may be broad and include such illnesses as insulin-resistance, diabetes, multiple sclerosis, rheumatoid arthritis, cardiovascular disease, and even some cancers. Further, during pregnancy, the deficiency may increase risk for intra-uterine growth restriction, birth defects and pre-eclampsia.
Finally, it is now believed that Vitamin D may actually play a role in stimulating certain components of the immune system. It has even been suggested that Vitamin D may be helpful in containing tubercular infections.
Aside from broadening our understanding of the need for Vitamin D, this study suggests that MOST Americans have some degree of deficiency. It is postulated that here in North America, this is a direct result of an inadequate amount of sunlight. It is the sun's ultraviolet light which enables us to produce Vitamin D within our skin. Consequently, if our sun exposure is limited, Vitamin D will be sub-optimal.
Since adequate sunlight may not always be feasible, and due to the risk of skin cancer with prolonged sun exposure, the authors have recommended Vitamin D supplements. There is no general consensus as to an appropriate dose for all populations. All adults can safely take 2000 IU daily. The final recommendation was that pregnant women have their Vitamin D levels checked, particularly in the first trimester. Hopefully, this would identify those at risk and whom are most in need of supplementation.