The Recomended Daily Allowance for Vitamin D has been to low

What is Vitamin D ?

Explanation of the Pandemic of Vitamin D Deficiency

Only 20% of our vitamin D reserve is meant to come from the diet. The remaining 80% is expected to be produced in our skin from the UV-B of the sun. In contrast to the context of the recommendations of the 1960s of 4000 to 5000 IU/d to avoid rickets, our diet today is poor in wild fish (×10 richer in vitamin D), wild eggs, and fresh milk. Children are playing and people are working indoors all day long, and powerful sunprotective cosmetics are used to prevent melanoma. Even sunny countries such as Greece present a high prevalence of vitamin D deficiency, as the angle of the sun rays from autumn to spring do not result in sufficient vitamin D production with usual sun exposure.

Optimal Vitamin D Supplementation

With the target for vitamin D set at 100 nmol/L, the dose, frequency, and duration of supplementation will be important factors for healthy subjects committed to optimizing their nutritional status. 

Since in the case of vitamin D, serum levels depend on dietary intake (20%) and sun exposure (80%), a practical approach would be to recommend at least the three-fourths of the upper tolerable dose proposed by the Endocrine Society to be taken as a supplement all year long except for circumstances such as vacations in which one engages in sunbathing. This could translate to, for instance, 1000 IU for children <1 year on enriched formula and 1500 IU for those older than 6 months who are breastfed, 3000 IU for children >1 year of age, and up to 8000 IU for young adults and thereafter, with non-pediatric doses adapted to the body mass index with the target set to 100 nmol/L instead of 50 nmol/L. More importantly, according to the Endocrine Society’s clinical practice guidelines, doses up to 1000 IU/d for infants up to 6 months, 1500 IU/d for infants from 6 months to 1 year, 2500 IU/d for children aged 1-3 years, 3000 IU/d for children aged 4-8 years, and 4000 IU/d for everyone over 8 years can be given safely without medical supervision just to prevent vitamin D deficiency, while higher doses may be needed to correct hypovitaminosis D.

Importance of Vitamin D Supplementation

Such a strategy relies on adequate supplementation among pregnant and lactating women, and on timely supplementation of every newborn before seroconversion towards autoimmune targets occurs. The benefits for individuals’ general health status, apart from the obvious gains in skeletal health, cannot be fully foreseen, but may very well be surprisingly greater than expected given the impact of vitamin D deficiency on metabolic syndrome itself. Improvements in vitamin D status may help reduce the public health burden of metabolic syndrome and of potential subsequent health conditions, including type 2 diabetes and cardiovascular disease.

Other considerations

Reasons for a 5000 IU Prescription

• Diagnosed Deficiency: 

  A blood test showed your levels were low (below 20-30 ng/mL), requiring a higher dose to restore normal levels. 
• Inadequate Sunlight: 

  Living in northern climates or spending most time indoors reduces natural Vitamin D production. 
• Malabsorption Issues: 

  Digestive disorders (Celiac, Crohn's) or obesity can hinder Vitamin D absorption from food, necessitating higher intake. 
• Bone Health: 

  Essential for calcium absorption, supporting strong bones and teeth. 
• Immune Support: 

  Vitamin D plays a role in immune function, and deficiency can lead to getting sick more often. 
• Specific Health Conditions: 

  May be used for conditions like osteoporosis, certain cancers, or to support heart/metabolic health. 

Why is Vitamin D Important?

CONCLUSION

Unfortunately, medicine took a very long time to realize that vitamin D is not simply a vitamin that prevents rickets. For that purpose, 400-600 IU/d may be enough. However, we know today that vitamin D is a powerful nuclear receptor-activating hormone of critical importance, especially to the immune system. With the available data mentioned above, the proposed doses would probably suffice to maintain vitamin D levels around or over 75-100 nmol/L, with practically zero risk of toxicity. Undeniably, further studies are needed to clarify the optimal supplementation of vitamin D, although it is uncertain whether a universal recommended dietary allowance is feasible. Meanwhile, actions are urgently needed to protect the global population from the threats posed by vitamin D deficiency.

Vitamin D RDAs—A Promising Public Health Goal for MAHA