//Vitamin D, Science

Vitamin D, Science

Scientific Advisory Committee on Nutrition (SACN)


SACN vitamin D and health report


A reference nutrient intake (RNI) of 10 micrograms (400 units) of vitamin D per day, throughout the year, for everyone in the general population aged 4 years and older

The RNI and safe intakes were developed to ensure that the majority of the UK population has enough vitamin D to protect musculoskeletal health, all year round.

SACN did not take account of sunlight exposure in making recommendations because of the number and complexity of factors that affect skin synthesis of vitamin D.

Vitamin D

Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline (2011)

The Endocrine Society


Journal of Clinical Endocrinology


Vitamin D deficiency is very common in all age groups

Few foods contain vitamin D

Task Force recommended supplementation, depending on age and clinical circumstances

Measurement of serum 25-hydroxyvitamin D level, in patients at risk for deficiency

Treatment with supplement recommended for deficient patients


About 42% of the US population is vitamin D deficient

82% in black people

70% in Hispanics

Nutrients, 15 July 2020


Immunologic Effects of Vitamin D on Human Health and Disease

Calcium and phosphate metabolism, bones

1,25-dihydroxyvitamin D, active form of vitamin D

Immunomodulatory hormone

Innate and adaptive immune systems

Vitamin D receptor and enzymes in;

T lymphocytes
B lymphocytes
Dendritic cells

Vascular endothelial membrane stability

Association with low blood levels of 25-hydroxyvitamin D

Several immune-related diseases and disorders


Type 1 diabetes

Multiple sclerosis

Rheumatoid arthritis



Respiratory infection


Optimal Serum 25-hydroxyvitamin D

It is advisable to increase vitamin D intake and have sensible sunlight exposure

Maintain serum 25-hydroxyvitamin D at least,

30 ng/mL (75 nmol/L)

and preferably

40–60 ng/mL (100–150 nmol/L)

Recommended dosage for vitamin D intake in individuals who are at risk for vitamin D
Deficiency (1,000 iu = 25 mcg)

Age, years Daily requirement Upper limit
Years Requirement

0 – 1 400 – 1,000 2,000
1 – 18 600 – 1,000 4,000
18 + 1500- 2000 10,000
Obese 4,000 – 6000 10,000

For deficiency 0 – 1 year

2000 IU/day or 50,000 IU/week

of vitamin D2 or D3 for at least 6 weeks

to achieve serum 25(OH)D more than 30 ng/mL (75 nmol/L)

maintenance therapy of 400–1000 IU/d

For deficiency 1 – 18 years

2000 IU/day or 50,000 IU/week of vitamin D2 or D3 for at least 6 weeks

to achieve serum 25(OH)D more than 30 ng/mL (75 nmol/L)

maintenance therapy of 600–1000 IU/d

For deficiency after 18 years

6000 IU/day or 50,000 IU/week

of vitamin D2 or D3 for 8 weeks

to achieve serum 25(OH)D more than 30 ng/mL (75 nmol/L)

maintenance therapy of 1500 –2000 IU/d

Obese and malabsorptive patients

Dosage should be increased by 2–3 times

Respiratory Viral Infection and COVID-19

Outbreak of influenza infection is periodic and usually occurs during the wintertime at higher latitudes

but is sporadic throughout the year in the tropical area

Association between low level of serum 25(OH)D and
incidence and severity of respiratory tract infection in children and adults

A recent meta-analysis of 25 RCTs showed that supplementation of vitamin D2 or D3 can protect against the development of acute respiratory tract infection compared with placebo



Rate of symptomatic infection, morbidity and mortality observed

African American


Worldwide on average approximately 40% of children and adults have circulating levels of 25(OH)D less than 20 ng/mL (50 nmol/L)

It is therefore reasonable to institute as a standard of care to give at least one single dose of 50,000 of vitamin D to all COVID-19 patients as soon as possible after being hospitalized

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