Facts about Vitamin D
- 11
Kidney cells convert 25-hydroxyvitamin D into its active form, calcitriol, which regulates calcium absorption in the intestines and maintains blood phosphate levels.
- 10
Across multiple randomized controlled trials, vitamin D supplementation reduced respiratory tract infection rates by approximately 10 to 25 percent among participants with baseline deficiency.
- 09
Parathyroid glands regulate calcium levels by increasing vitamin D activation in the kidneys when blood calcium drops below 8.5 milligrams per deciliter.
- 08
Rickets cases in children increased dramatically during the Industrial Revolution when urban populations spent less time outdoors, leading researchers to identify vitamin D deficiency as the cause in the early 1900s.
- 07
Sunscreen with SPF 30 blocks approximately 97% of UVB radiation, reducing vitamin D synthesis in skin by up to 99% compared to unprotected exposure.
- 06
Fatty fish like salmon and mackerel contain 570 to 1,300 international units of vitamin D per 100-gram serving, making them among the richest natural food sources available.
- 05
Vitamin D deficiency affects approximately one billion people worldwide, with prevalence rates highest in Northern Europe and East Asia due to limited sunlight exposure.
- 04
Elderly individuals over 65 years old require 800 international units of vitamin D daily, double the recommendation for adults aged 19 to 50 years.
- 03
Fortified milk in North America typically contains 100 international units of vitamin D per 240-milliliter cup, established as a standard in the 1930s to combat rickets.
- 02
A 2010 study found that individuals with vitamin D deficiency had a 40% higher risk of depression compared to those with sufficient levels.
- 01
The human skin produces approximately 10,000 to 20,000 international units of vitamin D within 10 to 30 minutes of midday sun exposure.