Most shark attacks occur less than 100 feet from the shore. More people are killed by bee stings and lightning than by shark attacks. Worldwide about 30 people die each year from shark attacks, which means a person has a one in 300 million chance of being killed by a shark. A shark attack most often occurs when a shark mistakes a person for a seal or other animal.
The new 2010 recommended daily allowance (RDA) is 600 IU for those 1-70 years of age and pregnant or breastfeeding women, and 800 IU for those over 71 years of age. An adequate blood level of vitamin D is 20 nanograms per milliliter, which can be achieved through daily skin exposure to sunlight.
How much vitamin D should adults take? According to the National Institutes of Health (NIH), the daily Adequate Intake (AI) for adults is 5 mcg (200 IU) daily for males, female, and pregnant/lactating women under the age of 50. People 50 to 70 years old should get 10 mcg daily (400 IU) daily, and those over 70 should get 15 mcg daily (600 IU). Based on recent research, Dr. Weil recommends 2,000 IU of vitamin D per day. Look for supplements that provide D3 (cholecalciferol) rather than D2 (ergocalciferol).