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.
Recommended Daily Allowances. Adult men and women, including pregnant or nursing women, should consume 15 micrograms of vitamin D daily, according to the Institute of Medicine's Food and Nutrition Board. Vitamin D intake can also be measured in International Units; by this measure, adults require 600 International Units daily. Seniors over 70 years of age have a higher RDA -- 800 International Units, or 20 micrograms, of vitamin D each day.