Each vitamin has a scientific name. For example, vitamin A is known as retinol, vitamin B1 is known as thiamin, vitamin C is known as ascorbic acid, vitamin D is known as calciferol and vitamin E is known as alpha-tocopherol.
A daily dose of vitamins has recommended and upper tolerable limits for each of 24 nutrients established by the Institute of Medicine, according to WebMD. For example, adult males should take 3,000 international units per day of vitamin A, while women should take 2,310 IU per day.
The recommended amount of vitamin C in an adult's daily dietary intake is between 65 and 90 milligrams, explains Mayo Clinic. However, up to 2,000 milligrams can be ingested by an average adult and still be considered safe.
As of 2010, the Institute of Medicine recommends persons aged 9 years to 70 years consume between 600 international units and no more than 4,000 international units of vitamin D per day, says WebMD. The daily recommended dosage varies depending on a person's age, weight and sun exposure.
Common vitamins that people need to take include vitamin C, thiamine, pantothenic acid, riboflavin, B-12, folic acid and biotin, states WebMD. These are all water-soluble vitamins, and unlike fat-soluble vitamins, they need to be consumed regularly.
For adults, the recommended dietary allowance for vitamin A is 900 micrograms per day for males and 700 micrograms per day for females, says MedlinePlus. Doses vary between 300 to 600 micrograms per day for infants and children, reports WebMD.
As of 2010, the recommended daily allowance of vitamin D for adults ages 18 to 70 is 600 international units, according to Mayo Clinic. People can attain an ideal vitamin D blood content of 20 nanograms per milliliter through daily exposure to sunlight.
The best time to take vitamins is in the morning, according to Mother Nature Network. Upon waking from sleep, the body needs nutrients for energy to start the activities of the day. Vitamins supplements are synthetic substances that break down and are absorbed into the body best with food.
The recommended daily allowance for vitamin D is 400 international units for infants and 600 to 800 international units for older individuals. Good sources of vitamin D include fatty fish such as salmon and tuna, fish liver oils and fortified foods such as milk, notes the National Institutes of Heal
The daily dosage for vitamin C varies depending on age, gender and lifestyle choices such as smoking. The National Institutes of Health provide a list of the average daily recommended amount of vitamin C in milligrams, according to its website.