The best time of day to take vitamins is first thing in the morning. According to the New Health Guide, taking vitamins first thing in the morning ensures best absorption.
New Health Guide explains that vitamins are best taken within 30 minutes of the time that a person eats breakfast. The food facilitates the breakdown of the vitamins. Taking vitamins in the morning allows the body to use them optimally throughout the day.
There are particular vitamin combinations that should not be taken together, New Health Guide notes. To facilitate absorption, calcium must be taken separately from iron. Vitamin B12 and folic acid are best taken simultaneously. Taking folic acid by itself can mask anemia caused by a vitamin B12 deficiency.