Vitamin pills are, at best, a supplement. They are designed to provide a dietary catch-up for the vitamins we miss in our daily diet. Given that the average American's diet isn’t the healthiest, particularly with processed foods, vitamin pills can help plug the gaps. However, vitamins have different levels of benefit depending on when they are taken. Timing those benefits is the most efficient use of the supplement.
You cannot rely on vitamin pills alone. Although they include many critical elements necessary for body health, they do nothing on their own inside the body. It is through digestion with other real foods that vitamin pills provide their added benefit. So taking a vitamin pill before going to sleep negates its potential value, while taking it before a meal optimizes its potential benefits.
People's Bodies are Different
Your metabolic rate is also a factor. Some people will get more from vitamin pills than others simply because their digestion of food is more efficient. For instance, a marathon runner’s body will easily sap the full benefit of a vitamin supplement, while a senior citizen’s system may benefit only partially. There is no standard consumption metric that applies to everyone.
The morning breakfast is probably the best time to consume vitamins, and multivitamins in particular. Your body then has its initial meal and unlimited time to digest the vitamin pill while being active. A nutritious meal provides natural vitamins and minerals with which the supplement can mix.
If your breakfast is just coffee and a snack before hitting the road, then the next best alternative is the midday meal, since it will have have plenty of digestive time and physical activity following it.
Multivitamins Vs. Single Vitamins
The value of individual vitamins is dependent on how you are combining them. Vitamins B and C work well with the breakfast foods. However, calcium and iron and other minerals that work against each other are best taken at different times of the day. Trying to time all of these issues could get difficult. That one of the reasons why a multivitamin with the first hearty meal of the day is a good choice.
The Professional Fitness Exception
For athletes and fitness types, the targeting of vitamins becomes integral to the benefits of workouts and performance. So in these cases the consumption of vitamins or supplements right before or right after the activity can result in performance enhancement. However, these activities are on the extreme end of physical training and the average person would not see the same results instantaneously without going through the same fitness and diet regimen.