Daily vitamin requirements are also known as the RDA's, which is a short form, which stands for "Recommended Daily Allowance." The daily vitamin requirements are determined by the National Academy's Food and Nutrition Board.
It's worth admitting, however, that you will come across contradictory opinions about the daily vitamin requirements (as well as about kids daily vitamin requirements). Many health experts claim that taking in the RDA's only puts off signs of vitamin and mineral deficiencies, and does not promote the best health. These people, for that reason, stress the importance of taking in more (and sometimes considerably more) than the recommended daily requirements.
Others, nonetheless, claim that we get vitamins from our foods anyway, so there is no need to take in any supplements. Furthermore, some of health experts who are consistent with this opinion point to research that show that taking mega doses of vitamin supplements can even be dangerous to human's health.
So let's try to shed some light on the issue.
First of all, it is true that taking much more than the daily vitamin requirements could be harmful. Particularly the fat-soluble vitamins like Vitamin A and E can cause toxicity and other side effects, as they are stored in the fat tissues and cannot be readily excreted by the body.
Even the water-soluble vitamins, for example Vitamin C, have been observed to have bad side effects if taken in large amounts, such as the development of kidney stones.
On the other hand, we all know that vitamins are essential to the best health, so we certainly need them. And it is an acknowledged fact that most people do not even get the RDA's from natural food sources. Let's take a look at some reasons for this.
The first reason why a lot of people, particularly in the Western World, do not take in the daily vitamin requirements is due to the fact that the soil now used to grow crops considerably differs from that a few generations ago.
Because of modern farming approaches, the soil has been for the most part depleted of minerals and vitamins essential to our health. Thus, unless you continually eat organic produce (most people don't) you might be not receiving the adults daily vitamin requirements (as well as mineral requirements).
For instance, consider this: an analysis of a wide array of staple foods in Canada counting potatoes, onion, bananas, tomatoes, broccoli, apples, etc, was commissioned by CTV news and The Globe and Mail.
Let's bring into play potatoes as an example. The analysis found that over the last fifty years the potatoes have lost: 100% of Vitamin A, 57% of iron and Vitamin C, 28% of Calcium, 50% of riboflavin, 18% of thiamine.
Of the seven elements analyzed only levels of niacin had increased. The outcome was similar for all the twenty five vegetables and fruits tested. Utterly bad results were observed from broccoli in which every nutrient had declined noticeably including Calcium with niacin down 63%.
A professor at Food Policy centre in England, Tim Lang, says as an additional example of how the food has been despoiled is that one would have to eat seven oranges today to get the matching level of Vitamin A than people who lived fifty years ago received from eating only one orange.