This gets to the heart of the numerous multi-vitamin flaws. How quickly and to what extent do changes happen due to the consumption of faulty vitamin forms, incorrect dosages, and the absence of necessary synergistic nutrients. Luckily, most are slow to initiate an observable response. But that does not mean that inside conditions are beginning to turn unfavorable for body processes.
WHOLE BODY APPROACH
It is vital to also know that the body has to be viewed as a whole and studying just one nutrient could miss a behind the scene team of related pathway involved nutrients. An analogy would be like a row of dominos. When one falls, they all continue to fall, until one is out of place and stops the cascade. A vitamin that is deficient or even one that is at an excess is like the domino that is out of line and interrupts the sequence.
Fortunately, the body has many protective and adaptive processes to overcome and correct small threats to functions, often for quite some time. But, at some point, too much damage develops and an observable disease state erupts.
A MOST DIFFICULT ANALYSIS
Humans vary quite a lot in a number of factors such as diets, lifestyles, activity, organ functions, digestion, absorption, elimination, genetics, and metabolism rates. These factors make it difficult for Scientists to construct studies to compare test groups for the influence of vitamins on health and disease. Any attempt to put resulting percentages in place are most likely just guesstimates. They may work for some groups and not others.
But, using the science that is available, generalities will have to do to let the Public know possible consequences of certain vitamin forms, dosages, and synergistic combinations. An attempt will also be make eventually to categorize consequences as to seriousness, length of time to develop, and conditions needing other companion nutrient(s).
FOLATE VERSUS FOLIC ACID (for details see pages)
Bottomline: Find multi-vitamins with a natural form of folate as L-methylfolate or 5-MTHF. Limit dosages in supplements to 200 mcg. Consume foods with natural folates; fruits, vegetables, nuts, beans, etc. If have a history of cancer, do not consume any folic acid and eat un-enriched cereals and grains. If taking some supplemental folates, also take a little vitamin B12, as 5-10 mcg, not 1000.