Think about it, 20833 % of pretty much any supplement is not good for you. You will be peeing highlighter yellow as you kidneys struggle to filter the other 20733% your body doesn't need. Extremely high does of vitamin B12 are associated with increased risk of cancer, this is straight from both studies done in the US and EU - google them as I can't site them here on Amazon. A Headache soon after you take it is a sure sign your body is struggling to deal with massive excess. Why do manufactures make such big does? Because is dirt cheap to produce and 100% RDA doesn't market well when the competition offers more. Note that methyl B12 in this and other supplements does not come from the fruits & vegies listed in the ingredients. It is manufactured through fermentation in a lab. The fruits and vegies are added for marketing and taste. It gives an illusion to the consumer that the vitamin was derived from some magical juicing process of 10 tons of fresh produce. So how do you best take this or other B12? Pour the liquid into a dropper bottle instead of spray. Use about half a drop a day or less. You'll still get a few hundred times more than the 2.6 mcg recommended daily allowance. But you will get BETTER health benefits without the risk and side effects