If you have the blood test for B12, that is required by a doctor.
You can take both, without testing, but it would be best to know if you have a problem with B12.
The genetic errors of methylation can only be determined by the DNA testing. This error also affects the methylation of B12, so you will want to use a methylcobalamin instead of cyanocobalamin if in doubt.
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All truths are easy to understand once they are discovered; the point is to discover them.-- Galileo Galilei
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Weezie looking at petunias 8.25.2017
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