We have some reservations about doing blood tests to track vitamin and mineral deficiencies.
Often, blood tests are normal but one can still be deficient in various substances. Some vitamin and mineral levels cannot be accurately assessed or are measured in the wrong way (for example, magnesium levels are measured in the blood, but most magnesium resides in the cells, so one can have “normal” magnesium blood levels but still have deficiencies in the tissues).
Also, many people (up to 70%) who end up in the hospital with a heart attack have normal LDL or HDL cholesterol levels, demonstrating that many other mechanisms contribute to heart disease risk (which are not measured in a blood panel). The same applies for many other blood biomarkers and diseases.
Additionally, the cut-off values that labs use to determine deficiencies are not the ideal cut-offs values: they are often based on population averages. In other words, if many people are deficient in a specific biomarker, often such levels will be considered “normal”.
Furthermore, the cut-off values are often based on crude disease outcomes: if they are below or above a specific cut-off value, you can become (very) ill. But these cut-offs are often not based on optimal values for a long, healthy life. For example, vitamin D levels are often considered as abnormal if they are less than 20 ng/ml (a “deficiency”), but we see that optimal vitamin D levels could be up to 90 ng/mL, and even higher). Also, the cut-off values are not based on exact science, but more educated guesses.
For DNA testing, this is even worse. For example, a DNA test looks at one tiny part of a gene that has been associated with in increased risk of vitamin B deficiency, but there could be many other variations in the same gene, or in other genes, that perhaps reduce your risk of vitamin B deficiency but that are not looked at, or are not even known (yet).
It’s almost impossible to really test accurately for vitamin and mineral deficiencies (you cannot even test for all vitamins and minerals to begin with). The best way to address this issue is just to supplement with vitamins and minerals so you are sure you have enough of them.
We explain more about blood testing here: