There are clearly some cases in which you need a blood test if your doctor suspects a nutrient deficiency—say, with potassium, magnesium, iron, or vitamin B12— especially when a drug increases the risk of one. (For example, the cancer drug Zytiga reduces blood potassium in many patients.) Iron blood testing for anemia is a gold standard for women with fatigue from excessive blood loss from menstruation, and B12 and magnesium testing may be warranted if you’re on acid reflux medication long term.
Nutritional deficiency testing should always be handled on a case-by-case basis. Most people do not need a massive nutritional panel that looks at amino acids, vitamins, and minerals, where inevitably something shows up low and you’re told you need a supplement to correct it. If your panel does reveal some deficiencies, always ask if correcting them (taking more of whatever nutrient is low) will produce a tangible, beneficial result.
Let me explain:
Hundreds of millions of dollars have been spent on studies looking at how high doses of vitamins B6 and B12 and folic acid affect a compound in the blood called homocysteine, which experts believe is a marker for cardiovascular disease in most individuals. The Bs did, in fact, lower blood homocysteine levels, and supplement companies jumped on that. But after several decades, experts are realizing that lowering homocysteine doesn’t really have much impact on heart health for most people. In other words, just because a blood test improves does not mean you will improve—with the exception of the obvious ones, such as cholesterol and glucose.
Again, some individual tests are worthwhile, but the majority are absolute nonsense. Be leery about extensive blood panel tests for the following:
Amino acids
Antioxidants
B-complex vitamins
Fatty acids
Metabolites
Minerals
Vitamins
I often hear from people who have been dealing with celiac disease or Crohn’s disease for years, both of which can impact nutrient absorption, or from those who’ve been on long-term extreme diets and are curious about possible nutrient deficiencies. If you’re in a similar situation, please read the Bariatric Surgery section, which lists a comprehensive panel of proven nutrient deficiency tests that can help you determine your own nutritional issues.
Researchers are starting to better understand that high doses of drugs (such as cholesterol-, acid-, and glucose-lowering medications) can lead to deficiencies because of the way they impact the production and absorption of some nutrients. Yet in medical school, students are still being taught about deficiencies that result from not getting enough nutrients in our diets (like scurvy from vitamin C deficiency) despite the fact that today’s nutritional shortcomings are often due to excess medications and extreme diets.
The Supplement Handbook - Mark Moyad
