If you’re interested in having your vitamin C levels tested, it’s time to rope in a health care professional. “Discuss with your doctor your concerns and let them advise you if they think a blood test for ascorbic acid is indicated,” suggests Keri Gans, RDN, dietitian and author of The Small Change Diet.
Just know that you might get a little pushback or hesitation from your practitioner. “Vitamin C testing is rare and usually very badly done,” Michels explains. In a more reactive stance (instead of a proactive nutritional assessment approach), “at the moment, doctors only test for vitamin C when they suspect you might have a deficiency,” he shares.
But as holistic nutritionist Ella Davar, R.D., CDN, expounds, there is a simple blood test (aka serum ascorbic acid) to analyze your levels of vitamin C. The process is straightforward and similar to other blood tests: You have your blood drawn and it’s sent to a lab for analysis.
Indeed, “there is a vitamin C blood test available from all major testing facilities,” Michels explains. But, he adds, it’s quite equipped to determine if you have a vitamin C deficiency—and less helpful to sensitively capture insufficiency.
Davar says that her favorite (and more specialized) blood test that can check your vitamin C levels is SpectraCell’s Micronutrient Test Panel. This panel measures your levels of 31 vitamins (including vitamin C), minerals, amino and fatty acids, antioxidants, and metabolites, along with how they affect your cellular function, she explains. “This test also measures levels of glutathione and vitamin C, which I use to personalize diet recommendations for my clients,” Davar says.
If you get a vitamin C blood test, Michels recommends making sure that you haven’t had any vitamin C supplements for at least one day beforehand to get an accurate idea of your vitamin C status. “You should limit your intake of fruits or vegetables the night before the test—and it should be taken fasting,” he says.