How to measure your antioxidant levels: 5 methods compared

Short answer

The most practical way to check your antioxidant status is to measure carotenoids, the antioxidant pigments from fruit and vegetables. You can do that with a lab blood test, or non invasively with a skin scanner such as Nu Skin's Prysm iO, which reads the fingertip in about 15 seconds.

Why carotenoids are the marker

There is no single test for every antioxidant in the body. Carotenoids are the best studied marker because they come only from diet, they act as antioxidants, and they can be measured accurately in both blood and skin. Higher levels mean a diet richer in colourful plants.

Comparison of five methods: blood test, Raman scanner, reflection spectroscopy, Prysm iO, food diary, by convenience and objectivity — Five ways to estimate carotenoid antioxidant status.

The five methods

Method	How it works	Time	Best for
Blood test (plasma carotenoids)	Blood draw analysed in a lab, usually by HPLC	Days	Clinical research reference
Resonance Raman scanner	Blue laser light on the palm (e.g. Pharmanex BioPhotonic Scanner)	Seconds	Earlier generation scanning
Reflection spectroscopy	White light and finger pressure (e.g. Veggie Meter)	Short scan	Nutrition research
Prysm iO	Hyperspectral absorption plus AI at the fingertip	About 15 s	Clinics and personal tracking
Food diary or questionnaire	You record what you eat	Days	Habits, not levels

How the methods compare

Blood tests are the reference, but they are invasive, slower and move with your last few meals and the season.

Skin scanners reflect intake over recent weeks, need no needle, and are fast enough to repeat often. Raman measurements correlate with plasma carotenoids at about r = 0.62 and with skin biopsy carotenoids at about r = 0.66 in published work. Reflection spectroscopy devices have shown correlations around r = 0.81 with plasma. Nu Skin reports a strong correlation between Prysm iO and blood carotenoids.

Food diaries are useful for habits, but people misremember. In one study, self reported fruit and vegetable intake was not significantly linked to measured carotenoids.

How to start

Get a baseline scan.
Change one thing: more colourful vegetables, a carotenoid supplement, or quitting smoking.
Rescan after 4 to 8 weeks and compare.

Common questions

Is there a home test for antioxidant levels?

Yes. Fingertip skin carotenoid scanners such as Prysm iO give a reading in about 15 seconds without blood. They measure carotenoid antioxidants, which are the most studied marker of antioxidant intake from food.

Is a blood test more accurate than a skin scan?

Blood plasma carotenoids measured in a lab are the reference standard, but they swing with recent meals and the season. Skin carotenoids change more slowly, so they reflect your intake over recent weeks. That makes skin scanning practical for tracking a trend.

What is the best marker of fruit and vegetable intake?

Carotenoids in the blood or skin are the most widely used objective markers. Food questionnaires are much weaker. In research, self reported intake often correlates poorly with measured carotenoids.