“Taking ascorbic acid (vitamin C) supplements while wearing the sensor may falsely raise sensor glucose reading. Taking more than 500 mg of ascorbic acid per day may affect the sensor readings which could cause you to miss a severe low glucose event.”
Abbott, Freestyle Libre
What does 500 mg a day look like?
4 glasses of orange juice
2.5 cups of red bell pepper
6 cups of strawberries
3.5 cups of broccoli
Unless you’re chasing lows all day with OJ, or pounding strawberry smoothies, it’s pretty hard to hit 500mg of vitamin C a day via whole foods.
What you do need to watch out for is supplements.
Supplements that contain over 500mg include:
Airborne® (1,000 mg)
Emergen-C® (1,000 mg)
and many other Vitamin C supplements
Can I Still Use My CGM When Taking Vitamin C Supplements?
Yes! However, I wouldn’t bolus off the CGM results since they would be inaccurate. I would stick to finger sticks for the day(s) that you’re taking heavy dose supplements of Vitamin C.
Personally, I haven’t seen that the effects last past a few hours of taking high dose vitamin C, and the readings for me were never too far off, but you should definitely try it out yourself.