Does Vitamin B12 Break a Fast?

If you’re supplementing with vitamin B12, should you wait to take it during your eating window? Today, I’m diving into whether or not vitamin B12 breaks a fast.

Does Vitamin B12 Break a Fast?

Whether or not something breaks a fast depends on your goal with Intermittent Fasting. If you’re looking for the gut health perks of Intermittent Fasting, then anything other than water and electrolytes will likely break a fast. However, if you’re looking to achieve a weight loss goal, anything that causes insulin (the storing hormone) to spike will break a fast.

Assuming that we’re talking about pure vitamin B12 (meaning, not in gummy form), then this won’t break a fast if your goal is weight loss. Because vitamin B12 doesn’t contain any protein or carbs that could spike insulin, the body stays in a fat burning state during the fast. However, if you take vitamin B12 in a gummy form or if your supplement contains any sugar or protein (always check the label!), then this will break a fast.

Related: Does Fish Oil Break a Fast?

If your goal is primarily gut health, then you might want to stick with the sublingual vitamin B12 supplements to be on the safe side. Technically any food or drink (other than water) can stop the gut cleaning process called the Migrating Motor Complex (MMC) and end the gut health perks of the fast (even though you could still be getting the fat burning perks). However, sublingual vitamin B12 is absorbed directly through the tissue under your tongue. This means it bypasses the GI tract and theoretically doesn’t stop the MMC (although there aren’t any specific studies on this).

So if you need to take vitamin B12 during the fast and you want to optimize for both gut health and weight loss perks, you might want to check out a sublingual zero sugar brand.