Do Supplements Break a Fast?
Last updated: August 2026 · Reviewed by the FactoWiki Editorial Team for clarity and source accuracy
It depends on the fast and the supplement. Calorie-free vitamins and minerals do not meaningfully break any fast. Anything with protein, carbohydrate, fat or sugar does — including collagen, BCAAs, gummies and softgel oils. For fat-soluble vitamins there is a separate problem: without fat, you absorb far less.
Key takeaways
- Calorie-free vitamins and minerals: fine. Protein, carbs, fat or sugar: not fine.
- Collagen and BCAAs contain protein and calories — they break a fast.
- Fat-soluble vitamins absorb poorly without food, so fasting undermines them anyway.
What does not break a fast
Vitamin C, B vitamins, most minerals in capsule form, creatine monohydrate powder, electrolytes without added sugar, and black coffee or plain tea. These supply negligible or zero calories and do not trigger a meaningful insulin response. If your fast is for autophagy or metabolic reasons, these are fine.
What does
Collagen peptides (protein, roughly 40 kcal per 10 g), BCAAs and EAAs (amino acids trigger mTOR, which is the specific thing autophagy fasting aims to avoid), gummy vitamins (sugar), softgels and fish oil (fat), and anything in a flavoured drink with sweeteners that may provoke a cephalic insulin response in some people.
The absorption problem nobody mentions
Vitamins A, D, E and K are fat-soluble and need dietary fat to absorb properly. Taking your vitamin D during a fasted window means absorbing a fraction of it. Even if it does not break the fast, it wastes the dose. Move fat-soluble vitamins to your eating window regardless of the fasting question.
Key ingredients to understand
The ingredients most relevant to this question, with what the evidence actually supports:
- Vitamin D3 (Cholecalciferol) — Vitamin D3 is the form your skin makes from sunlight and the form that raises and maintains blood levels most effectively. Deficiency is…
- Electrolytes — Electrolytes are the charged minerals that regulate fluid balance, nerve signalling and muscle contraction — principally sodium, potassium,…
- Collagen Peptides — Hydrolysed collagen peptides have some of the better evidence in the supplement market for skin hydration and elasticity, and moderate evidence…
- Creatine Monohydrate — Creatine monohydrate is the most researched sports supplement in existence, with hundreds of trials supporting increased strength and lean mass…
Frequently asked questions
What about electrolytes?
Plain sodium, potassium and magnesium without sugar do not break a fast, and they are often helpful during longer fasts.
Do gummy vitamins break a fast?
Yes. They are mostly sugar or sugar alcohols, and they contain calories.
What should I move to my eating window?
Vitamins A, D, E and K, fish oil, CoQ10, and anything with protein or calories. Water-soluble vitamins and minerals can stay in the fasted window.
Related on FactoWiki
- All health answers
- Ingredient evidence guides
- Vitamin D3 (Cholecalciferol) — ingredient guide
- Electrolytes — ingredient guide
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