For intermittent fasting and time-restricted eating
When should you take supplements if you do intermittent fasting?
When should you take supplements if you do intermittent fasting?
If you skip breakfast, fat-soluble vitamins like D3, K2 and E and omega-3 absorb best with the first meal inside your eating window, not on an empty stomach. Water-soluble vitamins such as vitamin C and most others can be taken any time. Minerals still need spacing from each other, regardless of when your window opens.
Fasted vs with-food, what changes
Skipping breakfast moves the first meal of the day, not the principle. Fat-soluble vitamins need fat to absorb, so they move with the meal. Calming evening supplements stay in the evening regardless of when you eat.
What you can take while fasting
Water-soluble vitamins (B-complex, vitamin C), most adaptogens, and electrolytes are fine on an empty stomach and will not break a fast in a meaningful way. Black coffee or plain water is the usual carrier.
What to save for your eating window
Fat-soluble vitamins (A, D, E, K), omega-3, CoQ10, and most multivitamins go with the first real meal of your window, ideally one that contains some fat.
A 16:8 example
Wake at 7 am, eating window 12 to 8 pm. On waking: water and electrolytes if you use them. 12 pm, first meal: fat-soluble vitamins, omega-3, multivitamin. 7 pm, last meal: any remaining items that do better with food. Before bed, outside the window: magnesium glycinate is fine.
Frequently asked
Does a fish oil capsule break a fast?
Technically yes, it contains calories. In practice many people take it with their first meal anyway, since it absorbs better with food.
Can I take a multivitamin with black coffee on an empty stomach?
Water-soluble parts will absorb, fat-soluble parts will not. Save it for the first meal of your window so the whole capsule earns its keep.
What about taking iron while fasting?
Iron actually absorbs better on an empty stomach, but it can cause nausea. If you tolerate it, fasted is fine, away from coffee or tea.
Keep exploring
This guide does not address whether you should fast or not. For health goals or medical conditions, speak to a clinician.
Sources
See our full sources list for the references behind our guidance.