Taking multivitamins has become a daily habit for many people looking to support their energy, immunity, or overall wellbeing. But one common question remains: how long does it actually take before you start noticing the effects? The answer is not the same for everyone and depends on several factors, including the type of vitamin, how your body absorbs it, and your individual nutrient status.
Type of Vitamin: Water Soluble vs Fat Soluble
All vitamins can be classified as either water soluble or fat soluble, which refers to how they are stored in the body. The major fat-soluble vitamins are A, D, E and K, while vitamin C and B vitamins (including folate) are water-soluble.
Water-soluble supplements act faster because they are absorbed into the bloodstream more quickly. However, any surplus water-soluble vitamins are rapidly flushed out of the body (1).
How Are Vitamins Processed by the Body?
The way vitamins are processed varies depending on whether they are water or fat soluble.
- Fat-soluble vitamins (A, D, E, K) are usually found in animal fats, vegetable oils, dairy foods, liver, and oily fish. When consumed, they are absorbed in the intestine and either stored in fatty tissue throughout the body or kept in the liver until needed.
- Water-soluble vitamins (vitamin C and B vitamins) come from fruits, vegetables, grains, and dairy foods. These are absorbed into the bloodstream during digestion and transported directly to where they are needed (1).
Minerals are absorbed in similar ways depending on their properties.
Factors that Affect Vitamin Efficacy
- Current vitamin levels – If certain vitamins are low, you’re more likely to notice benefits sooner. The timeframe varies, but deficiencies often lead to faster and more noticeable changes.
- Diet – Low dietary fat can reduce absorption of fat-soluble vitamins (A, D, E, K). Pairing certain nutrients can improve bioavailability, for example vitamin C with iron or vitamin D with calcium (6).
- Age – As we age, the ability to absorb some nutrients declines. Research shows absorption of vitamin B12, vitamin D, and calcium is specifically reduced in older adults (7).
How Does the Body Use Vitamins?
When you take a vitamin, it begins its journey in the digestive tract.
- In the stomach, vitamins are broken down by stomach acids.
- In the small intestine, water-soluble vitamins are carried directly into the bloodstream, while fat-soluble vitamins are broken down further by bile acids before being stored in the liver or fatty tissue.
From there:
- Vitamin D strengthens bones.
- Vitamin B12 helps keep nerve and red blood cells healthy, supporting energy and brain function.
- Vitamin C and E act as antioxidants to prevent cell damage.
- Vitamin A supports vision and slows eye degeneration.
- Vitamin K activates proteins essential for blood clotting and bone health (2).
How Long Do Vitamins Take to Work?
- Water-soluble vitamins (B, C): These can begin to act within hours, though noticeable effects may take days or weeks. Deficiencies often result in faster improvements.
- Fat-soluble vitamins (A, D, E, K): These build up gradually in the body, so benefits typically appear after weeks or months.
In general:
- Water-soluble vitamins → noticeable effects in days.
- Fat-soluble vitamins → gradual improvements over weeks to months.
Some vitamins are taken only during specific life stages. For example, folate is recommended for women three months before conception and during the first 12 weeks of pregnancy (1,3).
How Can You Tell When Vitamins Are Working?
The most reliable sign is a return to normal functioning. For example, fatigue from a deficiency may ease after a few days or weeks of supplementation.
According to Suzanne Soliman, Pharm.D., BCMAS, obvious improvements may include:
- Better sleep and mood
- Increased energy
- Reduced digestive discomfort
- Enhanced physical activity
Subtle changes may take longer to appear, such as shifts in blood markers, improvements in appetite, or reduced reliance on medications.
Keep in mind that the placebo effect can play a role. A trial period of consistent multivitamin supplementation, diet, and lifestyle is needed to truly gauge results (5).
Frequently Asked Questions (FAQs)
Will I feel different after taking multivitamins?
Not always right away. If you’re deficient, you may notice more energy, improved mood, or sharper focus within a few weeks.
What affects how quickly multivitamins work?
Your nutrient levels, diet, absorption capacity, type of vitamin, and how consistently you take them.
Should I take multivitamins with food?
Yes. Fat-soluble vitamins (A, D, E, K) absorb better with meals containing fat. Some multivitamins may upset your stomach on an empty stomach.
How will I know if the multivitamin is working?
Energy, focus, mood, sleep quality, hair and nail strength, and overall vitality are common signs—but sometimes changes are internal and can only be confirmed through testing.
References
- https://kinfertility.com.au/blog/how-long-do-vitamins-take-to-work#how-does-your-body-use-vitamins
- https://www.pennmedicine.org/news
- https://www.nbcnews.com/better/health/7-food-pairings-will-increase-nutrient-absorption-ncna889181
- https://www.eatingwell.com/how-to-tell-if-supplements-are-working-11741981
- https://www.ncbi.nlm.nih.gov/books/NBK513296
- https://www.naturemade.com/blogs/health-articles/how-long-does-it-take-for-vitamins-to-work
- https://www.nature.com/articles/boneres201641
