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Should I take vitamins while water fasting?

The short answer:

Taking vitamins during water fasting is a controversial question. One point of view assumes that vitamins are Ok during fasting, while another view assumes that vitamins should be avoided during water fasting. In this article, you can find more about whether vitamins are ok or should be avoided while water fasting.

Key facts:

  • Water fasting means you are allowed to drink water only without any food.
  • If you plan to fast for more than 3 days, you have to ask your healthcare provider about the guidelines.
  • There is an assumption that vitamins are OK during water fasting and vitamin administration doesn’t break your fast. In this case, you should avoid those with high calories.
  • In contrast, there is a general assumption that vitamins should be avoided during fasting to allow your body to consume the stored fats and carbohydrates which is the main point of fasting.
  • Studies showed that water fasting doesn’t cause vitamin deficiency.
  • If you need to drink coffee, you should drink it black and avoid any calories while fasting.
  • It is better to take vitamin supplements with the first meal after fasting, a higher rate of absorption is expected under this condition.


What does water fasting mean?

Is it OK to take vitamins during fasting?

Does water fast cause vitamin deficiency?

Tips to take vitamin supplements during water fasting


What does water fasting mean?

Water fasting means you stop eating any food and you are only allowed to drink water. People commonly undergo water fasting to lose weight. Moreover, It is sometimes due to religious and spiritual causes.

Therapeutic water fasting ranges from several days to a few weeks of complete abstinence from food, and only water is allowed (Ref). However, you shouldn’t fast for more than 2-3 days without a healthcare provider. During water fasting, you are allowed to drink only 2-3 liters of water for 24 hours.

People may undergo water fasting for the following reasons:

  • To lose weight.
  • Prior to medical procedures such as surgery in certain conditions.
  • For religious and spiritual reasons.
  • Water fasting for detoxification.
  • For its health benefits.

Should I take vitamins while water fasting?

Taking vitamins during fasting is a controversial question as there are two different points of view about taking vitamins during fasting.

The first one assumes that vitamins are important during fasting to supply cells with the nutrition they need to function optimally. Accordingly, it is assumed that taking vitamins will not break your fasting. However, you should avoid vitamins with high calories such as those containing sugar or any carbohydrates.

In contrast, another point of view, which is more common, assumes that you shouldn’t take vitamins during water fasting. This is based on the following:

  • Taking vitamins during fasting could decrease the health benefits of fasting.
  • The main principle of fasting is to allow your body to consume internal sources of energy by breaking down stored fats and carbohydrates. So, vitamin supplements are better to be avoided during fasting.
  • Breaking down the endogenous fats during fasting could release the entrapped fat-soluble vitamins your body needs. So, you don’t have to take vitamin supplements during fasting.
  • Under fasting conditions, higher absorption rates of fats-soluble vitamins released from the breakdown of stored fats are expected.
  • For water-soluble vitamins, even if your body doesn’t store this type of vitamin, most people could maintain sufficient levels of water-soluble vitamins during short-term water fasting.
  • Sometimes taking vitamins on an empty stomach, during fasting, could lead to stomach upset, nausea and sometimes vomiting.
  • Fat-soluble vitamins should be taken with fatty meals to be absorbed, therefore you can’t take fat-soluble vitamins during water fasting. They will not be absorbed and thus administration with no benefits.
  • Some vitamins such as gummy vitamins often contain gelatin, collagen, and also sugar or artificial sweeteners. Therefore, such vitamins could break your fast and should be avoided while fasting.

In conclusion, the matter of whether or not taking vitamins while fasting is OK is not always a black-or-white answer.

As your body doesn’t store water-soluble vitamins, you can take water-soluble vitamins while fasting. These vitamins are soluble in water and have no need for food to be absorbed. Also, water-soluble vitamins are better to be taken on an empty stomach.

In contrast, you should avoid taking fat-soluble vitamins while fasting. As your body consumes the stored vitamins in the liver and fatty tissue. Also, these vitamins cannot be taken without foods especially fatty foods for best absorption.

Does water fasting cause vitamin deficiency?

In contrast to the expected effect that water fasting could lead to vitamin deficiency, studies have reported that water fasting could increase the blood levels of fat-soluble vitamins with no effect on blood levels of water-soluble vitamins. However, this effect is reported with water fasting for a short time (up to 10 days).

During fasting, your body gets the required energy from the breakdown of fatty tissue, as a result, fat-soluble vitamins are released into your blood. In contrast, water-soluble vitamins are not stored in your body.

A study published in 2022 showed that:

  • Complete fasting for 10 days leads to increased blood levels of fat-soluble vitamins, especially vitamins A, E, and D.
  • No increase in water-soluble vitamins was reported while water fasting.
  • In addition, the levels of sodium and chloride were significantly reduced.
  • The authors attributed the increased levels of fat-soluble vitamins to the fact that vitamins are released from stored fatty tissue during fasting to maintain vitamin nutrition of blood and other tissue.

A mother study provide similar results and confirmed that fasting leads to an increase in blood levels of vitamin D with no increase in blood levels of vitamin B12.

Tips to take vitamin supplements during water fasting

In case you are prescribed vitamin supplements during fasting for any purpose, it is important to take vitamins with certain precautions as follows:

  • You have to consult your doctor about the optimum dose and regimen for vitamin administration while you are fasting.
  • You have to opt for vitamins with zero calories or low calories.
  • Fat-soluble vitamins should be avoided during fasting and are allowed only with meals.
  • Water-soluble vitamins can be taken with water.
  • Avoid taking vitamin B-complex without foods. It can make you feel nauseous when you take it without food.


1. Can I drink coffee on water fasting?

Yes, you can drink coffee, but black coffee is the best with low or limited calories.

The main point of water fasting is to stop eating or drinking any source of calories. Therefore, if you need to drink coffee, you should take it back and avoid any sugar during fasting.

2. Can I take my medicine while water fasting?

Yes, you can take your medications while fasting.

In case you are fasting targeting water loss, not for religious purposes, taking your medications will not break your fast. However, it is important to avoid medications with high calories. You have to ask your healthcare provider about suitable alternatives if you used medications with high calories.

3. How long can you water fast?

Water fasting can last a few days to a few weeks. However, it is not recommended to fast for more than 2-3 days without medical supervision. Long fasting could be combined with a higher risk of health problems.

4. Can I take vitamin D while fasting?

No, you shouldn’t take vitamin D while fasting.

Vitamin D is a fat-soluble vitamin and needs to be taken with fatty foods to be best absorbed. Therefore, you should avoid vitamin D and all other vitamins especially fat-soluble vitamins during water fasting.

5. Should I take vitamins after water fasting?

Yes, it is better to take vitamins with the first food you take after fasting.

Under this condition, higher absorption of the administered vitamins is expected due to the deficiency during the fasting period. Also, taking vitamins with food could help you to avoid stomach upset associated with vitamin administration.

6. What should I monitor while fasting?

During Fasting, it is important to monitor your blood glucose levels. Hypoglycemia may result in serious complications.

Electrolytes such as sodium, potassium, and other important electrolytes should be monitored carefully while fasting. A decrease in such electrolytes could be accompanied by serious adverse effects.

7. What are the 2 types of vitamins and which are in each category?

Vitamins are organic supplements that your body needs in small quantities for normal cell function, growth, and development.

Vitamins are classified into two main categories. as the following:

Fat-soluble vitamins:

These vitamins include vitamins A, K, E, and D.

Your body stores the fat-soluble vitamins in the liver and fat tissues.

Fat-soluble vitamins contain fat-soluble ingredients accordingly, these vitamins should be administered with fatty meals for best absorption.

Water-soluble vitamins:

This includes vitamin C and all vitamins B (B1, B2, B6, B12, Pantothenic acid, biotin, and folic acid). These vitamins cannot be stored in your body and are eliminated in water through the kidney. Accordingly, you may need a regular supply of water-soluble vitamins as you have no stored water-soluble vitamins in your body.