Do Vitamins Break A Fast?

The practice of fasting has been around for thousands of years, and is common in nearly every major religion.

However, in recent years, many people have been choosing to fast with the aim of improving their health, rather than in a religious capacity.

A type of fasting called intermittent fasting has become one of the world’s most popular wellness trends.

Intermittent fasting is an eating pattern that involves cycling between periods of fasting and periods of time where you can eat. For example, one method restricts your daily eating period to 8 hours, with a fast of 16 hours in between.

Most people engage in intermittent fasting as a weight loss method. And while it does show promise for weight loss and maintenance, there are other health benefits that have been linked with intermittent fasting too. (Source)

Research also shows that intermittent fasting may play a role in:

• Protecting against type 2 diabetes by reducing insulin resistance (Source)
• Reducing inflammation (Source)
• Improving heart health (Source)
• Maintaining brain health (Source)

Can I Take Vitamins While Fasting?

While food is an obvious no-no during the fasting window, there are often some questions around liquids and even more confusion when it comes to supplements.

In most non-religious fasts, water is considered acceptable to consume during the fasting window and some people also allow unsweetened black coffee and plain teas.

But what about vitamins?

Whether or not your vitamin supplement will break your fast largely depends on the type of supplement you’re taking.

As a rule of thumb, if your vitamin supplement contains calories, it could break your fast.

In some cases, even supplements without calories can break a fast if they contain sweeteners that provoke an insulin response, as is the case with some gummy supplements.

It’s also important to consider that some vitamins are better taken alongside food. For example, fat-soluble vitamins (vitamins A, D, E, and K) are recommended to be consumed alongside a meal that contains some fat in order to maximize absorption.

In some cases, B vitamins are better taken with food too, as they can cause nausea for some people on an empty stomach.

Let’s take a look at what vitamins can and can’t be taken during the fasting window in more detail.

It is important to note that fasting rules can vary depending on the kind of fast being undertaken. People who are fasting for religious reasons should speak with their religious leader if they have any confusion regarding what can and can’t be included in their fast, and those who are fasting for medical reasons, or under the guidance of a healthcare professional, should consult their practitioner.

Supplements To Avoid During A Fast

Gummy Vitamins

Yes, gummy vitamins taste good, but that’s because they usually include sugar. Sugar contains calories and so will bring you out of a fasted state.

There are some no-calorie gummy vitamins available, however, these often still contain sweeteners, many of which can trigger an insulin response that can affect your fasting state.

If you are a big fan of gummy vitamins, waiting to take them during your eating window is best.

Multivitamins

Most pure-form vitamins won’t break a fast, but taking them on an empty stomach isn’t best for absorption.

Water soluble vitamins (B vitamins and vitamin C) are okay to take without food as they only need water to be optimally absorbed and therefore food is not required for absorption. However, some people can experience nausea when taking B vitamins on an empty stomach. In this case, it is better to take them with some food.

Fat-soluble vitamins (vitamins A, E, D, and K) on the other hand require fat to be present in order to be absorbed properly. So these vitamins need to be taken alongside a meal containing some fat. (Source)

Multivitamins may not have a caloric tag, but because they contain fat-soluble vitamins and often some other nutrients that are best absorbed with food, taking your multivitamin supplement during your feeding window will allow for more effective nutrient absorption.

Multinutrient Powders

Multinutrient powders, such as green powders and red powders, often contain a small number of calories per serving because their ingredients provide small amounts of carbohydrates, fiber, and protein. Because of this caloric content, they would be considered to break a fast. 

Similarly to multivitamins, some of the nutrients in these powders are better absorbed with food.

So always wait until your feeding window to enjoy your greens powder. 

Protein Powder

Protein powders should definitely be avoided while fasting.

Protein powders contain a substantial amount of calories per serving due to their protein content, and so will break a fast if consumed during the fasting window.

Keep your protein shakes for your eating period.

BCAAs

Branched-chain amino acids, or BCAAs, are the amino acids leucine, isoleucine, and valine, and can be consumed as a supplement. 

BCAAs are often consumed by athletes due to their purported benefits for muscle growth and performance.

If you drink a BCAA supplement during a fast, then technically you’re not truly fasting as the amino acids will trigger an insulin response. (Source)

However, BCAAs won’t disrupt your fast in the same way as eating a meal.

Whether you want to take BCAAs while fasting depends on the purpose of your fast and how strictly you are fasting.

Supplements That May Be Taken During A Fast

Electrolytes

Electrolytes are essential minerals that carry an electric charge when dissolved in a fluid and are found in our blood, sweat, and urine. Sodium, potassium, chloride, and calcium are all electrolytes. (Source)

They play a key role in hydration and other body processes, including the nervous system and muscle function.

Athletes often supplement with electrolytes to replenish themselves after excessive sweating. They are also often taken by people when ill to make up for electrolytes lost through vomiting and diarrhea.

There are many sugary electrolyte drinks and sports drinks available. While these are unsuitable during fasting due to their calorie content, electrolytes in their pure form contain no calories. They so can be taken during your fasting period without breaking your fast.

Water Soluble Vitamins

Water soluble vitamins in their pure form do not have any caloric value and so will not break your fast.

As mentioned, these vitamins only need to be taken with water in order to be absorbed by the body and so are suitable to be taken during the fasting window if required.

However, some people do experience nausea when taking vitamins on an empty stomach. If this is the case for you, try taking them with some food instead.

Creatine

Creatine is one of the most popular supplements worldwide, and it is frequently used by athletes to improve power, strength, muscle mass, and performance. (Source)

Pure creatine is safe to take during your fasted window as it contains no calories and should not affect your blood sugar levels. However, it’s important to select a creatine product free from sweeteners and other additives.

For those that train during their fast, creatine can help to support physical activity and increase energy supply since your body cannot depend on the breakdown of carbohydrates to provide energy in a fasted state.

However, some people do experience digestive issues when taking creatine on an empty stomach. If you find you experience stomach upset when taking creatine during your fasting window, you may prefer to take it alongside some food.

Iron

While many people get adequate iron from their diet, if you’re someone who menstruates or struggles with low iron stores, you might take an iron supplement and wonder whether it is suitable to take while fasting – yes, pure iron supplements can be taken without breaking your fast.

In fact, iron is best absorbed on an empty stomach in combination with vitamin C, so taking it during periods of fasting or before meals with a pure vitamin C supplement is ideal. (Source)

However, some people can experience minor digestive upset or constipation with iron tablets. If you find this to be the case, there are non-constipating iron tablets on the market, or you can consume your iron supplement with a meal during your feeding window.

Some Probiotics

Some probiotic supplements can be taken during fasting periods and will not break a fast, as they have negligible to no caloric content.

There are certain strains of probiotics that are recommended to be taken on an empty stomach and so are best taken during your fasting window. Other strains are best taken with food and so are best taken with a meal.

Check the label for your specific probiotic supplement to see when is best to take them.

Similar to multivitamins, watch out for probiotic supplements that may contain calories and sugar, such as gummies or those in dietary powders, as these can’t be taken while fasting and would break your fast.

In Summary

With intermittent fasting becoming so popular in recent years, so too have concerns over what does or doesn’t constitute breaking a fast.

While food is a definite no-no during the fasted window, and most drinks are off the cards except for water, black coffee, and plain tea, in most cases. There can be confusion when it comes to supplements.

As a general rule, if the supplement has no calories, no sugar, and no sweeteners, it won’t break your fast. 

Supplements to avoid during your fasted window include:

• Gummy vitamins
• Multivitamins
• Green powders and other multi-nutrient powders
• Protein powder
• BCAAS

And supplements you can still consume while fasting include:

• Pure electrolytes
• Pure water-soluble vitamins
• Pure creatine
• Pure iron
• Some probiotics

That being said, fasting rules can vary depending on the kind of fast being undertaken.

People who are fasting for medical reasons or under the guidance of a healthcare professional should consult their practitioner if they have any concerns about what can and can’t be included in their fast.

Lucy Brennan, ANur, BSc

Lucy Brennan is a registered associate nutritionist (ANutr) and freelance writer specializing in health, nutrition and wellness content.  She holds a BSc. (First Class Hons) in Public Health Nutrition and has over 4 years’ experience working in health communication, which is where her passion lies.

She has worked in roles with The Irish Food Board and FleishmanHillard PR, on their healthcare team, working with national and international health companies. Using this experience, Lucy now writes content in a freelance capacity. Lucy is dedicated to providing evidence-based content that is both engaging and accessible and inspires readers to make informed choices regarding their health.