Supplements

Should You Take Vitamins on an Empty Stomach?

Written by Lauren Manaker, RDN, CLE
Medically Reviewed by Felicia Newell, M.S., RDN

December 22, 2023

Vitamins play a crucial role in maintaining overall health and well-being—from boosting immunity to regulating gene expression. Whether you religiously take a daily multivitamin or have a specific vitamin regimen, understanding the best way to consume these essential nutrients is key. As a registered dietitian of over 20 years, there's one common question that I get from clients: Is it better to take vitamins on an empty stomach or with food?

In this blog, we'll explore the science behind taking vitamins on an empty stomach, the specific vitamins that can be taken without food, and those that are best absorbed when consumed with a meal. Let's get into it.

Table Of Contents

But First: The Difference Between Water-Soluble & Fat-Soluble Vitamins

Before exploring this topic further, there are two categories of vitamins you should know about: water-soluble vitamins and fat-soluble vitamins.

Water-soluble vitamins, such as vitamin C and B vitamins, dissolve in water and are not stored in the body. And as the name implies, these vitamins are also fine to drink with just water (i.e. they don’t need to be taken with food!).

On the other hand, fat-soluble vitamins, such as vitamins A, D, E, and K, are stored in the body's fatty tissues. These vitamins are best taken with a small amount of healthy fat (think: chia seed pudding, a salad with avocado or an olive oil drizzle, or even a scoop of MCT powder).

Here’s a complete list of water-soluble and fat-soluble vitamins:

Water-Soluble Vitamins

  • Vitamin C
  • Vitamin B1 (Thiamine)
  • Vitamin B2 (Riboflavin)
  • Vitamin B3 (Niacin)
  • Vitamin B5 (Pantothenic Acid)
  • Vitamin B6
  • Vitamin B7 (Biotin)
  • Vitamin B9 (Folate)
  • Vitamin B12

Fat-Soluble Vitamins

  • Vitamin A
  • Vitamin D
  • Vitamin E
  • Vitamin K

So, Which Vitamins Can I Take on an Empty Stomach?

In a pinch and need to take your vitamins without food? You’re in luck…certain vitamins—namely water-soluble vitamins—are better absorbed when taken on an empty stomach. (This means they won’t cause nausea or an upset stomach .)

These water-soluble vitamins include vitamin C and all eight B-complex vitamins: thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate (B9), cobalamin (B12). 

When taken in the morning on an empty stomach, these vitamins can be absorbed more efficiently in the small intestine, ensuring that your body receives the maximum benefit from supplementation (1). Vitamin C, in particular, is known to be well tolerated when taken on an empty stomach.

Certain minerals may be best taken on an empty stomach too. Iron is one nutrient that, when taken in supplemental form on an empty stomach, may result in more of the nutrient being absorbed as opposed to when it is taken with food (2). However, taking iron on an empty stomach may cause digestive upset in certain people. If this is the case for you, try taking iron with foods such as vitamin C, which increases iron absorption.

Many herbal supplements may be well-tolerated on an empty stomach as well.

Why It’s Better to Take Some Vitamins on an Empty Stomach

The process of vitamin absorption is complex and can be influenced by various factors…

When it comes to taking vitamins on an empty stomach, the primary reason is to optimize their absorption. Absorption is influenced by the digestive process, which starts in the stomach. 

NativeNote: Taking certain vitamins on an empty stomach ensures that they are not competing with food for digestion and absorption. This allows the body to focus on breaking down and absorbing the vitamins more efficiently.

Benefits of Taking Vitamins on an Empty Stomach

Taking vitamins on an empty stomach offers three potential benefits…

  • It allows for quicker and more efficient absorption of water-soluble vitamins.
  • It reduces the likelihood of interactions between certain vitamins and minerals and the components of food.
  • It may help prevent potential gastrointestinal discomfort that can occur when taking certain vitamins with food.

However, this doesn’t mean that all vitamins should be taken on an empty stomach. Just some of them. Keep reading to learn which ones to take with and without a meal.

Which Vitamins Should I Take With Food?

There are a handful of vitamins that may result in uncomfortable stomach pain when taken on an empty stomach….

The four fat-soluble vitamins—vitamins A, D, E, and K—need to be taken with a meal containing fat in order to aid their absorption. Additionally, taking these vitamins on an empty stomach can sometimes lead to stomach cramps, nausea, or heartburn (3).

Zinc is another supplement that should be taken with food. Taking a zinc supplement on an empty stomach has been shown to have the side effect of an upset stomach. For those with a zinc deficiency, it’s best to take your supplement with food.

Because many multivitamins contain fat-soluble vitamins, taking these supplements on an empty stomach isn’t recommended either.

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Two Other Factors to Consider When Taking Vitamins

When deciding whether to take vitamins on an empty stomach or with food, there are a few additional factors to consider…

Is the Supplement Time Released?

Time-release or extended-release supplements are a specialized form of dietary supplements designed to gradually release nutrients over an extended period, typically several hours. The primary benefit of these supplements is that they maintain consistent levels of the nutrients in your bloodstream, potentially optimizing their effectiveness. They can be particularly beneficial for nutrients that the body utilizes quickly, such as Vitamin C and B-complex vitamins. 

Regarding the consumption of time-release or extended-release supplements on an empty stomach, it's a topic that requires individual consideration. As these supplements are designed to release nutrients gradually, taking them without food may potentially allow for optimal absorption. Yet, similarly to standard supplements, the fat-soluble and water-soluble distinction is essential.

Is the Food/Drink You’re Taking It With a Nutrient Absorption Blocker?

Additionally, certain substances found in food and drinks, known as nutrient absorption blockers, can interfere with the absorption of vitamins. These include caffeine, alcohol, activated charcoal, and certain medications. It's important to be mindful of these factors and adjust your vitamin intake accordingly.

Here’s a look into each one…

Caffeine

Caffeine can inhibit the absorption of certain minerals, including iron and calcium. One study found that drinking a cup of coffee reduced iron absorption by 39%, and drinking green tea reduced iron absorption by a whopping 64% (4). Caffeine also increases the urinary excretion of some nutrients, such as B vitamins and potassium, potentially leading to deficiencies over time. If you are going to consume caffeine, ensure that it is at least 2 hours before or after taking any of the aforementioned supplements.

NativeNote: You should also be mindful to take iron supplements at least 2 hours apart from calcium supplements or high-calcium foods since they compete for the same receptors in your body and can inhibit absorption.

Alcohol 

Alcohol can also interfere with the absorption of vitamins. This is because alcohol can disrupt the normal functioning of your digestive system. Most notably, excessive consumption of alcohol can lead to a deficiency in vitamin B1 (thiamine), which plays a crucial role in converting food into energy. 

Activated Charcoal 

Activated charcoal, often used in detoxification processes, can also interfere with nutrient absorption. It functions by trapping toxins and chemicals in its tiny pores. However, this trapping mechanism doesn't discriminate between harmful substances and essential nutrients, potentially leading to a decrease in nutrient absorption.

Certain Medications

Certain medications can also interfere with nutrient absorption. Antibiotics, for example, can disrupt the gut microbiota balance, which plays a vital role in nutrient absorption. Antacid drugs used to control heartburn and acid reflux can impair the absorption of vitamin B12, calcium, iron, and magnesium (5, 6).

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Therefore, it's crucial to be aware of these potential interactions and to consult with a healthcare provider about the best time to take your supplements in relation to these substances, ensuring optimal absorption and effectiveness.

Frequently Asked Questions About Vitamins

While fasting, the intake of vitamins can be a nuanced matter. Fasting generally implies that no food should be consumed, which can complicate the absorption of certain vitamins. Fat-soluble vitamins like A, D, E, and K require fat from food for optimal absorption. Thus, taking these vitamins while fasting may not assure their full effectiveness. On the other hand, water-soluble vitamins such as vitamin C and B-complex vitamins might be better tolerated on an empty stomach.

However, some individuals could experience stomach upset or discomfort. It's important to note that the impact of fasting on vitamin absorption can vary significantly based on individual physiological factors. Therefore, if you're planning to take vitamins while fasting, it's always best to consult with a healthcare provider to determine the best course of action for your specific health needs.

Lauren Manaker
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Lauren Manaker

Lauren Manaker is an award-winning registered dietitian (RDN), certified lactation educator (CLE), author, and speaker with over 20 years of experience. She earned her BS in Food Science and Human Nutrition from the University of Florida (go Gators!) and an MS in Clinical Nutrition from Rush University in Chicago.

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    Medical Disclaimer

    This content is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of such advice or treatment from a personal physician. All readers/viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. Neither Dr. Chad Walding nor the publisher of this content takes responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All viewers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians before beginning any nutrition, supplement, or lifestyle program.

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