Drug-Nutrient Interactions: Understanding the Basics

Kelly C. Heim, Ph.D. and Heidi Harris, RD-N, CD-N, LD-N

One common question we get a lot is, “What are Drug-Nutrient Interactions?” So, we decided to create a Drug-Nutrient Interaction Checker to help you learn about how supplements may interact with prescription or over-the-counter drugs you take. I mean, let’s be honest, it feels like almost everyone has a pile of over-the-counter medications in our toiletry cabinet somewhere, right? You may not realize it, but those medications may interact with nutrients and other ingredients in dietary supplements.

Some drugs can reduce nutrient absorption, while others may interfere with how well a drug works.¹ I’m going to first introduce you to the different types of drug-nutrient interactions, including examples of how they might play out in real life. Let’s get started!

Drug-Nutrient Interactions vs. Depletions
Okay, before we dive in, I want to clear the air, because I get that this may be confusing. First, drug-nutrient interactions is a bit of a misnomer here because we’re not just talking about nutrients (like vitamins and minerals). Drugs can also interact with herbs and other active ingredients in dietary supplements. For simplicity, we’ll use the term “nutrient” to include all types of dietary supplement ingredients.  

A drug-nutrient interaction occurs when a nutrient, like those found in dietary supplements change the way your body absorbs, processes or responds to a medication.^3‡  

Drug-nutrient depletions are also interactions, but occur when a medication reduces your body’s ability to absorb, process, store or use a nutrient.² Sit tight - we’ll cover each of these.

There are two main types of interactions: pharmacodynamic and pharmacokinetic.^‡ Those are a mouthful, but knowing the basics can help you better understand how to interpret the confusing information you might find on this topic. If you’re still not sure, it’s always best to have conversation with your healthcare practitioner, who can help guide you on your supplement journey. Now, let’s discuss these two types of drug-nutrient interactions and their specific examples.

There are two main types of interactions: pharmacodynamic and pharmacokinetic.^‡ Those are a mouthful, but knowing the basics can help you better understand how to interpret the confusing information you might find on this topic. If you’re still not sure, it’s always best to have conversation with your healthcare practitioner, who can help guide you on your supplement journey. Now, let’s discuss these two types of drug-nutrient interactions and their specific examples.

Pharmacodynamic Interactions: 
Pharmacodynamic drug-nutrient interactions modify the pharmacological or the clinical effects of a medication. In other words, the supplement changes “what the drug does to the body.”⁴ This pretty much means that the effect of a drug may not be the same because you took a supplement. It might become stronger, weaker or produce more side effects. This can happen in three different ways: atagonistic, additive or synergistic.⁴

Antagonistic
An antagonistic drug-nutrient interaction occurs when a nutrient or ingredient in a supplement counteracts the function of a drug, so that it can’t work as effectively as it should.⁵ A good example of an antagonistic pharmacodynamic drug-nutrient interaction is Vitamin K and warfarin (Coumadin).

Vitamin K (which is found in our Synergy K) supports the normal process of blood coagulation.  Coumadin inhibits coagulation by inhibiting vitamin K activation.⁶ This is why doctors recommend avoiding supplemental Vitamin K and being careful with vitamin K-rich foods, such as dark leafy greens (like kale or spinach), which may also make warfarin less effective.⁶  This is why it’s important to disclose the supplements you take with your health care practitioner. ^‡ 

Additive
An additive drug-nutrient interaction is pretty much exactly what it sounds like. This occurs when a drug and a nutrient or ingredient in a supplement have similar functions and taking them together simply makes the effect stronger. By combining them, you’re just “adding” their effects. The outcome exceeds the anticipated result, as if you “doubled up” on one of them.⁵ The following are relevant examples, however, we still recommend discussing this information with your health care practitioner:

For example, the drug amiodarone contains 37.3% iodine and can increase iodine levels. Taking iodine, which is in our potassium iodide, along with this drug could result in excess iodine in your body.⁷ 

Similarly, velvet bean extract, which is found in our Pure Encapsulations® DopaPlus, contains L-DOPA.   So does Sinemet, a neurological drug. Taking both at the same time gives you a slightly bigger dose of L-DOPA than your doctor may have prescribed.⁸

L-arginine is an amino acid that helps maintain healthy blood flow by supporting the relaxation of blood vessels   If you take lisinopril, a drug which may lower blood pressure, with a high dose of L-arginine, it could cause undesirable symptoms like faintness, fatigue or dizziness.⁹  It’s important to consult your health care practitioner to decide whether this combination is safe, and whether to monitor your blood pressure.

L-arginine is an amino acid that helps maintain healthy blood flow by supporting the relaxation of blood vessels. If you take lisinopril, a drug which may lower blood pressure, with a high dose of L-arginine, it could cause undesirable symptoms like faintness, fatigue or dizziness.⁹ It’s important to consult your health care practitioner to decide whether this combination is safe, and whether to monitor your blood pressure.

Synergistic Interaction
A synergistic interaction is like an additive interaction, only stronger. This is when a drug-nutrient combination produces an effect that greatly exceeds the effect of either agent alone.⁵ You can think of it as 1+1=3. They work together (synergy), but this means that their impact is greater than the sum of their individual effects. There is relatively little research documenting synergistic drug-nutrient combinations, and it’s hard to tell the difference between additive and synergistic in real life situations.

Theoretically, combining L-Arginine with blood pressure-lowering drugs could either produce an additive or a synergistic interaction (whether it’s additive or synergistic is impossible to predict without clinical trials on the combination, which are currently lacking). A synergistic interaction occurs when the combination causes a greater effect than either the drug or supplement alone. 

Why is this important?  Well, although these interactions are unlikely to be noticeable or cause harm, they are pretty unpredictable, and everyone is different in how they respond to medications and combinations. So, it’s critical that you’re aware of the possibility that this interaction may occur and ask your health care provider whether L-arginine is right for you.

With so many over-the-counter products and prescription drugs many of us may have in our medicine cabinets, it is important to educate ourselves regarding which nutrients and ingredients in supplements may be right for us, what to avoid, and the importance of talking to your health care practitioner when making these decisions.

Pharmacokinetic Interactions
Let’s talk about the pharmacokinetic drug-nutrient interactions. This is when a supplement alters the absorption, distribution, metabolism or elimination of a drug, or vice versa.⁴ Let’s dive into the four types of pharmacokinetic drug-nutrient interactions and discuss some specific examples:

Absorption
This type of drug-nutrient interaction reduces the absorption of either the supplement or drug. This may reduce the effectiveness of the drug or nutrient by interfering with its uptake from your digestive tract.⁴

Some drugs reduce the body’s ability to absorb a nutrient, especially with prolonged use.^10-12 For example, metformin (Glucophage) may reduce the absorption of Vitamin B12,  possibly by interfering with the acidity of the stomach and production of intrinsic factor, a glycoprotein required for absorption of Vitamin B12.^10,12‡

Watching vitamin B12 status in individuals who are taking metformin over a long period of time may be appropriate.¹²  It might make sense to consider a Vitamin B12 supplement to help meet nutritional needs^.‡

Distribution
This type of pharmacokinetic drug-nutrient interaction causes a drug or nutrient to have trouble getting to an organ or tissue it needs to reach in order to produce its intended effects.³

For example, certain dietary amino acids, including branched chain amino acids, compete with Levodopa, a drug, for entry into the brain. Taking both at the same time could potentially make the drug less effective.⁸

Metabolism
This type of pharmacokinetic drug-nutrient interaction alters the metabolism of either the drug or the nutrient, potentially changing the amounts in the body.³ Certain nutrients, herbs and other dietary supplement ingredients have the potential to promote, slow down and even prevent drugs from working as they should.¹

For example, drinking green tea daily for two weeks speeds up the metabolism of lisinopril (a blood pressure lowering drug) by reducing the levels of the drug in the bloodstream by as much as 85%.¹³ This interaction could make this drug less effective in lowering blood pressure.   

That’s why it may be beneficial to talk with your healthcare provider if you’re taking a product similar to Pure Encapsulations® Green Tea Leaf Extract and a medication similar to lisinopril.

Elimination
This is the last type of pharmacokinetic drug-nutrient interaction. It causes the body to eliminate a drug or nutrient too quickly (making it less effective) or too slowly (potentially building up to unsafe levels in the body).³

A good example of this type of drug-nutrient interaction may occur with thiazide diuretic medications, like hydrochlorothiazide, which may accelerate the urinary loss of potassium.¹⁴ This is also an example of a drug-induced nutrient depletion. The drug package insert provides instructions on maintaining adequate potassium in patients taking the drug.¹⁴

Drug-Induced Nutrient Depletions: 

Before we part ways, let’s briefly talk about two examples of pharmacokinetic interactions that may increase nutrient needs. These are called drug-induced nutrient depletions.  While these interactions don’t really “deplete” the nutrient entirely, they can impair the body’s ability to make or absorb a nutrient. Here are a couple of examples:

• Studies have suggested that statin medications, which are used to lower cholesterol, may lead to lower levels of coenzyme Q₁₀ (CoQ₁₀), an antioxidant and core component of cellular energy production ^22-24‡.
  • The body normally makes its own CoQ₁₀ using an enzyme called HMG CoA reductase (this is the same enzyme that helps make cholesterol).
  • Statins block this enzyme, which may lead your body to make less cholesterol and CoQ₁₀. ^‡
  • A CoQ₁₀ supplement may be helpful in repleting this nutrient when taking statins.^15‡
• Nexium (esomeprazole) is a popular proton-pump inhibitor that reduces stomach acid and helps to manage abdominal discomfort associated with excess acid production. But did you know that vitamin B12 and iron rely on stomach acid for absorption? Prilosec and other proton-pump inhibitors reduce the absorption of these nutrients by making the stomach less acidic.¹¹

If you take these drugs regularly, it’s important to talk to your HCP about when a supplement might be helpful.

We Developed a Checker to Support You!
So how does one figure out whether their medications or nutrients could potentially interact? That’s a great question and the reason we developed our new Drug-Nutrient Interaction Checker! The Drug-Nutrient Interaction Checker looks for potential clinically significant interactions between prescription or over the counter medications and active ingredients present in dietary supplements based on commonly used doses. You can now enter the name of your medications (over-the-counter and prescription) into the search box and instantly receive information regarding potential interactions with supplements in the Pure Encapsulations® product line. The Drug-Nutrient Interaction Checker does not include interaction or depletion information from off-label use of a nutrient or ingredient (such as exceeding the recommended dose on the label). The information is easy to understand, updated regularly and linked to supporting research studies if you want to dig deeper.  What are you waiting for? Try our new Drug-Nutrient Interaction Checker today!

This article and the Drug-Nutrient Interaction Checker is for educational and general wellness information purposes only. It is not medical advice nor intended to replace the advice of your healthcare professional. Please consult your healthcare professional with any questions regarding this article or your use of the Drug-Nutrient Interaction Checker.

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1. Drug – Nutrient Interactions - Oklahoma State University. (2019, October 9). Extension.okstate.edu. https://extension.okstate.edu/fact-sheets/drug-nutrient-interactions.
2. Carolina, C. M. M., PharmD, BCACP, BCGP Assistant Professor of Pharmacy Wingate University School of Pharmacy Wingate, North. (n.d.). Drug-Induced Nutrient Depletions: What Pharmacists Need to Know. Www.uspharmacist.com. https://www.uspharmacist.com/article/druginduced-nutrient-depletions-what-pharmacists-need-to-know.
3. Drug interactions | Pharmacology Education Project. (n.d.). Pharmacologyeducation.org. https://www.pharmacologyeducation.org/clinical-pharmacology/drug-interactions.
4. Difference between Pharmacokinetics and Pharmacodynamics | PharmaEducation. (2019, May 19). Pharmaeducation.net. https://pharmaeducation.net/difference-between-pharmacokinetics-and-pharmacodynamics/
5. Pharmacodynamics | Pharmacology Education Project. (2019). Pharmacologyeducation.org. https://www.pharmacologyeducation.org/pharmacology/pharmacodynamics.
6. Office of Dietary Supplements - Vitamin K. (n.d.). Ods.od.nih.gov. https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional.
7. Corderone (Amiodarone) [package insert]. Philadelphia, PA; Wyeth Pharmaceuticals Inc., 2004.
8. Sinemet (Levodopa-Carbidopa) [package insert]. Whitehouse Station, NJ, Merck & Co, Inc.
9. Komers R, Komersova K, Kazdova L, Ruzickova J, Pelikanova T.. J Hypertens. 2000 Jan;18(1):51-9.
10. Kim J, Ahn CW, Fang S, Lee HS, Park JS.. Medicine (Baltimore). 2019 Nov;98(46):e17918.
11. Nexium (Esomeprazole) [package insert]. Wilmington, DE; AstraZeneca Pharmaceuticals LP, 2015.
12. Glucophage (Metformin) [package insert]. Princeton, NJ; Bristol-Myers Squibb Company, 2017.
13. Misaka S, Yatabe J, Müller F, et al. Green tea ingestion greatly reduces plasma concentrations of nadolol in healthy subjects. Clin Pharmacol Ther. 2014 Apr;95(4):432-8.
14. Cohn JN, Kowey PR, Whelton PK, Prisant LM. New Guidelines for Potassium Replacement in Clinical Practice:A Contemporary Review by the National Council on Potassium in Clinical Practice. Arch Intern Med.2000;160(16):2429–2436. 
15. Qu H, Guo M, Chai H, et al.. J Am Heart Assoc. 2018 Oct 2;7(19):e009835.

 

Kelly C. Heim, Ph.D. (co-author)
Kelly C. Heim, Ph.D., is Senior Scientific Director, Pharmacology & Genomics for Pure Encapsulations and Douglas Laboratories, where he oversees the evidence-based development of educational resources. As a pharmacologist specializing in natural products, Dr. Heim is a published author and illustrator of various scholarly articles and book chapters on the pharmacology of flavonoids and other polyphenols.

Heidi Harris, RD-N, CD-N, LD-N (co-author)
Heidi is a Registered Dietitian, Certified Group Exercise Instructor and Certified Strength Train Coach. She has a wealth of clinical knowledge in community management, social engagements, and nutritional science, and is here to help answer questions and educate you on the most up-to-date nutritional information, all Purely for You!