Food and Drug Interactions
What is a food-drug interaction?
Food-drug interactions occur in a variety of ways. Some foods can alter a medication so it does not work normally either by increasing or decreasing its effectiveness. Foods can also heighten unwanted side effects. These interactions don’t just occur in prescription medications, but over the counter ones as well.
Food-drug interactions are still being studied, and it can be hard to actually prove an interaction. There are a number of interactions that we do know of, and it is important to educate others on what we do know.
**This article is meant for informational purposes. Please talk with your physician or a medical personnel before making any dietary changes**
Leafy greens and Coumadin
Coumadin (warfarin) was one of the first blood thinners that was prescribed to treat blood clots. The medication works by stopping the production of Vitamin K, an important component in making blood clotting proteins in the body. [1]
People taking Coumadin may have been told to avoid leafy greens like spinach, broccoli, kale, and Brussels sprouts because they contain high levels of Vitamin K. The truth is that leafy greens do not need to be completely eliminated from their diet, especially because they are good for you and have a lot of health benefits. Experts have found that it is important for a person on Coumadin to measure the amount of leafy greens they are eating everyday, and just keeping it consistent. Joel Fuhrman, MD, a highly rated physician best known for his nutritional advice, recommended that someone on Coumadin should be consuming one serving of salad and one serving of cooked greens everyday. He believes that improving overall health can reduce chances of blood clots, and could lead to safely discontinuing the medication for some people. [2] A person should check with their provider before following Dr. Fuhrman’s recommendations.
Clinical dietician at Penn Medicine, Fran Burke MS, RD, said during an interview that leafy greens and Coumadin is not an avoidance problem, but rather a consistency issue. He recommends 120 mcg of vitamin K for men 19 and older, and 90 mcg for women 19 and older.[3] Reaching for that goal each day is a great way to keep your intake consistent, and also encourages a healthier diet.
A study published by the Center for Integrative Healing and Wellness found that adding more vitamin K into a person's diet may actually help. The result of their study showed 50% of the subjects who added more vitamin K to their diets had more stable anticoagulation levels. [4] They also recommend 90 mcg for adult women and 120 mcg for adult men of vitamin K a day.
Coumadin is still being prescribed today, but there are a number of blood thinners now that do not interact with any foods. A person may want to ask their doctor about switching to an anticoagulant like Xarelto (rivaroxaban), Eliquis (apixaban), or Pradaxa (dabigatran). If you are taking Coumadin, make sure to talk to your provider first before you make a change to your diet.
MAOIs and tyramine
A monoamine oxidase inhibitor (MAOI) is a class of antidepressant that includes Marplan, Nardil, Emsam, and Parnate. The medication works by blocking an enzyme called monoamine oxidase which assists with breaking down excess tyramine in the body. [5] The blocking of this enzyme is what actually alleviates depression, but the problem is when it causes a buildup of tyramine in the body. Tyramine is involved in the regulation of blood pressure. Too much tyramine can cause dangerously high blood pressure. [6]
Foods high in tyramine include:
Strong cheeses like aged cheddar, Parmesan, Swiss, blue cheeses
Cured meats or smoked/processed meats like pepperoni, summer sausage, salami, bologna, hot dogs, and bacon
Pickled and fermented foods like kimchi, tofu, pickles, and sauerkraut
Dried and overripe fruits like raisins or prunes and overripe bananas
Yeast-extract spreads like marmite or sourdough bread
*Experts recommend avoiding high tyramine foods while on the MAOIs, but also 2-4 weeks after stopping the medication.
A person on an MAOI should be consuming freshly prepared food and avoiding leftovers. This is because higher tyramine levels are found in foods in the spoiling/aging process. Cheeses including American, cottage, ricotta, and cream cheese, are not as likely to have high levels of tyramine because they come from pasteurized milk. [7] Some other alternatives are: fresh, frozen, or canned meat/fish/poultry, non-cured bacon, fresh deli meats, soy milk, spreads not including Marmite or Vegemite. [8]
Luckily, MAOIs are not often prescribed anymore since there are many other antidepressants that don’t come with many dietary restrictions.
Grapefruit juice
Grapefruit juice interacts with a number of medications, because it changes the absorption rate of medications, and impacts the liver in a way that makes it harder for a drug to pass through the body. Some medications get broken down by an enzyme called CYP3A4, basically its job is to reduce the amount of medication allowed to enter the bloodstream. Grapefruit juice contains compounds called furanocoumarins which stops the enzyme from doing its job. [9] When this occurs, there is a chance that too much medication can enter the bloodstream leading to toxicity and other hazardous events.
The most affected drug class is probably the statins. Statins are used to lower cholesterol, some examples are Lipitor (atorvastatin), Mevacor (lovastatin), Zocor (simvastatin), Pravachol (pravastatin), and Crestor (rosuvastatin). Other medications like psychotropics (includes antidepressants, anti-anxiety, anti-psychotics, stimulants, and mood stabilizers) and some antihistamines like Allegra (fexofenadine) are also affected by grapefruit juice. Allegra is actually affected in the opposite way as the other two medication classes, less of the medication is able to enter the blood which reduces its effectiveness.
It’s worth mentioning that not all medications of a certain drug class will be affected the same. For example, a study from Harvard found that some statins were more affected by the juice than others. It should be noted that these studies were done using large amounts of furanocoumarins. The statins that were found to be most impacted were Lipitor, Mevacor, and Zocor. [10] Experts have said that it is alright to enjoy a small glass (8 ounces or less) of the juice from time to time, but just make sure and check with a doctor!
Thyroid medications and food
The American Thyroid Association has done extensive studies examining when the best time to take Synthroid (levothyroxine) is. They found that taking the medication in the morning 30-60 minutes before eating or drinking caffeinated beverages is ideal. [11] Remaining consistent when you take your medication is a good habit to form. Food can prevent the medication from absorbing correctly in your small intestine, reducing its effectiveness. [12] It is very important to get the full amount of medication in your system in order for your thyroid to work properly.
Antibiotics
There are a few warnings when it comes to mixing antibiotics with some food and beverages. The first interaction is alcohol of any kind. Although it may not directly alter the medication, drinking alcohol while sick interrupts the recovery process. You may be experiencing nausea while ill so adding alcohol on top of that greatly increases that nausea and possible vomiting. Alcohol also impairs a person's cognitive function and in some cases, antibiotics do too, combining the two could lead to dangerous activities. Completely avoiding alcohol while on antibiotics and about 48 hours after finishing the medication is key. [13] This rule is especially important when taking either Tinidazole or Flagyl (metronidazole) because these two medications are known to have very unwanted and dangerous side effects when combined with alcohol. This can include nausea, vomiting, sweating or flushing, extreme thirst, and headache. The reaction time is different in everyone but can last hours. [14]
Dairy products and fruit juices are another interaction. Experts say to delay consumption of dairy products and fruit juices by about 2-3 hours after taking an antibiotic although a small amount isn’t going to be a problem. [15] Dairy products contain high levels of calcium which will actually attach to the antibiotic stopping it from entering the bloodstream which prevents the medication from doing its job of fighting the infection. High acidity levels in fruit juices reduces the absorption of medication resulting in decreased effectiveness. [16]
It is also important to check with your provider or pharmacist on whether an antibiotic (or any new medication) should be taken with or without food as well!
Antibiotics, probiotics, and prebiotics
Antibiotics can interfere with the good and bad bacteria equilibrium in the GI tract, this is called dysbiosis. [17] This is why the condition known as “antibiotic-associated diarrhea” (AAD) can occur. This condition can be dangerous when there is a large amount of fluids and electrolytes lost. The best way to avoid this condition is to take a probiotic; it has been proven to be both a preventative and a treatment of AAD.
Probiotics and antibiotics work as partners. While the probiotic helps yield unwanted side effects, it also assists the antibiotic in fighting the infection. Antibiotics make changes to some of the bacteria in our gut microbiome, when paired with a probiotic those changes are minimized or prevented. [18]
Systematic review of studies done on probiotics and antibiotics revealed that the subjects who took both had better results. [19] The recommendation is to take a probiotic during the whole course of taking the antibiotic for the best outcome, but even if you start taking it a little later, it can certainly still help. [20]
For prebiotics, they are recommended to be taken after a person has finished their antibiotic treatment. This is because prebiotic foods are high in fiber, which can affect the body’s function to absorb the antibiotic correctly. [21] Prebiotics may help speed up the process of finding balance in the gut microbiome, it does this by nourishing the good bacteria. [22]
Foods with prebiotics include seeds, nuts, beans, and high fiber fruits and vegetables.
How to avoid interactions?
There are simple steps you can take to prevent an interaction. A pharmacist or technician should tell you if there are any serious food-drug interactions with your new medication, but if you do not get a chance to speak to one or if you do mail order, do not panic.
Be sure to read the prescription bottle when taking a new medication. The papers that come with your prescription are there for a reason; it is important to read all the warnings so you know what to look out for. This is the same for over the counter products.
Take your medication with a full glass of water, unless told otherwise by a healthcare provider. It’s important to drink the whole glass of water for many medications to work properly.
Avoid cutting and crushing of a medication unless instructed differently by a healthcare provider. Crushing or cutting a medication to put in food may reduce its effectiveness.
Always check with a healthcare provider before starting a new supplement while on medication. Supplements can alter the effects of some prescription medications.
Don’t be afraid to ask your doctor or pharmacist about a possible food-drug interaction. You should never feel ashamed by asking questions, especially when it comes to your health.
Management and understanding of food-drug interactions play a vital role in meaningful healthcare practices, allows medications to effectively do their job, and improves a patient's outcome and well-being.
How foods can boost the immune system:
Nutrients and plant bioactives have roles in supporting the immune system. We know that diet provides us with the proper nutrients that support the immune system, this occurs in a variety of ways.
The right nutrients energize the immune system to function
Regulates immune cell metabolism
Maintains the intestinal microbiome which modulates the immune system
An example of how foods can boost immunity would be a study which showed that a low number of micronutrients is linked with higher risk and severity of COVID-19
Research indicates that the plant-based diet contributes to lower chance of developing COVID 19 and less severe symptoms of the illness [23]
Immune system is best supported with the daily recommended amounts of essential and nonessential nutrients
The best way to support the immune system is to consume a variety of fruits, vegetables, nuts, seeds, and grains with the occasional consumption of meats, eggs, and dairy products. [24]
Be sure to eat foods high in flavonoids (berries, citrus fruits, cherries, and tea): research revealed that people who eat foods with high levels of flavonoids reduce risk of developing upper respiratory tract infections [25]
Make sure your diet includes oranges, kiwis, and red bell pepper: all of these foods are high in vitamin C which is known to boost the immune system although the specific reason is not yet known
References
1 Violi, F., Lip, G. Y., Pignatelli, P., & Pastori, D. (2016). Interaction Between Dietary Vitamin K Intake and Anticoagulation by Vitamin K Antagonists: Is It Really True?: A Systematic Review. Medicine, 95(10), e2895. https://doi.org/10.1097/MD.0000000000002895
2 Fuhrman, J. (2017, January 3). Taking warfarin (Coumadin®) doesn’t mean you should avoid green vegetables. Dr. Fuhrman. https://www.drfuhrman.com/blog/12/taking-warfarin-coumadin-doesnt-mean-you-should-avoid-green-vegetables
3 Medicine, P. (2022, May 3). The Truth About Blood Thinners, Leafy Greens, And Vitamin K. Pennmedicine.org. https://www.pennmedicine.org/updates/blogs/heart-and-vascular-blog/2015/june/consistency-not-avoidance-the-truth-about-blood-thinners-leafy-greens-and-vitamin-k
4 Almeida, F. (2023, March 23). Leafy greens are OK for people on warfarin. Center for Integrative Healing & Wellness. https://www.drfabio.com/healthblog/leafy-greens-are-ok-for-people-on-warfarin
5 Hall-Flavin, D. K. (2018, December 18). Avoid the combination of high-tyramine foods and maois. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/depression/expert-answers/maois/faq-20058035
6 Hall-Flavin, D. K. (2018, December 18). Avoid the combination of high-tyramine foods and maois. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/depression/expert-answers/maois/faq-20058035
7 “NEMO” team. (2020, July). Low tyramine diet - queensland health. https://www.health.qld.gov.au/__data/assets/pdf_file/0020/145802/oncol_maoi.pdf
8 “NEMO” team. (2020, July). Low tyramine diet - queensland health. https://www.health.qld.gov.au/__data/assets/pdf_file/0020/145802/oncol_maoi.pdf
9 Bushra, R., Aslam, N., & Khan, A. Y. (2011). Food-drug interactions. Oman medical journal, 26(2), 77–83. https://doi.org/10.5001/omj.2011.21
10 Harvard Medical School . (2020, June 14). Grapefruit juice and statins. Harvard Health. https://www.health.harvard.edu/heart-health/grapefruit-juice-and-statins)
11 Hofflich, H. (2013, June 21). Vol 6 issue 11 p.4. American Thyroid Association. https://www.thyroid.org/patient-thyroid-information/ct-for-patients/vol-6-issue-11/vol-6-issue-11-p-4/#:~:text=The%20absorption%20of%20levothyroxine%20in,erratic%20absorption%20of%20the%20hormone.
12 Migala, J. (2023, November 16). 10 common food and medication interactions to avoid. EverydayHealth.com. https://www.everydayhealth.com/diet-nutrition/common-food-and-medication-interactions-to-avoid/
13 Tosh , P. K. (2022, March 19). Can I drink alcohol while taking antibiotics?. Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/consumer-health/expert-answers/antibiotics-and-alcohol/faq-20057946
14 Mergenhagen, K. A., Wattengel, B. A., Skelly, M. K., Clark, C. M., & Russo, T. A. (2020). Fact versus Fiction: a Review of the Evidence behind Alcohol and Antibiotic Interactions. Antimicrobial agents and chemotherapy, 64(3), e02167-19. https://doi.org/10.1128/AAC.02167-19
15 Bennett, C. (2021, November 17). Does what you eat affect antibiotic effectiveness?. News Medical and Life Sciences. https://www.news-medical.net/health/Does-What-You-Eat-Affect-Antibiotic-Effectiveness.aspx
16 Bennett, C. (2021, November 17). Does what you eat affect antibiotic effectiveness?. News Medical and Life Sciences. https://www.news-medical.net/health/Does-What-You-Eat-Affect-Antibiotic-Effectiveness.aspx
17 Mayo Foundation for Medical Education and Research. (n.d.). Antibiotic-associated diarrhea. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/antibiotic-associated-diarrhea/symptoms-causes/syc-20352231
18 Microbiology Society (2022, November 16). Take probiotics alongside your prescribed antibiotics to reduce damage to your gut microbiome, says the first review of the Data. Microbiology Society. https://microbiologysociety.org/news/press-releases/take-probiotics-alongside-antibiotics-says-first-review.html
19 Ruscio, M. (2024, January 2). The truth about taking probiotics and antibiotics together. Dr. Michael Ruscio, DC. https://drruscio.com/taking-probiotics-with-antibiotics/
20 Ruscio, M. (2024, January 2). The truth about taking probiotics and antibiotics together. Dr. Michael Ruscio, DC. https://drruscio.com/taking-probiotics-with-antibiotics/
21 Rush Memorial Hospital . (2022, January 26). Probiotics and prebiotics should follow antibiotics - rush memorial hospital. Rush Memorial Hospital . https://www.rushmemorial.com/probiotics-vs-antibiotics/#:~:text=Prebiotics%20Boost%20Gut%20Health,good%20microorganisms%20in%20our%20gut.
22 Rush Memorial Hospital . (2022, January 26). Probiotics and prebiotics should follow antibiotics - rush memorial hospital. Rush Memorial Hospital . https://www.rushmemorial.com/probiotics-vs-antibiotics/#:~:text=Prebiotics%20Boost%20Gut%20Health,good%20microorganisms%20in%20our%20gut.
23 Calder P. C. (2022). Foods to deliver immune-supporting nutrients. Current opinion in food science, 43, 136–145. https://doi.org/10.1016/j.cofs.2021.12.006
24 Calder P. C. (2022). Foods to deliver immune-supporting nutrients. Current opinion in food science, 43, 136–145. https://doi.org/10.1016/j.cofs.2021.12.006
25 Burgess, L. (2018, July 10). 15 foods to boost the immune system. Medical News Today. https://www.medicalnewstoday.com/articles/322412#other-ways-to-boost-the-immune-system
Photo by Nataliya Vaitkevich: https://www.pexels.com/photo/sliced-lemon-on-cork-tray-7615467/
