Health Education

How Diet and Supplements Can Interact with Medications

Cropped SingleCare logo By | June 6, 2017

Dietary supplements are growing in popularity while simultaneously becoming readily available at most stores and pharmacies. As a matter of fact, the dietary supplement market is expected to grow to a whopping $278 billion by the year 2024. Most often, people don’t think twice about taking a supplement given the fact that they are generally natural substances and portrayed as harmless. It is estimated that nearly 68% of Americans use a dietary supplement and that 84% of Americans express confidence in the safety, quality, and effectiveness of the supplements that they take.

Surprisingly, dietary supplements and certain foods have the potential to drastically impact prescription medications. The Food and Drug Administration regulates dietary supplements but in a much less stringent manner compared to over the counter or prescription medications. This reality, coupled with the fact the few dietary supplements and foods have been tested to see how they interact with prescription medications leaves a lot of effects unknown to healthcare providers and pharmacists alike.

Foods that interact with medications

Foods that have a high density of certain elements can counteract or change the effectiveness of prescription medications. If you eat a significant amount of a particular food and take a particular class of medication, you could be at risk for adverse effects. Here are a few examples.

  1. Green leafy vegetables: Vegetables such as broccoli, cabbage, spinach, kale, and brussel sprouts all contain a high amount of vitamin K. Vitamin K plays a key role in helping blood to clot, thus preventing excessive bleeding. It is actually used to counteract a common medication called Coumadin (also called Warfarin). Therefore eating green leafy vegetables could be working against and hindering the intended purpose of Coumadin. Other supplements such as garlic, ginger, ginseng, and ginkgo can do the opposite of vitamin k and increase the chances of bleeding.
  2. Grapefruit juice: Grapefruit can alter the effectiveness of certain medications. A particular element call furanocoumarins can alter the characteristics in medications. You should avoid grapefruit juice while taking statin medication such as Simvastatin (Zocor), blood pressure medications, antihistamines, or even birth control.
  3. Tyramine: This substance is naturally found in food such as smoked fish, aged cheese, and cured meats. A certain class of depression medication labeled MAOI can break down tyramine levels which are used to help the body regulate blood pressure.
  4. Salt Substitutes: People taking digoxin or ACE inhibitors should be wary of salt subsititues, as most replace sodium with potassium. Those taking ACE inhibitors may see a significant increase in potassium.
  5. Alcohol: Although not considered to be a food, alcohol can be harmful if taken with most medications. Mixing alcohol with medications and lead to intensified side effects such as nausea/vomiting, headaches, fainting, or loss of coordination. Alcohol has been known to make medications less effective or possibly toxic to the human body.

Supplements could also cause interactions

There are about 5,300 distinct dietary supplements, most of which have not been studied systematically. Studies have found that a number of supplements may affect the way certain enzymes in the body metabolize drugs. They may inhibit the enzymes’ ability to break down a drug, causing medication to build up to potentially toxic levels. Others may increase the rate at which a drug is broken down, making it less effective. More than half of patients with chronic disease or cancer user dietary supplements with prescription medications. Generally speaking, small quantities are safe, but concentrated in pills and taken in long periods of time, these supplements could have adverse effects.

  1. St. John’s Wort: Intended for relieving depression and fatigue, it may reduce the effectiveness of contraceptives, HIV/AIDS drugs, and anti-rejection drugs. Combining St John’s Wort with OTC cough medicines or antidepressants could cause serotonin syndrome, which is a dangerous condition that can cause rapid blood pressure changes. It can reduce the levels of anti-rejection drugs in organ transplant patients by 70%.
  2. The Four G’s (Ginger, Garlic, Ginseng, and Ginkgo) – these four popular supplements can interact with a variety of medications, such as increasing the risk of bleeding in patients on blood thinners. If patients are undergoing surgery, doctors advise stopping use of the supplements at least a week or two before.
  3. Magnesium: Supposedly aiding migraines, heart disease, and fatigue, magnesium supplements may reduce absorption of antibiotics and increase absorption of blood thinners.

Tips on how to be safe

  • Knowing your diet well. Generally speaking, interactions will only occur in with the ingestion of high doses of supplements whether in pill form or through your diet. Knowing what foods you eat will help you to determine what supplements you might be getting high doses of.
  • Speak with your doctor or pharmacist. When starting a medication it is best to do some research on it. Ask your doctor if there are any dietary concerns with a medication you are on. Also, the National Center for Complementary and Alternative Medicine has useful information about many commonly used supplements.
  • Read medication labels. Medication labels will tell you what foods or other things to avoid. Like we mentioned above, alcohol can lead to many adverse medication reactions. Medications generally have warning labels that you should be sure to take note of.
  • Keep your doctor up to date. Make sure you tell your doctor or pharmacist before starting any new supplement or drastically changing your diet. Since supplements can be purchased online or in person without a prescription it is easy to start a supplement without informing your doctor. Make sure you add the supplements you take to your medication list that is in your medical record. Vanessa Grubbs, M.D., a kidney expert at San Francisco General hospital, found that 6.5 percent of kidney patients were taking a supplement that contained one or more of the 39 herbs considered to be dangerous for people with kidney problems.
  • Be careful where you buy supplements. Generally, it is safe to buy medications in the U.S. Problem is that when purchasing online you could be buying supplements from around the world. It can be risky to buy supplements from other countries as the safety and effectiveness of those medications have not been reviewed by the FDA.

Eating a healthy diet and taking supplements can be a key component to a healthy lifestyle. Consult your doctor about any supplements you take or consider taking. When starting a new medication, ask your pharmacist what known dietary risks you should be aware of, if any. Knowing your diet and having some intentional conversations will help to ensure your medications are serving their intended purpose.