Supplements in our foods can interfere with medications

November 03, 2017

Inform your shoppers on some popular supplement-medication interactions.

The popularity of “exotic” vitamin supplements, boosters, enzymes and herbs, previously only found in health food shops and juice bars is increasing, and these “wonder ingredients” are more frequently found in our everyday foods. 

In addition, more and more Americans are taking medications for heart disease, diabetes, cancers, obesity and depression, while supplementing, juicing and consuming meal replacement bars, thus a greater potential for adverse interactions.

Shoppers may assume that manufacturers, retailers, servers, and even baristas understand exactly what these combinations will (and will not) accomplish for our health. This assumption is dangerous, and it is especially important for those consumers with medical conditions or who are taking medications to do their research. And why after years of popularity is the FDA still deferring the responsibility of providing specific information about these ingredient and possible interactions? We know very well that this lack of disclosure may mean trouble.

All retailers who sell nutritional supplements, or the products that contain them, should provide a complete list of ingredients and precautions in each store. Quality training of employees who “dispense” these products is necessary; and at the same time, employees should be cautioned not to “play doctor or nutritionist and diagnose” customers conditions or imply that a dietary supplement will be a cure or replace conventional medical therapy. 

To help get you up to speed on some supplement-medication interactions your shoppers should be aware of: 

  • Calcium and heart medication, thiazide-type diuretics, and aluminum and magnesium-containing antacids- calcium can negate or cause adverse effects.
  • Magnesium and thiazide/ loop diuretics, some cancer drugs, and magnesium-containing antacids.
  • Vitamin K and blood thinners (vitamin K rich foods should also be avoided when taking blood thinners)
  • St. John's Wort and birth control pills - compromises effect of birth control pills. Those prescribed antipsychotic drugs should not take St. John’s Wort.
  • Ginseng and anti-depressant drugs - this combination has been associated with insomnia and headaches. Ginseng also lessens the effects of antipsychotic drugs.

We at can not stress enough the fact that anyone currently taking prescription drugs, should not begin taking supplements until they have consulted their health care provider. Remind your shoppers to always read ingredient labels carefully and always check for food or drug interactions.

An excellent source of information can be your store's pharmacist, who has a complete resource of drug and supplement interactions available. Websites like those of the FDA,, USDA Center for Food Safety and Applied Nutrition,, National Institutes of Health,, and resource guides like The Natural Pharmacy and Encyclopedia of Nutritional Supplements are also good sources for more information. Another good source is the Vitamin and Herb University