The food you eat can affect the medication you are taking. You should be aware, for example, that grapefruit can increase the risk of side effects from a wide variety of drugs. The side effects described below can occur from eating grapefruit while on the specified medications.
• Grapefruit can cause flushing, headaches, and increased heart rate if eaten while taking calcium-channel blockers (such as nifedipine, amlodipine, verapamil, and felodipine), which help decrease blood pressure.
• Grapefruit increase quinidine levels.
• Grapefruit can cause irregular heart rhythms if eaten while taking the antihistamine terfenadine.
• Grapefruit can increase levels of benzodiazepines (sedatives that include alprazolam, diazepam, midazolam, and triazolam).
• Grapefruit can cause kidney and lvier toxicity if eaten while taking cyclosporine.
• Grapefruit increases caffeine levels and can cause nervousness and insomnia.
• Grapefruit can decrease the absorption of macrolide antibiotics such as clarithromycin.
• Grapefruit can decrease the absorption of the antihistamine fexofenadine (such as Allegra).
• Grapefruit can increase the medication level of HMG-CoA reductase inhibitors (statin drugs).
• Grapefruit can delay the absorption of Viagra, a male impotence medication.
• Grapefruit can cause hives if taken with the pain reliever naprosyn.
• Grapefruit can increase certain levels, which may lead to nausea, tremors, drowsiness, dizziness, or agitation, if eaten while taking carbamazepine (such as Tegretol).
• Grapefruit may elevate blood levels and cause nausea, drowsiness, tremors, or agitation if eaten while taking amiodarone.
• Grapefruit can increase estrogen levels in both men and women. No interaction with medication is necessary for this to occur.
Combining Vitamins and Minerals
Vitamins and minerals can interact with each other, as well as with other nutrients. These relationships and interrelationships can have various effects. The following examples show how certain vitamins and minerals interact.
• A certain amount of vitamin C is necessary for your body to use selenium effectively.
• Vitamin C can enhance the availability of vitamin A.
• Too much zinc can decrease calcium absorption.
• Vitamin D increases the absorption of calcium and magnesium.
• Vitamin D helps your body use zinc effectively.
• Too much copper can decrease the uptake of manganese in your system.
• A vitamin A deficiency can decrease iron utilization.
• Too much iron can lower your manganese and copper levels.
• Too much vitamin B2 (riboflavin) can cause a magnesium deficiency.
• Vitamin B6 can cause a decrease in copper absorption.
• A vitamin E deficiency can decrease absorption of vitamin A.
• A vitamin B6 (pyridoxine) deficiency can lead to a decreased use of selenium.
• Adequate phosphorus intake is needed to maintain vitamin D.