Grapefruit-Medication Interactions

Q: I heard grapefruit interacts with certain medications. Is this true?

A: Yes. Unlike other citrus fruits, grapefruit interferes with the metabolism of a few dozen drugs (see partial list below). A chemical component within the fruit prohibits a certain digestive enzyme in the body from breaking down these medications. By continuing to consume grapefruit or grapefruit juice, you decrease the efficacy of the medication you’re on, and the drug itself can build up to dangerously high levels in the blood. Grapefruit should be fully avoided, as its effects wear off very slowly and are still evident 24 hours after consumption. Separating medicine and grapefruit by several hours will not prevent the drug-nutrient interaction. Having grapefruit once accidentally, most likely, will do no harm, but it’s advisable to switch to another type of fruit or fruit juice. The National Institutes of Health recommends not making any sudden diet changes, however, if you’ve always taken your medication with grapefruit. Speak to your doctor first, as your body may be accustomed to a certain level of the drug in your blood.

Avoid grapefruit and grapefruit products when taking the following:

• The high blood pressure/angina drugs Plendil and Procardia/Adalat
• The cholesterol-lowering agents Zocor, Lipitor and Mevacor
• The immunosuppressant medications Sandimmune and Rapamune
• The anti-anxiety/anti-insomnia drugs Valium, Halcion and Versed
• The neurological medications BuSpar, Zoloft and Tegretol

Note: This is not a complete list of medications that interact with grapefruit. Always check with your physician and/or pharmacist.

How many supplements do you take?

Q: I take a lot of vitamin and herbal supplements? Is that safe?

A: The sale of nutrient supplements is a billion dollar a year business. But whether you’re looking to ward off cancer, lose weight or make up for poor eating habits, you must be careful when taking supplements! In 1994, the U.S. Food & Drug Administration revised government regulation of dietary supplements, which include vitamins, minerals, amino acids, herbs, enzymes and many other substances. The new law determined that it is up to the manufacturer of the supplement to make sure that the product is safe, the label claims are substantiated by solid evidence and that the supplement’s content matches ingredients declared on the packaging. In short, supplements do not need approval from the FDA prior to marketing, nor does the FDA analyze the composition of these products. Manufacturers are required to investigate and alert the FDA of any reports of adverse health events associated with the product.

Supplements are indicated for certain groups of people: people with diagnosed nutrient deficiencies, pregnant women, infants, those who are lactose intolerant, perpetual dieters, those addicted to drugs or alcohol, strict vegetarians, and those suffering or recovering from illness, surgery or injury. While these may be valid reasons to be taking supplements, you should always notify your doctor of any over-the-counter products you’re consuming.

Taking supplements increases your risk of toxicities. High potency single nutrient supplements can cause accidental poisoning that can result in liver damage, shock and possible death. High doses can be very dangerous and labels can sometimes lure you with misleading or unproven claims. Certain nutrients, such as the fat-soluble vitamins A, D, E and K, can build up in your system over time. In fact, intakes of vitamin A just twice the recommended amount, taken over a few years, are associated with osteoporosis, while daily supplements of beta-carotene may increase lung cancer risk in smokers.  Always adhere to government-set tolerable upper intake levels, unless your doctor suggests otherwise. (Click here for detailed information on daily recommendations and upper limits for vitamins and minerals, divided by age and gender.)

Supplements can also affect the absorption and metabolism of medicines you take and nutrients in the food you eat. For example, when taken in a pure form, zinc interferes with copper and calcium absorption and calcium hinders magnesium and iron absorption. In addition, the herbal product St. John’s Wort can severely limit the effectiveness of AIDS medications and is not recommended when simultaneously taking an antidepressant from the SSRI family. Clearly, taking multiple over-the-counter supplements increases your chance for harmful food-drug and drug-drug interactions.

My best advice is to try and get all your nutrients from food! Taking a multivitamin can help “cover your bases,” but any amount of certain vitamins or minerals consumed in excess of what your body needs will generally be excreted. While a banana and a tablet may both contain potassium, the fruit provides a balanced assortment of nutrients, fiber and phytochemicals (beneficial, active plant compounds) that can temper the effects of the mineral.

Benefits of Fiber

Q: What exactly is ‘fiber’ and why is it so good for you?

A: Fiber is an indigestible carbohydrate, or a string of sugar units held together by bonds that human digestive enzymes cannot break. There are two types: soluble and insoluble fiber.

Food Sources

Soluble fiber: barley, oats, oat bran, rye, fruits (especially apples and citrus), beans, vegetables, seeds

Insoluble fiber: Brown rice, fruits, beans, seeds, vegetables (cabbage, carrots, brussels sprouts), wheat bran, whole grains

While fiber does not provide energy, it has many other beneficial effects:

1. Lowers blood cholesterol: Soluble fiber reduces cholesterol and the risk of heart disease by several mechanisms. (Note: This is why General Mills is able to claim that eating whole grain oat Cheerios can help lower your cholesterol.)

2. Maintains bowel function: Insoluble fiber speeds up the transit of food through your system, while soluble fiber slows it down.

3. Assists blood glucose control: Soluble fiber slows the absorption of glucose from the intestine into the blood stream, thereby preventing a spike (and crash) in blood glucose after a meal. This can lower the risk of type 2 diabetes.

4. Promotes weight management: Fiber makes you feel full and lessens hunger

5. May defend against colon and rectal cancer: Scientific studies are mixed, but insoluble fiber speeds up the removal of cancer-causing agents from the colon, while resident bacteria in the colon ferment soluble fiber, producing a beneficial compound that may help colon cells resist injury.

Recommended Intake: Since most fiber-rich foods supply a mixture of soluble and insoluble fiber, recommendations are given without regard to type. The American Dietetic Association suggests 20 – 35 grams of fiber daily, which is about twice the average intake. That said, don’t overload on fiber and make sure to increase fluid consumption as you gradually increase fiber intake.

Fruits, vegetables, whole grains and beans are among the best sources of fiber! Also, remember that fiber supplements are not necessarily substitutes for whole, fiber-rich foods.

Check the nutrition facts on the back of products to find out how much fiber is in one serving! Here are some examples:

½ cup whole grain barley – 3g fiber

½ cup instant oatmeal – 2g fiber

1 slice whole wheat bread – 3g fiber

1 slice white bread – 1g fiber

½ cup cooked brown rice – 2g fiber

½ cup cooked white rice – less than 1g fiber

¾ cup (2 oz) whole wheat penne pasta, dry – 6g fiber

¾ cup (2 oz) regular penne pasta, dry – 2g fiber

1 medium apple (with skin) – 3g fiber

1 medium pear (with skin) – 5g fiber

½ cup blackberries – 4g fiber

½ cup strawberries – 2g fiber

1 medium orange – 4g fiber

½ cup orange juice – less than 1g fiber

½ cup American grapes – less than 1g fiber

½ cup lentils – 8g fiber

½ cup chickpeas (garbanzo beans) – 5g fiber

½ cup black beans – 7.5g fiber

½ cup cooked broccoli – 2.5g fiber

1 medium artichoke – 10g fiber

1 medium baked potato (with skin) – 4.5g fiber