People’s Pharmacy | Too much zinc disrupted liver enzyme

Q. A few weeks ago, you answered a question about zinc supplements. You warned that taking zinc long-term might result in nerve pain and raise alkaline phosphatase levels. I had high levels for years, and my doctors thought I might have problems with my liver or bones, though they could not find anything. I even had a bone scan.

I had been eating Raisin Bran each morning and frequently consumed nuts. In addition, I took PreserVision AREDS 2 daily as well as a multivitamin that contains zinc. I would also take zinc lozenges to ward off colds. When I read about the connection between zinc and alkaline phosphatase, I changed my breakfast cereal, stopped the multivitamin and zinc for colds and gave up eating nuts.

I am still taking PreserVision AREDS 2, as I have early macular degeneration and my ophthalmologist recommends it. Three months later, a blood test showed my alkaline phosphatase was normal. They are still normal after three years now. I had undergone a number of tests and quite a bit of worry because of the zinc.

A. Your story is a great reminder that minerals like zinc don’t just appear in dedicated pills or lozenges, but also in food. Since your alkaline phosphatase is now normal, you seem to have found a path that is working. The recommended intake (RDA) of zinc is 11 mg for men and 8 to 12 mg for women. (The higher amount is for women who are breastfeeding.) The tolerable upper intake level has been set at 40 mg/day.

Oysters are an exceptionally rich source, with around 30 mg per serving. That is roughly ten times more than other good sources such as beef, fortified breakfast cereal or pumpkin seeds. We have long worried about the high dose of zinc (80 mg) in the AREDS formula. It does contain 2 mg copper to help offset the danger of an imbalance.

Part of the AREDS 2 study tested 25 mg of zinc with the rest of the supplement ingredients and found it equally effective (JAMA, May 15, 2013). But because the number of participants in that arm of the study was low, they did not provide a clinical recommendation. If scientists conduct a well-controlled follow-up study, perhaps they will set zinc at the lower dose.

Q. A few months ago, you wrote about antiviral medicines. Flu season is over now, thank goodness, but there are still some viral illnesses around. There are probably effective antiviral herbs already in your yard.

Sage, thyme and oregano fight viral sickness, and garlic and ginger are probably already in your kitchen. Use them! I make glycerites out of sage, thyme, oregano and many other herbs. I hardly ever get sick anymore, and I used to be sick all winter.

A. Thank you for this excellent reminder. Anyone who would like more details on using these and other plant medicines may be interested in our book, Spice Up Your Health: How Everyday Kitchen Herbs & Spices Can Lengthen & Strengthen Your Life. They can find it in the books section of the store at www.PeoplesPharmacy.com.

Q. I listened to your podcast about how to maintain a healthy liver and the expert you were interviewing said that drinking coffee helps. Does it matter if it’s decaf or regular? (Surprisingly, this was not mentioned.)

A. An analysis of UK Biobank participants found that instant, ground and decaffeinated coffee were all associated with less liver fat and iron, markers of liver dysfunction (Molecular Nutrition & Food Research, Dec. 2025). According to this analysis, tea drinkers are less likely to have liver inflammation as well.

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In their column, Joe and Teresa Graedon answer letters from readers. Write to them in care of this newspaper or e-mail them via their Web site: www.PeoplesPharmacy.com. Their newest book is Top Screwups Doctors Make and How to Avoid Them (Crown)

This story was originally published April 29, 2026 at 1:00 AM with the headline "People’s Pharmacy | Too much zinc disrupted liver enzyme."