Q: I have been self-medicating with St. John’s wort for several months to deal with mild seasonal depression and job-hunting stress. I’d rather use this herb because insurance companies penalize you big-time if there is any evidence of treatment for depression. I found this out the hard way, because I am buying my own health insurance policy until I become employed again.

The St. John’s wort seems to be helping. I take it morning and evening. I also take Zocor at bedtime. Is there any interaction between St. John’s wort and my cholesterol-lowering drug? If so, should I not be taking the herb at all, or should I take it at a different time to have less of an effect on Zocor? My pharmacist and I await your wisdom.

A: St. John’s wort lowers the blood levels of Zocor. This might reduce its effectiveness.

You might not have to give up on cholesterol-lowering drugs, however. Pravachol is a similar medication and is not affected by St. John’s wort.

We are sending your “Guide to St. John’s Wort,” “Guide to Heart Health” and “Guide to Cholesterol-lowering Drugs” for more information on interactions and alternatives for lowering cholesterol. Others who would like copies should send $3 in check or money order with a long (No. 10), stamped (57 cents), self-addressed envelope to: Graedons’ People’s Pharmacy, No. CLV-275, P.O. Box 52027, Durham, NC 27717-2027.

It is not likely that taking St. John’s wort at a different time will eliminate the interaction. Grapefruit, for example, affects Zocor and similar drugs for more than 24 hours.

Q: You recently wrote about a potion consisting of vinegar, apple juice and grape juice for the purpose of lowering cholesterol. Vinegar is very acidic. The fruit juices also contain enough sugar to promote decay. As a dentist, I am concerned that this regimen will destroy teeth.

Forty years ago, cheerleaders soothed their abused vocal cords by sucking on lemons. The teeth, especially the front teeth, were often severely damaged. I treated a couple of such cases. This example shows why I feel the vinegar/juice mixture has the potential to cause serious harm.

A: We appreciate your concern. To reduce the risk of damaging teeth, people using this remedy should either drink it through a straw or brush and rinse teeth afterward.

Q: My 3-year-old has turned into a very picky eater. About the only things she likes are pizza, pasta and dessert. I worry she isn’t getting enough vitamins, but my husband says she should get her nutrients from food. I say a multivitamin makes sense. What’s your opinion?

A: We agree with you. A pediatric multivitamin can supply important nutrients, and you won’t have to worry about nagging about vegetables. We think teen-agers might also benefit from multivitamins, as their dietary habits might not be much better than those of your picky eater.

There is one word of caution, however: Do not leave vitamins where your child can reach them. Pediatric vitamins are often flavored like candy, and an overdose can cause poisoning.