Q: Recently, I was given a booklet that said because I have thyroid disease, I should watch my diet. The idea is to avoid soy products along with broccoli, cabbage, Brussels sprouts, etc. Can you tell me why?

Also, why must Synthroid be taken on an empty stomach? I have taken it for 35 years, always with food. Now I take it first thing upon awakening. Are there any other interactions I should be aware of?

A: Soy and cabbage family vegetables like those you named have a reputation for causing goiters. This is an enlargement of the thyroid gland often associated with inadequate thyroid hormone. A recent systematic review of 123 studies, however, cast doubt on these vegetables causing problems if the diet has adequate iodine (International Journal of Molecular Sciences, April 3, 2024).

Synthroid should be taken on an empty stomach, since beverages like coffee and tea can interfere with absorption (Frontiers in Endocrinology, Sept. 12, 2022).

Q: I have read that using cactus leaves (nopalitos here in Texas) can help control blood sugar. Since I have diabetes, I decided to try this approach. My doctor agreed to the experiment.

I write down each food I eat and measure my blood sugar every morning. I blend one bag of cactus leaves with 3 1/2 cups of apple juice and drink 4 ounces three times a day. Between January and March, I was not drinking any cactus juice. My morning blood sugar ran between 145 and 160. Once I started the juice, my morning blood sugar started running between 125 and 135. I also found that my triglycerides dropped from 191 to 139 and my cholesterol from 202 to 169.

A: Thank you for sharing your experiment. Nopal cactus pads (Opuntia) have been shown to help control blood glucose and symptoms of diabetes in animal experiments (Journal of Ethnopharmacology, Aug. 10, 2023). Some research suggests that humans may also benefit.

You may want to blend your cactus with a beverage that has less sugar than apple juice.

Q: You wrote recently about MAO inhibitors as antidepressants. I hope they become more widely available. No other antidepressant has worked for me for 25 years. I’ve tried most of the commonly prescribed meds.

You have to watch your diet with MAOIs. I eat an avocado every day and frequently have cheese. I experienced a multiday headache from soy sauce, but I would get migraines from MSG and chocolate even prior to MAOIs.

Two doctors have prescribed meds that don’t mix well with Parnate — a urologist (doxazosin) and a pain doctor (duloxetine). Since they enter all my meds into a program, I wonder why it’s not flagged. It’s important for the patient to be vigilant to avoid food and drug interactions.

A: The monoamine oxidase inhibitors, or MAOIs, were the first antidepressants to be developed. They were discovered accidentally when the tuberculosis drug, isoniazid, was found to lift the mood of patients suffering from TB.

Antidepressants such as isocarboxazid (Marplan), phenelzine (Nardil) and tranylcypromine (Parnate) were approved by the Food and Drug Administration in the late 1950s and early 1960s. In 2006, the FDA approved a transdermal patch containing the MAOI selegiline (Emsam).

People who have not responded to other antidepressants may benefit from treatment with an MAOI-type medicine (Journal of Affective Disorders, May 1, 2025). This will require careful supervision by a physician familiar with such drugs.

In their column, Joe and Teresa Graedon answer letters from readers. Send questions to them via www.peoplespharmacy.com.