Jury’s out on whether soy products may affect thyroid
Q: I really like the flavor of soy milk, but I’ve found that drinking it interferes with my thyroid treatment. I’ve been taking the same dose of Armour thyroid for more than a decade. After I started drinking a couple of glasses of soy milk every day, I noticed symptoms of hypothyroidism. I would feel cold and not be able to warm up.
Once I stopped the soy milk, my hypothyroid symptoms went away. Now I stay away from all soy. I think I could tolerate small amounts here and there, but not a lot every day. I make sure to take my thyroid medicine separately from any food intake.
When I mentioned this to my doctor, she gave me the side eye. How wellknown is this interaction? A: It sounds as if you have done your own N of 1 experiment to determine how soy products affect your thyroid function. There are relatively few randomized controlled trials addressing a potential interaction.
Back in 2002, scientists found that certain natural compounds in soy called isoflavones can inactivate an enzyme crucial for thyroid hormone regulation (Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences, Sep. 25, 2002). This led some researchers to suspect that soy isoflavones might interfere with thyroid function (Environmental Health Perspectives, June 2002).
A few case studies have confirmed that some individuals react as you do
(Endocrinology, Diabetes & Metabolism Case Reports, July 19, 2021). A meta-analysis revealed some contradictory findings (Scientific Reports, March 8, 2019).
Soy is not the only food that might affect thyroid hormones, however. You are smart to take your medicine away from mealtime, since coffee, tea and supplements containing iron or calcium can reduce absorption.
Q: I had COVID-19 a few months ago. My doctor prescribed Paxlovid. I was on four kinds of blood pressure medications twice daily. Paxlovid interacted with my pills. As a consequence, my blood pressure dropped so low that I was not able to take three of them. I stuck with just half of my regular beta blocker. Has anyone else had this problem? A:
No one should ever take this antiviral medicine without having the prescriber and the pharmacist double check on potential drug interactions. Your experience is not unusual because so many
medications can interact with this COVID-19 drug.
Q: About 15 years ago, I saw an orthopedic surgeon about pain in my left knee. He said the cartilage was worn and offered no solution except to avoid stairs and certain pieces of equipment at the gym. About that time, I read in the People’s Pharmacy about glucosamine sulfate and thought,“That can’t hurt.” I started taking 500 milligrams twice a day. Within two weeks, the pain was gone and has been gone ever since. I highly recommend trying it. A:
Thank you for your recommendation. A review of 18 randomized controlled trials shows that glucosamine sulfate is better than placebo for alleviating knee pain due to osteoarthritis (Clinical Rheumatology, September 2018). Many other readers agree that this approach can be helpful.