If I add one drop of tinture of iodine to my food weekly, is there a downside?

How do you know your "low salt" diet does not supply enough iodine? Are you using iodized salt in minimal quantities? Does your caregiver order periodic tests of you thyroid function to assess your iodine uptake requirements? If so, is an iodine supplement indicated? Tincture of iodine is recommended for external use only in the disinfection of minor wounds, and as an emergency disinfectant for drinking water in the field. It is not recommended for internal consumption or as a dietary supplement.

First of all, tincture of iodine is not for internal use. Secondly, one drop is a homeopathic dose. (Homeopathic = worthless)

If you feel you need iodine supplementation, discuss it with your doctor. The cheapest oral form of iodine is SSKI, saturated solution of potassium iodide.

Try adding kelp flakes to your diet, they are a good source of iodine from food.