Keeping your thyroid healthy comes down to getting the right nutrients, staying physically active, managing stress, and avoiding environmental chemicals that interfere with thyroid function. Most people with a balanced diet and moderate lifestyle habits will never develop a thyroid problem, but a few targeted choices can make a meaningful difference.
Get Enough Iodine, but Not Too Much
Iodine is an essential building block of thyroid hormones. Your thyroid gland pulls iodine from your bloodstream and uses it to produce two key hormones that regulate metabolism, energy, and body temperature. Without enough iodine, your thyroid can’t do its job. Adults need 150 micrograms per day, which most people in developed countries get from iodized salt, dairy products, seafood, and eggs.
The more surprising risk is getting too much. Long-term iodine intake above 1,100 micrograms per day can actually cause thyroid problems, including an underactive thyroid and goiter (an enlarged thyroid gland). The American Thyroid Association advises against taking iodine or kelp supplements containing 500 micrograms or more per day. If you eat a varied diet and use iodized salt, you almost certainly don’t need an iodine supplement. Adding one on top of an already sufficient diet can push you into excess territory and do more harm than good.
Selenium: One to Two Brazil Nuts Is Plenty
Selenium supports the enzymes your body uses to convert thyroid hormones into their active form. It also helps protect thyroid tissue from oxidative damage. The easiest dietary source is Brazil nuts, but they’re unusually concentrated: a single nut contains 68 to 91 micrograms of selenium, and the tolerable upper limit for adults is 400 micrograms per day. Eating a handful daily could push you toward selenium toxicity, which causes brittle nails, hair loss, and gastrointestinal problems. One or two Brazil nuts a day is genuinely enough. Other good sources include fish, shellfish, turkey, and eggs.
Exercise at a Moderate Level
A large Korean population study published in the Journal of Clinical Endocrinology & Metabolism found that moderate physical activity was associated with healthier thyroid hormone levels. People who exercised moderately had higher levels of free T4 (the main hormone your thyroid produces) and lower TSH, which together suggest the thyroid is working more efficiently. The association was particularly strong in women.
Interestingly, neither low nor high physical activity showed the same benefit. The moderate-activity group also had significantly lower levels of thyroid antibodies, markers that indicate the immune system is attacking thyroid tissue. This suggests regular, moderate exercise may help protect against autoimmune thyroid conditions like Hashimoto’s disease. You don’t need intense training. Walking, cycling, swimming, or yoga several times a week fits the pattern that showed benefit.
Manage Chronic Stress
When you’re chronically stressed, your body produces elevated levels of cortisol. Sustained high cortisol can interfere with the conversion of T4 (the storage form of thyroid hormone) into T3 (the active form your cells actually use). The result is that your thyroid may be producing hormones normally, but your body isn’t activating them efficiently. You can feel fatigued, foggy, and sluggish even with “normal” thyroid lab results.
Stress management isn’t a vague wellness suggestion here. It has a direct biochemical link to thyroid function. Sleep, physical activity, and whatever genuinely reduces your stress level (not just what looks good on a checklist) all help keep cortisol in a range where thyroid hormone conversion works properly.
Watch for Environmental Thyroid Disruptors
Certain chemicals in the environment can interfere with your thyroid’s ability to absorb iodine. Perchlorate, found in some drinking water and food packaging, is one of the better-studied examples. At high enough doses, it blocks iodine uptake into the thyroid gland, which can reduce hormone production. In fact, perchlorate has been used as a drug to deliberately suppress thyroid function in people with overactive thyroids.
You can reduce your exposure by using a water filter that removes perchlorate, avoiding microwaving food in plastic containers, and choosing fresh foods over heavily processed or packaged ones. Other common thyroid disruptors include certain flame retardants in furniture and electronics, as well as compounds found in nonstick cookware. Minimizing contact with these chemicals won’t guarantee thyroid health, but it removes one controllable risk factor.
Cruciferous Vegetables Are Fine for Most People
Broccoli, kale, cauliflower, and Brussels sprouts contain compounds called goitrogens that can theoretically interfere with thyroid function. This has led to persistent concern about whether eating these vegetables raw is risky. The clinical consensus is straightforward: goitrogen-containing foods are safe for healthy people. Cooking reduces goitrogen content further. If you already have a diagnosed thyroid condition, it’s worth discussing large quantities of raw cruciferous vegetables with your doctor, but for everyone else, eat them freely. The nutritional benefits far outweigh the theoretical risk.
Gluten-Free Diets and Thyroid Autoimmunity
There’s growing interest in whether a gluten-free diet can help people with Hashimoto’s disease, the most common cause of hypothyroidism. The evidence is early but worth knowing about. In women with autoimmune thyroid disease who hadn’t yet started medication, following a gluten-free diet for 12 months reduced thyroid antibody levels by about 24% compared to increases in women eating a regular diet. TSH levels also dropped from 2.4 to 1.4 in the gluten-free group, suggesting improved thyroid function.
However, the American Academy of Family Physicians notes there is currently no evidence that a gluten-free diet reduces the actual symptoms of autoimmune thyroid disease. The antibody and hormone changes are promising in lab values, but people didn’t consistently feel better. If you have Hashimoto’s and are curious, a trial period is reasonable, but it’s not a proven treatment and shouldn’t replace standard care.
Know Your Numbers
TSH (thyroid-stimulating hormone) is the standard screening test for thyroid function. Most labs define the “normal” reference range broadly, using statistical cutoffs from the general population. But a 2023 study looking at cardiovascular risk found that the optimal healthy range for TSH is narrower than the standard reference range, sitting between roughly 1.9 and 2.9 mIU/L. Values within the normal lab range but outside this optimal window were associated with slightly higher cardiovascular risk.
This doesn’t mean you should panic if your TSH is 1.2 or 3.5. But if you’re proactively monitoring your thyroid, it’s useful to know that “normal” on a lab report and “optimal” aren’t always the same thing. Ask for your actual number rather than just accepting “your results are normal.” Tracking your values over time gives you and your doctor a much clearer picture than any single test.