Two everyday seasonings many people use are “catalysts” for thy.roid can.cer

You should think carefully before using these two seasonings frequently.

Mrs. Wang, a 48-year-old woman from China, found joy after retirement in experimenting with home-cooked dishes. She often said, “Seasonings are the soul of a dish.” Her two “secret weapons” were iodine-rich rock salt and MSG, which she believed made food “so delicious it makes your eyes squint.”

Last month, during a routine health check for retired staff, the ultrasound doctor paused for an unusually long time while examining her neck:
“There is a 2.8 cm nodule in your thyroid. Its shape looks concerning. A biopsy is needed immediately.”

The result came three days later: “Suspicious for papillary thyroid cancer.” When the doctor asked about her dietary habits, he said bluntly:
“The two seasonings you frequently use may be the ‘catalysts’ that triggered your thyroid problems.”

The risk from iodine-rich salt

In the past, iodine-enriched salt was considered a “smart nutrient source” that prevented iodine deficiency in many regions. But today, as people consume more seafood, excessive intake of iodine-enriched salt has become a health risk.

The thyroid needs iodine to produce hormones, but adults only require 150–300 micrograms per day. Long-term excessive iodine intake can trigger the Wolff–Chaikoff effect, in which the thyroid suppresses its own hormone production. This leads to compensatory cell proliferation, formation of thyroid nodules, and eventually, in some cases, can progress to cancer.

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Hidden dangers of MSG

MSG contains monosodium glutamate, a compound that enhances flavor and makes food irresistibly tasty. However, studies published in the Chinese Journal of Endocrinology and Metabolism show that glutamate may affect thyroid follicular cells. When excessive iodine is also present, the harmful effects can be amplified.

A five-year study involving 5,000 participants found that those who consumed more than 5 grams of MSG per day had a 31% higher rate of thyroid dysfunction compared to those who consumed less.

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Long-term consequences

• Thyroid dysfunction:
  Thyroid hormones regulate the body’s entire metabolism. When thyroid function declines, the body becomes fatigued, even after sufficient sleep. Unexplained weight gain—especially around the abdomen and thighs—may also occur.

• Increased risk of thyroid nodules:
  Thyroid nodules are localized overgrowths of thyroid cells. While 85–90% are benign, 10–15% may become cancerous. Older adults who consume both iodine-rich salt and MSG have a 40% higher detection rate of nodules compared to those with a balanced diet.

• Immune system disorders:
  The thyroid is closely linked to the immune system. Overuse of these seasonings may disrupt immune function and lead to autoimmune thyroiditis (Hashimoto’s disease), which slowly destroys thyroid cells.

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How to reduce the risk

• Gradually reduce seasoning intake:
  Your taste buds adapt quickly—just 2–4 weeks. Use the “step-down method”: reduce by 1/4 in the first week, 1/2 in the second week, and after one month, use only 1/3 of your original amount.

• Use better cooking techniques:
  Add salt near the end of cooking to retain flavor while using less. Use non-stick pans to reduce oil and limit seasoning.

• Read food labels carefully:
  Salt and seasonings are hidden in many products. MSG may appear under names like “monosodium glutamate,” “hydrolyzed vegetable protein,” “yeast extract,” or “flavor protein.”
  Iodine can hide in “sea salt” or “seaweed extract.” Always check labels before buying.

• Regular thyroid check-ups:
  People over 40 should have a thyroid ultrasound annually. Those with a family history of thyroid disease should begin screening from age 30.

• Self-check at home:
  Once a month, stand in front of a mirror, tilt your head back, and check for lumps in the neck. Swallow and observe any movement. Use your fingers to gently feel both sides of the windpipe for hardness or pain.