By James Wood
Published: 12 May 2025

When it comes to strong, healthy hair, most of us instinctively reach for better shampoos, conditioners, or hair oils. But the truth is, beautiful hair begins with what’s happening inside the body. Two internal systems that are often overlooked in hair care are thyroid function and iron absorption. These powerful physiological processes play a vital role in maintaining vibrant hair health.

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Thyroid Function and Hair

Thyroid hormones regulate metabolism, including the activity of hair follicles. Disruptions in thyroid function can have a significant impact on hair condition:
        •       Underactive thyroid (hypothyroidism) is commonly linked to thinning hair, dryness, and slowed growth.
        •       Overactive thyroid (hyperthyroidism) can lead to excessive shedding. This is because a thyroid imbalance may push hair prematurely out of its growth phase (anagen), causing it to fall out sooner than it should and leading to noticeable hair loss.

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Iron and Hair Health

Iron plays a crucial role in transporting oxygen to cells—including those within the hair follicles. This oxygen delivery is essential for cellular energy and growth. Even low levels of ferritin (a protein that stores iron) can result in a form of hair loss known as telogen effluvium, which involves diffuse shedding across the scalp and a general thinning of hair.

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The Thyroid–Iron Connection

Interestingly, thyroid function and iron status are deeply interconnected:
        •       Low thyroid activity can reduce stomach acid production, making iron absorption less efficient.
        •       Autoimmune thyroid conditions may elevate systemic inflammation, which increases levels of hepcidin, a hormone that traps iron in storage and reduces its availability for essential functions like hair growth.

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What You Can Do
        1.      Ask your GP for a comprehensive blood test that includes thyroid panels, ferritin, and iron saturation levels.
        2.      Incorporate iron-rich foods into your diet, and pair them with vitamin C, which enhances iron absorption.
        3.      Support both gut and thyroid health by considering nutrients such as selenium, magnesium, vitamin B12, and adaptogens like ashwagandha, as well as probiotic and prebiotic foods.
        4.      Choose high-quality supplements when needed. (I personally use Nutrigold UK as a trusted brand.) For iron, opt for bioavailable forms such as iron bisglycinate. For B vitamins, methylated forms are generally better absorbed.

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Conclusion

Hair changes are often a sign of something deeper occurring within the body. Addressing your thyroid function and iron metabolism may be the missing link to stronger, fuller hair—and improved overall well-being.