This article was originally published in Thyroid UK Harmony magazine’s September 2021 magazine

Our thyroid health and the mineral zinc are so inextricably linked that for those with an underactive thyroid it’s essential that we look at how much we’re consuming and whether we are getting enough. 

Zinc and thyroid function

Zinc is needed for the T3 thyroid hormone receptors (in our cells) to be active.  So a zinc deficiency will reduce thyroid hormone’s action meaning we are more likely to get hypothyroid symptoms.  Zinc is an important regulator of thyroid hormone. It’s involved in the making of thyroid hormone and it has influence over blood levels of T3, T4 and TSH.

Could hypothyroidism be making you zinc deficient?

It’s likely that zinc absorption is impaired when someone has hypothyroidism.  This has been shown in animals studies and it would make sense that this happens where there is reduced digestive activity (which is often the case in hypothyroidism).

So are you deficient because of hypothyroidism, or are your hypothyroidism and its symptoms down to a zinc deficiency?

Whatever the case, we need to make sure we’re getting enough through food, and that it’s getting absorbed.

How do we test zinc levels in the body?

Blood tests aren’t a reliable way of testing zinc but hair mineral testing can be helpful.  My favourite way is to use a zinc taste test (Lamberts do one called ‘Zincatest).  It’s not an exact science but it gives a good guide that can be repeated easily.

How can we get more zinc?

Seeds, in particular pumpkin seeds, are a brilliant way to get more zinc. You can sprinkle them on salads, muesli, porridge, in stir fries, put them in yoghurt, or make up a trail mix with some other nuts and seeds and have as a high protein snack.

Beef and lamb are the top animal sources – far greater than chicken. Oysters and prawns are the top seafood options.

Chickpeas and lentils have good levels and vegetables-wise, spinach and asparagus are in the lead.  However, these foods (and the seeds) have nutrient inhibitors in them so the animal sources are more ‘bioavailable’ and ready for the body to use.

There is a vast range of foods that contain zinc (although in lower levels) so always eating a broad mix of non processed foods will also get your levels into a good range.

It’s worth mentioning that if there is imperfect gut health, then perhaps not enough zinc will be absorbed in digestion. If you have digestive symptoms like IBS, bloating, constipation or diarrhoea, you may need to work on this.  It’s worth testing zinc levels and if it’s consistently low, then you could seek a practitioner’s advice for ways to help with absorption and promote better digestion.

And you can of course, take a supplement although it’s unadvisable to take one long term as it can disrupt the body’s zinc copper ratio. Supplements usually come in 15 or 30mg doses.

What else do we need zinc for?

As with thyroid health, zinc’s functions go far and wide in the rest of the body. Immunity, reproduction, skin health and vision are some of the crucial areas. 

If you aren’t eating enough zinc rich foods, your immune system can be affected quickly.  Taking a zinc supplement has been shown in studies to reduce the duration of the common cold and to reduce the number of colds suffered when taken for a longer period (

Zinc deficiencies can be associated with acne, hair loss, poor immunity, depression, dermatitis, low sperm count, poor vision, poor concentration and memory and slow healing of wounds (amongst other things).

What to do if you think you might be low in zinc

  • Look at the zinc-rich foods above (and google for more) and assess your intake.  Are you eating them on a daily basis?
  • Consider taking a hair mineral test or a taste test
  • Increase zinc-rich foods as necessary
  • Re-test and if still low, take a supplement for a couple of months and re-test

Article and study references:

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