What is the best thyroid support supplement for an underactive thyroid?
There are a whole range of thyroid support supplements for you to consider if you have an underactive thyroid. Which ones will optimise your thyroid function will depend to some extent on whether you have Hypothyroidism (an underactive thyroid) or Hashimoto’s Thyroiditis (an auto immune thyroid condition) and also on your diet but here are some key recommendations based on my clinical experience in practise.
Thyroid Support Supplements
Zinc
Zinc is important for thyroid hormone production and conversion and 25mg dosage to help optimum zinc delivery to thyroid gland.
Selenium
Selenium is important mineral for thyroid function because it activates enzyme responsible for conversion of T4 to T3 the active thyroid hormone. Selenium supplementation shown to reduce inflammation with autoimmune thyroiditis. If you are on a low calorie diet this mineral together with Zinc is key in preventing decline of T3. Dosage of no more than 400mcg daily is recommended.
Tyrosine
Tyrosine is a precursor thyroid hormone and low levels make it difficult for thyroid to work properly 85-170mg daily.
Guggul
Guggul is an Ayurvedic thyroid stimulating agent which has the ability to take up enzymes needed for thyroid conversion and prevent sluggish thyroid metabolism.
Omega 3 and Omega 6
These essential fatty acids are critical to thyroid function because they increase energy levels in cells, required for integrity of structure of every membrane of every cell and improve body’s ability to detect and respond to thyroid hormone effectively
Iodine
Iodine is more controversial as whilst it is a cofactor for thyroid function and tolerated in small amounts in a multi, too much can actually aggravate thyroid symptoms so get practitioner to test for iodine deficiency. This may be one where eating sea vegetables and other iodine rich foods like seaweed / sushi or shellfish may be preferable to supplementation.
Ashwagandha
This adaptogenic herb may improve thyroid function by helping to increase T4 levels of thyroid hormone. T4 is the substrate for T3 and T3 thyroid hormone sets your metabolism and energy levels.
Thyroid Glandulars
This would be something to consider alongside your thyroid medication (levothyroxine) if you have an autoimmune thyroid condition or have permanent thyroid damage from radioactive iodine but only after a consultation with a Functional Medicine Practitioner. They contain animal thyroid tissue (usually in form of Bovine) and support the thyroid at a glandular and tissue level.
Important note – if you are taking Prescription medication (usually Levothyroxine) it is important to consult with your GP or a Functional Medicine Practitioner before taking new supplements.
For more information on thyroid support see my previous article on “How to boost Thyroid Function naturally“.

Get in touch
Angela Loftus BSc, PGDip, DipION, CFMP, BANT, CNHC – a fully qualified Nutritional Therapist and Certified Functional Medicine Practitioner based in Chorleywood, Hertfordshire.
If you suspect that you may have an under active thyroid and would like help in diagnosing and improving your situation, don’t hesitate to contact me using the form below. *Please note that my responses can sometimes go into junk folders so be sure to check there.