by Dr Jess Braid

find natural support through dietary supplements 

Vitamins, dietary nutrients and minerals all play a surprisingly big role in how healthy our thyroid is. While the medical profession is still learning about the many and often complex ways in which these nutrients work, we do know which nutrients have shown to be of benefit to those who are experiencing hypothyroidism (low thyroid hormone):

vitamin A

Supplementation with vitamin A for four months has been shown to significantly reduce TSH (Thyroid Stimulating Hormone) levels and increase T3 levels in premenopausal women1. A deficiency in vitamin A can lead to hypothyroidism, particularly affecting the body’s own levels of T3. This deficiency can sometimes be missed in a standard blood testt,2 so we suggest that if you have concerns that your thyroid is not functioning as it should, you add some extra vitamin A to your diet. The RDA (Recommended Daily Amount) of vitamin A is 900-3000μg per day. Sources of vitamin A derived from beta carotene are always safer, as other, active forms of vitamin A can be toxic in higher doses. Vitamin A is a fat-soluble vitamin and therefore cannot be absorbed without fat (so consume a supplement with food).

The top 5 sources of vitamin A:

  • Goji berries – dried (8128μg, per 100g)
  • Liver – beef, pan-fried (5454μg, per 100g)
  • Sweet potatoes (4490μg, per 100g) most as beta-carotene
  •  Spinach – raw (852μg, per 100g) most as beta-carotene
  • Carrots – raw (627μg, per 100g) most as beta-carotene

B vitamins including B2, B6 & B12

B2 (riboflavin) deficiency causes low thyroid hormone levels3. Patients with vitamin B2 deficiency are also significantly more prone to depression.3 The T4 hormone helps vitamin B2 be converted to its more active form, so it can be used by the body.4 A vitamin B2 deficiency can also lead to a vitamin B6 deficiency,5 so a complete B vitamin supplement can be advisable if you are experiencing thyroid issues. The RDA of Vitamin B2 is 1.3-40mg per day and there are plenty of tasty, fresh ways to get extra B2 in your diet. Vitamin B2 can be destroyed by sunlight and easily gets ‘lost’ from food during processing, so we encourage eating a variety of fresh sources of B2 as part of a balanced diet. 

The top 5 sources of vitamin B2:

  • Liver – beef, pan-fried (3mg, per 100g)
  • Eggs –  whole, boiled (0.4mg, per 100g)
  • Portobello mushrooms – grilled (0.4mg, per 100g)
  • Yoghurt or kefir – full fat (0.3mg, per 100g)
  • Beef steak – cooked (0.3mg, per 100g)

B6 (pyroxidine). Animal studies show that low vitamin B6 (pyroxidine) levels can cause a reduction in TSH and therefore low T3 and T4. Its action seems to be on the hypothalamus.6 Low vitamin B6 causes poor immune function, which is important in the main causes of thyroid disease. The RDA of vitamin B6 is 1.4-200mg per day. Women who are taking oral contraceptives can be low in B6, as can those with inflammatory diseases, such as rheumatoid arthritis.

The top 5 sources of vitamin B6:

  • Pistachios – roasted (1.7mg, per 100g)
  • Tuna – yellowfin, cooked (0.9mg, per 100g)
  • Salmon – wild Atlantic (0.8mg)
  • Liver – beef, pan-fried  (0.7mg, per 100g)
  • Chicken or turkey breast – roasted (0.6mg, per 100g)

B12 – Approximately 40% of hypothyroid patients are B12 deficient, yet many don’t have any symptoms of B12 deficiency. Even those with ‘normal’ B12 levels can see an improvement in hypothyroid symptoms from adding B12 supplements.7 The RDA of vitamin B12 is 1.5μg-2000μg per day. 

A B12 deficiency is very common in vegans and non-meat eaters, as vitamin B12 is derived from animal-based foods, so if you are vegetarian or vegan a supplement is always advisable. 

The top 5 sources of vitamin B12:

  • Clams (98.9μg, per 100g)
  • Liver – beef, pan-fried (26μg, per 100g)
  • Sardines – tinned in oil (8.9μg, per 100g)
  • Tuna – tinned in water (4.2μg, per 100g)
  • Beefsteak – grass-fed, minced, cooked (2.6μg, per 100g)

vitamin C

Vitamin C can protect the thyroid from damage by chemical toxins and heavy metals.8,9 The RDA of vitamin C is 60mg-1000mg per day. However, vitamin C is very safe, even at very large doses of up to 10,000mg. Its only side effect is diarrhoea (which can make it useful to relieve constipation). Vitamin C cannot be stored in the body, so must be consumed regularly.

The top 5 sources of vitamin C:

  • Red pepper – sweet, raw (128mg, per 100g)
  • Kiwi fruit (92.7mg, per 100g)
  • Broccoli – cooked (64.9mg, per 100g)
  • Strawberries (58.8mg, per 100g)
  • Oranges (53.2mg, per 100g)

vitamin d

vitamin D

Vitamin Dhelps to maintain a healthy immune system. Our diet rarely gives us enough vitamin D, as it is produced as a result of outdoors exposure to sunlight. When vitamin D levels are low, you are more likely to have autoimmune thyroid disease,10 such as hypothyroidism (Hashimoto’s). In the UK, the low light levels make vitamin D deficiency common. In one study, after taking a vitamin D supplement patients saw a substantial decrease in the levels of antibodies attacking the thyroid gland.11 The recommended daily amount of Vitamin D is 10-100μg per day (400-4000IU). It is important to take a supplement* if you are pregnant, spend a lot of time indoors or have a darker skin colour.

*(If you are over 30, take vitamin K2 alongside any vitamin D supplement, to avoid the potential calcification of blood vessels.)

The top 5 sources of vitamin D:

  • Sunlight – our main source
  • Swordfish – cooked (16.5μg, per 100g)
  • Salmon – sockeye, cooked (13.2μg, per 100g)
  • Tuna – yellowfin, cooked (1.7μg, per 100g)
  • Egg – large, boiled (2.2μg, per 100g)


Iodine is an essential mineral for the thyroid, which is found in seafood and seaweed. Thyroid hormones are made using iodine and therefore it is essential for their production. The RDA of iodine is 140-500μg per day. Seaweeds are a great addition to food, or taken as a supplement to support your thyroid. Xandra and I both have a ground, dried seaweed shaker in our kitchens to add extra flavour and nutrients to our meals. 

The top 5 sources of iodine:

  •  Seaweed (3000-200,000μg, per 100g)
  • Haddock (323.7μg, per 100g)
  • Cod (191.6μg, per 100g)
  • Kefir (50μg, per 100g)
  • Eggs (50μg, per 100g)


L-tyrosine is an important amino acid that is needed to make thyroid hormone. Without enough iodine or tyrosine, our bodies cannot make thyroid hormone. L-tyrosine is found in dairy, meats, fish, eggs, nuts, beans and wheat. L-tyrosine supplements are also shown to help brain function when stressed12 and can help us to multitask.13 The RDA of tyrosine is 33mg per kg of body weight per day (for a 70kg man this would equate to 2310mg). The maximum safe upper limit for supplementing L-tyrosine is currently unknown, but up to 300mg/kg has been shown to be used safely.

The top 5 sources of L-tyrosine:

  • Parmesan (1995mg, per 100g)
  • Meat – beef or lamb, roasted (1386mg, per 100g)
  • Salmon – cooked (1157mg, per 100g)
  • Chicken – breast, cooked (1155mg, per 100g)
  • Pumpkin seeds (1093mg, per 100g)


Low levels of magnesium seem to cause a decrease in T4 (thyroid hormone) levels15 and magnesium supplements can help to raise T4 levels.15 The RDA is 270-400mg per day. Magnesium deficiency occurs more commonly in those with bowel diseases and type 2 diabetes.

The top 5 sources of magnesium:

  • Almonds – dry roasted (281mg, per 100g)
  • Cashews – roasted (292mg, per 100g)
  • Pumpkin seeds (262mg, per 100g)
  • Peanuts – dry roasted (176mg, per 100g)
  • Spinach – boiled (79mg, per 100g)

omega 3 fats

These can protect brain function against the negative effects of hypothyroidism, improving memory14 and can improve the effectiveness of thyroid hormone in the body,16 so may improve the symptoms of hypothyroidism. There are several different types of omega 3’s, including ALA (alpha-linolenic acid), which is present in plant oils, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), which are present in fish oils. Raising our levels of EPA and DHA from fish oils helps us to reduce inflammation and improve our overall health.

Krill oil is the most bioavailable (most easily used by the body) form of omega 3.17 The recommended daily amount of omega 3 (mainly from DHA and EPA) is 500mg per day. If you are not eating fish regularly, then you need up to four times as much ALA to get the balance of omega 3’s. Up to 4000mg of omega 3 daily can be taken safely and is recommended for some health conditions.

The top 5 sources of omega 3:

  • Krill oil (42000mg, per 100g as EPA & DHA)
  • Mackerel (1294mg, per 100g s EHA & DPA)
  • Salmon (1071mg, per 100g as EPA & DHA)
  • Flaxseed (24200mg, per 100g as ALA)
  • Chia seed (17830mg, per 100g as ALA)
  • Walnuts (7992mg, per 100g)


One of the most important minerals for the thyroid, selenium is essential for a healthy thyroid and improves the symptoms of hypothyroidism in Hashimoto’s disease.18 Taking selenium as a supplement improves levels of anti-thyroid antibodies and can improve thyroid function, especially in pregnancy.19 The RDA is 60μg-75μg and up to 350μg can safely be taken daily.

The top 5 sources of selenium:

  • Brazil nuts (1820μg, per 100g)
  • Halibut – cooked (55.4μg, per 100g)
  • Sunflower seeds (53μg, per 100g)
  • Sardines (52.7μg, per 100g)
  • Shitake mushrooms – cooked (24.8μg, per 100g)


Another critical mineral for the thyroid gland, zinc supplements can improve T3 levels and decrease TSH levels and improve conversion from T4 to T3.20 Zinc needs to be taken daily, as the body has no ability to store it. Vegetarians and those with digestive problems are more likely to be low in zinc. The RDA is 7-11mg daily, with a daily dose of up to 25mg daily considered to be safe.

The top 5 sources of zinc:

  • Oysters (90.5mg, per 100g)
  • Pumpkin seeds (7.6mg, per 100g)
  • Crab (7.6mg, per 100g)
  • Cashew nuts – raw (5.8mg, per 100g)
  • Beef – mince, cooked (4.8mg, per 100g)
  • Chickpeas – tinned (1.5mg, per 100g)

q&a with jess

I have hypothyroidism. Should I supplement all of these, or try different combinations to see if any help? How long does supplementing these take to show the benefits?

We would encourage that you take a good multivitamin, high in easily-absorbed forms of B vitamins, like Ultimate Pro. as well as additional magnesium (or regular baths with a cup of magnesium flakes or Epsom salts), a fish-based omega 3 supplement and a vitamin D supplement if tests show that you are deficient. (You can have your vitamin D levels checked with your doctor – aim for a measurement of greater than 70nmol/L.)

Thyroid changes can be slow, so it can take at least six to eight weeks to notice any positive changes. The best route is to supplement these for three months and then retest your levels to see if the changes show improvements. If you have thyroid issues, it’s always worth considering reducing inflammation through dietary changes.


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