Advice concerning correct nutrition in hypothyroid conditions can be confusing and contradictory. Here we present information based on both clinical studies and on clinical experience.

A variety of nutritional factors may affect your thyroid function. In order to make informed choices you need to know whether you have autoimmune thyroiditis, which is diagnosed by the presence of thyroid antibodies in the blood. It is important to assess both your thyroid function blood results, and your symptoms and well-being, in order to establish the most appropriate diet and supplements for you.

Positive nutritional influences on thyroid function

Vitamin D

• Attracting much recent interest from both orthodox and complementary medicine practitioners Vitamin D has been shown to be a common deficiency in a range of autoimmune and inflammatory disorders including Rheumatoid Arthritis, and Grave's disease (Yamashita, et al, 2001).
  
• Testing for Vitamin D status should be for the circulating form of calcidiol 25(OH)D, (Vasquez, Manso, and Cannell, 2004), this test is available through us
  
• If you have autoimmune thyroiditis we recommend Vitamin D testing
  
• Supplementation should be in the form of cholecalciferol (D3) and should continue for at least 6 months for maximum benefit (Vasquez, Manso, and Cannell, 2004)

Selenium

• Supplementation has been shown to reduce levels of thyroid antibodies but requires doses over 100ug daily (Turker, Kumanlioglu, Karapolat, & Dogan, 2006).
  
• Selenium is required for production of thyroid hormones, and conversion of thyroxine (T4) to the active thyroid hormone triiodothyronine (T3)

Glycaemic Index (GI) diet

• Refined sugars and high glycaemic index foods destabilise blood glucose, causing swings of high and low blood sugar. This stimulates production of the stress hormones adrenaline and cortisol whenever the blood sugar dips
  
• High cortisol encourages muscle breakdown in order to increase glucose supply to the brain. Reduced muscle mass means slower metabolism and weight gain
  
• High cortisol is especially associated with abdominal weight gain
  
• High cortisol levels have been shown to impair conversion of T4 to T3
  
• Stabilising blood sugar stabilises production of the stress hormones adrenaline and cortisol, this can be achieved with the GI diet or with supplements
  

Supplements to improve glucose metabolism

• Chromium has previously been demonstrated to improve glucose metabolism in Type 2 Diabetes Mellitus (Martin, et al, 2006) (Jain, Patel, Rogier, & Jain, 2006) (Vladeva, Terzieva, & Arabadjiiska, 2005) (Rabinovitz,et al, 2004)
  
• Cinnamon has previously been demonstrated to improve glucose metabolism in Type 2 Diabetes Mellitus (Khan, et al, 2003) (Mang, et al, 2006)
• Magnesium has been shown in a meta-analysis of 9 randomised double-blind controlled trials to improve glucose metabolism (Song, et al, 2006)
  

Adrenal support

• Symptoms of adrenal and thyroid dysfunction often overlap, and unstable blood sugar and stress are common themes in both conditions
  
• Herbs and nutrients that benefit the adrenal glands may benefit thyroid function

Negative nutritional influences on thyroid function

Fluoride

• Found in toothpaste, tea, and tap water, fluoride is chemically related to iodine and may block iodine receptors in the thyroid

Chlorine

• Found in tap water, chlorine is chemically related to iodine and may block iodine receptors in the thyroid

Gluten

• One of the proteins found in wheat, studies show an association between gluten intolerance and autoimmune thyroid disease
  
• Undiagnosed gluten intolerance may be a trigger for underlying autoimmune disease
  
• Blood tests for gluten intolerance have until recently been considered unreliable, but technology is improving and new generation tests have emerged, however no single test is completely reliable
  
• If you have autoimmune thyroiditis our advice is to have a Gluten Evaluation Profile blood test which includes 5 different tests of gluten sensitivity, including tissue transglutaminase
  

Goitrogens

• Some foods are regarded as goitrogenic meaning that they contain enzymes which may stimulate the growth of a goitre, block the absorption of iodine to the thyroid, and may act in the same way as anti-thyroid drugs and disable thyroid function
  
• These are millet, peanuts, pine nuts, soya, cassava, peaches, pears, rape seed oil, and vegetables of the brassica family including cabbage, broccoli, cauliflower, brussel sprouts, spinach, mustard greens and turnips.
  
• Cooking appears to disable the enzymes, so the best advice is
  
• Avoid the millet, peanuts, pine nuts, rape seed oil and soya
  
• Enjoy all the fruit and vegetables in moderate amounts provided that they are cooked.
  
• If your symptoms are severe you may want to avoid goitrogenic foods completely for a time

Soya

• Soya products are added to many foods and may be labelled as vegetable protein or vegetable oil. Soya is a goitrogen (see above) and is best avoided in thyroid disease
  

Sugar

• Refined sugars and high glycaemic index foods destabilise blood glucose, causing swings of high and low blood sugar. This stimulates production of the stress hormones adrenaline and cortisol whenever the blood sugar dips
  
• High cortisol encourages muscle breakdown in order to increase glucose supply to the brain. Reduced muscle mass results in slower metabolism and weight gain
  
• Cortisol also impairs conversion of T4 to T3

Controversial nutritional influences on thyroid function

Iodine

• Is frequently advised as a supplement to stimulate production of thyroid hormones. This is based on the knowledge that iodine is deficient in the soil in areas where hypothyroid disease prevails. However in the UK and USA today the commonest cause of hypothyroid is autoimmune thyroiditis which is not caused by iodine deficiency.
  
• Excess iodine also causes thyroid problems
  
• The mechanisms of autoimmune thyroid disease are not yet fully understood but it appears that the thyroid gland requires rest. Giving synthetic thyroxine appears to be beneficial in this sense and antibody levels may drop during thyroxine treatment. This has also been shown to be true for patients who have positive thyroid antibodies and normal thyroid function (Aksoy, et al, 2005). Stimulating the thyroid with high levels of iodine may aggravate autoimmune thyroiditis
  
• We do not advise taking iodine containing supplements if you have autoimmune thyroid disease
  
• However iodine deficiency is still reported in the UK (Kibirige, et al, 2004), this is thought to be due to soil depletion, and because people are reducing their salt intake for health reasons
  
• Fish and shellfish provide dietary iodine

Kelp

• Recommended by some practitioners for it's naturally high iodine content, the same cautions apply as for supplemental iodine (see above)
  
• We do not advise taking kelp or supplements containing it if you have autoimmune thyroid disease

Fibre

• Our needs for adequate fibre increase in hypothyroidism in order to prevent constipation and high lipid levels.
  
• Fibre can also interfere with the absorption of thyroxine.
  
• We advise maintaining a high fibre diet with as constant a level of fibre as possible so that medication levels can be stabilised accordingly
  

L-tyrosine

• An amino acid which is a precursor of T4 and T3, L-tyrosine is usually easily obtained from diet, there are no published studies on the effects of supplementing in hypothyroidism

Nutrition and T4 (thyroxine)
Certain foods interfere with the absorption of T4

• T4 should ideally be taken at the same time each morning 1 hour before eating breakfast
  
• Iron supplements & multivitamins which contain it should not be taken within 3 hours of thyroxine as iron competes with thyroxine for absorption
  
• Calcium supplements & calcium fortified foods should not be taken within 3 hours of thyroxine as calcium competes with thyroxine for absorption
  
• Soya reduces absorption of thyroxine, if you do choose to eat soya products don't have them within 3 hours of taking your thyroxine
  
• Lemon balm may interfere with thyroxine absorption and should be avoided, check any herbal teas that you drink regularly to see if lemon balm is an ingredient

the complementary medicine practice offers

• Complete thyroid function profile blood tests
  
• Traditional Chinese Medicine diagnosis alongside blood tests
  
• A consultation to assess all factors affecting your well-being and metabolism
  
• Testing for nutritional deficiencies such as Vitamin D
  
• Gluten Evaluation Profile testing
  
• Liaison with endocrinologists and other medical professionals
  
• An individual nutritional protocol designed for you
  
• Acupuncture treatment to help balance and stabilise energy

References
Aksoy,D.Y., Kerimoglu, L.J., Okur, H., Canpinar, H., Karaagaoglu, E., Yetgin, S., Kansu, E., Gedik, O., 2005, Effects of prophylactic thyroid hormone replacement in euthyroid Hashimoto's thyroiditis, Endocr J. Jun;52(3):337-43

Jain, S.K., Patel, P., Rogier, K., Jain, S.K., 2006, Trivalent chromium inhibits protein glycosylation and lipid peroxidation in high glucose treated erythrocytes, Antioxid Redox Signal, Jan-Feb;8(1-2):238-41

Khan, A., Safdar, M., Ali Khan, M.M., Khattak, K.N. Anderson, R.A., 2003, Cinnamon improves glucose and lipids of people with type 2 diabetes, Diabetes Care, Dec;26(12):3215-8

Kibirige, M.S., Hutchinson, S., Owen, C.J., Delves, H.T., 2004, Prevalence of maternal dietary iodine insufficiency in the north east of England: Implications for the fetus, Arch Dis Child Fetal Neonatal, Ed, Sep;89(5):F436-9

Mang, B., Wolters, M., Schmiddt, B., Kelb, K., Lichtinghagen, R., Stichtenoth, D.O., Hahn, A., 2006, Effects of a cinnamon extract on plasma glucose, HbA, and serum lipids in Diabetes Mellitus type 2, Eur J Clin Invest, May;36(5):340-4

Martin, J., Wang, Z.Q, Zhang, X.H., Watchel, D., Volaufova, J., Matthews, D.E., Cefalu, W.T., 2006, Chromium picolinate supplementation attenuates body weight gain and increases insulin sensitivity in subjects with type 2 diabetes, Diabetes Care, Aug;29(8):1826-32

Rabinovitz, H., Friedensohn, A., Leibovitz, A., Gabay, G., Rocas, C., Habot, B, 2004, Effect of chromium supplementation on blood glucose and lipid levels in type 2 diabetes mellitus elderly patients, Int J Vitam Nutr Res, May;74(3):178-82

Song, Y., He, K., Levitan, E.B., Manson, J.E., Liu, S., 2006, Effects of oral magnesium supplementation on Glycaemic control in Type 2 diabetes: a meta-analysis of randomised double-blind controlled trials, Diabet Med, Oct;23(10);1050-6

Turker, O., Kumanlioglu, K., Karapolat, I., Dogan, I., 2006, Selenium Treatment in autoimmune thyroiditis: 9 month follow-up with variable doses, J. Endocrinology, Jul;190(1):151-6

Vasquez, A., Manso, G., and Cannell, J., 2004, The Clinical Importance of Vitamin D (Cholecalciferol): A Paradigm Shift with Implications for all Healthcare Providers, Alternative Therapies, Sept/Oct, Vol10,No5:28-36

Vladeva, S.V., Terzieva, D.D., Arabadjiiska, D.T., 2005, Effect of chromium on the insulin resistance in patients with type II Diabete Mellitus, Folia Med. 47(3-4):59-62

Yamashita, H., Noguchi, S., Takatsu, K., Koike, E, Murakami, T., Watanabe, S., Uchino, S., Yamashita, H., Kawamoto, H.,2001, High prevalence of Vitamin D deficiency in Japanese female patients with Graves's disease, Endocr J, Feb;48(1)