Thyroid nodules describe the growth of abnormal cells on the thyroid gland(i). By aged 60 thyroid nodules may be seen in up to 50% of the population suggesting that increasing age, perhaps as a result of increased oxidative stress and inflammation appears to be risk factor for their presence.
Thyroid nodules display gender disparity having been observed to occur more frequently in the female sex thus highlighting the influencing role of female hormones. Check your hormonal status and see what’s going on. Experimental research suggests that oestrogen may increase the growth of thyroid stem cells(ii). Also check there is adequate thyroid hormone available as treatment with thyroxine (T4) has been shown to reduce the incidence of nodules; in individuals with benign thyroid nodules but normal thyroid function the use of thyroxine is obviously controversial, however you can support your thyroid with all the nutrients known to support thyroid health to ensure you are making enough T4 and T3.
Thyroid nodules are also seen more frequently in the presence of nutritional deficiencies including selenium and iodine, both of which are known to be essential for optimum thyroid health. Supplementation with iodine and selenium been shown to reduce the incidence of nodules in some but not all studies, however nodules still occur in iodine sufficient areas, suggesting other causes for their presence.
Another recently identified causative factor identified includes impaired glucose metabolism and resultant insulin resistance. The presence of insulin resistance has been demonstrated to increase risk of euthyoid nodular goitre and has been associated with an increase in thyroid volume, with larger thyroid volume demonstrated in those with glucose metabolism disorders such as type-2 diabetes and insulin resistance compared to controls(iii). A positive association has also been demonstrated between insulin resistance and risk of thyroid cancer(iv).
IR plays an important role in thyroid nodule vascular growth. Insulin functions as a growth factor in combination with thyroid-stimulating hormone (TSH) stimulating the proliferation of thyroid cells known as thyrocytes. Insulin resistance has been shown to cause specific changes to the distribution, construction, and density of nodular vascularisation contributing to the growth and the progression of thyroid nodules(v).
A preliminary study involving 100 newly diagnosed subjects with insulin resistance prescribed a standard diet and exercise program in addition to 1,700 mg/day of metformin therapy for 6 months observed a decrease in insulin resistance, mean thyroid volume and nodule size. BMI and waist circumference also decreased, suggesting that weight reduction and a decrease in insulin resistance to play a pivotal role in thyroid health(vi).
In a randomised placebo controlled trial involving 89 individuals with pre-diabetes, treatment with Metformin for 3 months was shown to reduce the size of small solid thyroid nodules, prevent an increase in thyroid volume and also decrease serum TSH however this was only seen in people with a TSH >2.5 μU/ml(vii).
In light of the fact that Metformin is associated with side effects including vitamin B12 deficiency and thus in keeping with naturopathic philosophy to first do not harm, naturopathic management of thyroid nodules and concurrent insulin resistance is likely to respond well to a combination of lifestyle and nutrition-based therapy involving a high fibre, high mineral, low GI wholefood diet with particular emphasis on specific food which have demonstrated blood sugar balancing properties such as vinegar, cinnamon and blueberries as well as lifestyle techniques such as exercise and stress management. For more information and a tailor made plan specific for you book in to see your naturopath.
i. Paschou SA, Vryonidou A, Goulis DG. Thyroid nodules: Α guide to assessment, treatment and follow-up Maturitas. 2017 Feb;96:1-9
ii. Xu S, Chen G, Peng W, Renko K, Derwahl M. Oestrogen action on thyroid progenitor cells: relevant for the pathogenesis of thyroid nodules? 2013 Jun 1;218(1):125-33
iii. Duran AO, Anil C, Gursoy A, Nar A, Inanc M, Bozkurt O, Tutuncu NB. Thyroid volume in patients with glucose metabolism disorders Arq Bras Endocrinol Metabol. 2014 Nov;58(8):824-7.
iv. Malaguarnera R, Vella V, Nicolosi ML, Belfiore A. Insulin Resistance: Any Role in the Changing Epidemiology of Thyroid Cancer? Front Endocrinol (Lausanne). 2017 Nov 14;8:314
v. Wang K, Yang Y, Wu Y, Chen J, Zhang D, Mao X, Wu X, Long X, Liu C. The association between insulin resistance and vascularization of thyroid nodules J Clin Endocrinol Metab. 2015 Jan;100(1):184-92. doi: 10.1210/jc.2014-2723.
vi. Anil C1, Kut A, Atesagaoglu B, Nar A, Bascil Tutuncu N, Gursoy A. Metformin Decreases Thyroid Volume and Nodule Size in Subjects with Insulin Resistance: A Preliminary Study Med Princ Pract. 2016;25(3):233-6
vii. Karimifar M, Aminorroaya A, Amini M, Mirfendereski T, Iraj B, Feizi A, Norozi A. Effect of metformin on thyroid stimulating hormone and thyroid volume in patients with prediabetes: A randomized placebo-controlled clinical trial J Res Med Sci. 2014 Nov;19(11):1019-26.