Looking After Your Thyroid in a Toxic World

A toxin is any substance that creates irritation and/or harmful effects in the body, undermining our health or stressing our biochemical or organ functions. In the 21st century, more than at any other time in history, we are bombarded with toxins. In addition to environmental pollution, there are many toxins in food sources - pesticides, plasticisers, additives, both in food and products, hormones in intensive farmed meats, etc.

Within our bodies, we have to 'deal' with these substances for which we were not designed. The true long-term impact of this toxicity on human physiology is yet to be revealed. However, in all health disciplines throughout time, the association between toxicity and disease has been clearly defined.

When the liver is overloaded, as it commonly is with the modern diet, it cannot successfully eliminate everything we are subjected to both internally and externally. Anything that cannot be eliminated and excreted is locked up safely in the fat stores.

As well as producing symptoms of fatigue, bloating, excess weight, feeling low, skin conditions, PMT and bad breath, the thyroid can also be affected.

Here is a list of various types of toxins:

Industrial Chemicals

At least 150 industrial chemicals have been shown to result in the reduction in TSH and/or T4 (Dufour et al. 2020). Many compounds including polychlorinated biphenyls (PCBs), bisphenol A (BPA), phthalates, brominated flame retardants, perfluorinated chemicals and triclosan show thyroid-disrupting characteristics (Boas et al. 2012).

Fluoride

Fluoride is an antagonist to iodine and in excess can inhibit proper production of thyroid hormones (Kheradpisheh et al. 2018)

Heavy Metals

Heavy metals such as arsenic, cadmium, lead and mercury are environmental toxins that interfere with the normal functioning of the thyroid gland. Arsenic and cadmium have been shown to inhibit thyroid peroxidase (TPO) activity whilst lead and mercury affect uptake of iodide into the thyroid gland and alter the metabolism of thyroid hormones (Babić Leko et al. 2021).

Smoking

Most studies show that smoking decreases TSH levels and increases T3 and T4 levels in smokers. The mechanism through which cigarette smoking affects TSH and thyroid hormone levels is still unclear but one of the proposed mechanisms is that

The cyanide in tobacco is transformed into thiocyanate, and thiocyanate has been observed to decrease protein-bound T4 levels and consequently increase fT4 levels. (Babić Leko et al. 2021).

Surprisingly, smoking during pregnancy has been shown to decrease the risk of appearance of autoimmune antibodies TPOAb and TgAb although this protective effect disappears a few years after cessation. Furthermore, prevalence of postpartum thyroiditis is increased from smoking during pregnancy (Ferrari et al. 2017) and alarmingly, maternal smoking has been shown to disrupt fetal thyroid development (Filis. et al. 2018).

Is there a Cumulative Effect?

Most toxicological research on endocrine disruptors have been focused on single chemical effects. However, a growing number of investigations show effects of toxicity can be additive, i.e. “the combination of a sufficient number of chemicals at individual concentrations associated with zero effect will jointly produce an observable effect” (Dufour et al. 2020).

It is therefore important to try to reduce our overall toxic load as much as we can if we are to prevent disruption of our hormones.

What we can do

The more inflammation in your body caused by other dietary and lifestyle choices, the more taxed this system is and the higher your risk of becoming immune reactive to chemicals and developing an autoimmune condition such as Hashimoto’s thyroiditis or Graves’ Disease. You can minimise your risk of developing an immune reaction to common chemicals and heavy metals by promoting a strong antioxidant system to protect your cells from toxins.

Reduce exposure to environmental chemicals

Fluoride exposure in the water supply has the potential to disrupt thyroid functioning. Adequate iodine intake may mitigate this effect but if iodine deficient then fluoride can be a culprit of thyroid disfunction (Malin et al. 2018). In hypothyroidism consider using fluoridated toothpaste only twice per week if necessary and non-fluoridated the rest of the time.

Exposure to environmental chemicals such as petrol fumes and chemical solvents, a diet low in flavonoids and fibre and a sedentary lifestyle all deplete the antioxidant system. To support the body’s antioxidant system adopt an anti-inflammatory diet such as The Mediterranean Diet, and lifestyle.

Nutrition

Colourful fruit and vegetables such as berries, red cabbage and greens are high in flavonoids which support your antioxidant system.

High sulphur foods such as garlic, onions and asparagus are also beneficial, as these are high in antioxidants and improve the function of liver sulfation pathways that help clear out chemicals.

Exercise

When you exercise, you actually produce inflammatory free radicals which your body responds to by turning on antioxidant enzyme pathways and increasing the production of antioxidants. However, over-exercising will have the opposite effect and increase inflammation, depleting your antioxidants.

As you can see, toxins are everywhere and to ensure that your thyroid is healthy, it’s a good idea to be aware of where they are and reduce them if possible.

References

Babić Leko, M. Gunjača, I. Pleić, N. et al. (2021). ‘Environmental factors affecting thyroid-stimulating hormone and thyroid hormone levels,’ International Journal of Molecular Sciences, 22 (12), 6521.

Boas, M. Feldt-Rasmussen, U. & Main, K. (2012). ‘Thyroid effects of endocrine disrupting chemicals,’ Molecular and Cellular Endocrinology, 355, 2, pp.240-248.

Dufour, A. Pirarda, C. Petrossiansc, P. et al. (2020). ‘Association between mixture of persistent organic pollutants and thyroid pathologies in a Belgian population,’ Environmental Research, 181.

Ferrari et al. (2017). ‘Environmental influences on thyroid diseases,’ Frontiers in Endocrinology, 8, 50.

Filis, P. Hombach-Klonisch, S. Ayotte, P. et al. (2018). ‘Maternal smoking and high BMI disrupt thyroid gland development,’ BMC Med, 16, 194.

Kheradpisheh, Z. Mirzaei, M. Mahvi, A. et al. (2018), ‘Impact of drinking water fluoride on human thyroid hormones: A case- control study,’ Scientific Reports, 8, 2674.

Malin, A. Riddell, J. McCague, H. et al. (2018). ‘Fluoride exposure and thyroid function among adults living in Canada: Effect modification by iodine status,’ Environ Int. 121(Pt 1) pp.667- 674.