Published May 20 2013
Note: Most people reading this currently take nutritional supplements, and yet most people don’t have a good understanding about the vitamins and minerals they’re taking. Because of this, what I’ve decided to do is to write some articles which discuss the different roles of each of the vitamins and minerals in the body, and since this website focuses on thyroid and autoimmune thyroid conditions, I figured it would be a good idea to briefly discuss how they relate to thyroid health. This article will focus on the importance of manganese.
Compared with many of the other minerals in the body, there are only trace amounts of manganese in animal tissues (between 10 to 20mg). Manganese is involved in the function of numerous enzymes, and is also important for normal growth and development. This mineral is also essential for the repair of bones and connective tissue. Just about all of the minerals play a role in the health of the immune system, and manganese also seems to be important for optimal immune system health. Some studies also show that manganese can influence the levels of neurotransmitters, such as glutamate and GABA (1) [1]. Manganese superoxide dismutase is a manganese-containing enzyme, and is one of the main antioxidant enzymes responsible for neutralizing the toxic effects of reactive oxygen species (2) [2].
Most minerals are interactive, and one relationship of nutritional significance is the interaction between manganese and iron. Nonheme iron competes with manganese for absorption (3) [3]. I’ll talk about food sources later in this article, but whole grains and leafy green vegetables are supposed to be two of the richest dietary sources of manganese. However, these foods also contain high amounts of heme iron. Other nutrients which may affect the absorption of manganese include magnesium and phosphorus (4) [4] (5) [5].
How Does Manganese Relate To Thyroid Health?
Unlike many of the other vitamins and minerals I’ve discussed in the past, there is still a lot of uncertainty regarding how manganese relates to thyroid health. The production of thyroid hormone requires manganese, along with other minerals. As a result, a deficiency of manganese can potentially cause or contribute to a hypothyroid condition. However, too much manganese can also cause problems with thyroid hormone production.
One article I came across stated that “experimental findings point to the ability of manganese to interfere with deiodinase activity”, and this in turn would affect the amount of circulating thyroid hormone. (6) [6]. The same study stated that “dose-dependent goitrogenic effects of manganese have been illustrated”. I wouldn’t get too concerned about this, as this study was performed on mice and they were fed excessive amounts of manganese, and went on to develop goiter. This study also showed that a “high-accumulation of manganese in the pituitary gland resulted in a significant decrease in serum T4, T3, and in TSH concentrations”.
Another study I came across suggested that excessive manganese exposure may lead to adverse neurodevelopmental outcomes due to the disruption of thyroid homeostasis via the loss of dopaminergic control of TSH regulation of thyroid hormones, which in turn may alter thyroid hormone levels (7) [7]. All of these scenarios I brought up relate to excessive levels of manganese.
Food Sources of Manganese
As I mentioned before, nonheme iron will interfere with the absorption of manganese. So while whole grains and leafy green vegetables are excellent sources of manganese, the nonheme iron present in these foods will affect manganese absorption to some degree. In addition to the nonheme iron in whole grains, the phytic acid will also interfere with the absorption of nutrients. As a result, meats (organ meats) are one of the best source of manganese. Legumes are also good sources.
Supplementing With Manganese
The RDI of manganese is 15 to 50 mg. Some of the different forms of manganese include manganese gluconate, manganese sulfate, and manganese citrate, and manganese aspartate.
Manganese Toxicity
I commonly recommend a hair mineral analysis to my patients, and every now and then I’ll see very high manganese levels. Manganese toxicity from food or supplementation is rare, although manganese can be toxic when inhaled in the form of manganese oxide. Manganese sometimes is high in tap water, along with well water.
Hopefully you have a better understanding of the importance of manganese to your health. Unlike other minerals such as selenium, zinc, and iron, we don’t hear too much about manganese. But manganese has many important functions. While a deficiency in manganese can potentially lead to a hypothyroid condition, a manganese toxicity can also inhibit thyroid dysfunction. However, I’ve seen high levels of manganese on a hair mineral analysis in some of my hyperthyroid patients. One also needs to be aware that certain nutrients (i.e. iron and phosphorus) can interfere with the absorption of manganese.