Manganese (Mn) is a trace mineral that is vital for the human body, but is only needed in small amounts, as it has the potential to be very toxic. Manganese is involved in the synthesis and activation of many enzymes and in the regulation of the metabolism of carbohydrates, amino acids and lipids. In addition, Mn is one of the required components for Mn superoxide dismutase (MnSOD) that is mainly responsible for scavenging reactive oxygen species (ROS) in mitochondrial oxidative stress. Mitochondria are the major place where physiolgoical and pathological cellular ROS are produced. When excessive ROS accumulate abnormally, it contributes to the oxidative damage found in several neuropathological conditions. If mitochondria are impaired or dysfunctional, ROS production will be further increased and will exacerbate the oxidative stress in mitochondria (1).
Manganese is also required for normal skeletal development and cartilage synthesis. Wound healing is also impacted by manganese, as the synthesis of collagen in skin cells is dependent on the presence of adequate manganese. Manganese is considered anti-osteoporotic and anti-arthritic.
Both Mn deficiency and intoxication are associated with adverse metabolic and neuropsychiatric effects. Over the past few decades, the prevalence of metabolic diseases, including type 2 diabetes, obesity, insulin resistance, atherosclerosis, hyperlipidemia, nonalcoholic fatty liver disease (NAFLD), and hepatic steatosis, has increased dramatically. Previous studies have found that ROS generation, oxidative stress, and inflammation are critical for the pathogenesis of metabolic diseases. In addition, deficiency in dietary Mn as well as excessive Mn exposure could increase ROS generation and result in further oxidative stress (1).
Deficiency in manganese was once considered rare, but it is now estimated that up to 15% of the population may be deficient in manganese caused by improper diet and eating habits. Deficiency in manganese may lead to various health problems which could include bone malformation, eye and hearing probles, increased cholesterol, hypertension, infertility, cardiovascular issues, memory loss, hearing loss, muscle cramping and tremors. Other deficiency has also been linked to myasthenia gravis.
Manganese toxicity symptoms mimic those of Parkinson’s Disease with permanent neurological damage. It may also precipitate hypertension in patients over 40, and significant rises in manganese are found in patients with epatitis, cirrhosis, dialysis patients and victims of heart attack. Early signs of toxicity include loss of appetite, impaired memory, and mask-like facial expressions. Excess manganese will reduce iron absorption.
Blackstrap molassess, 1 tbsp, 1.53 mg
Pineapple, raw, 1/2 cup, 1.28 mg
Oatmeal, 1 cup, 1 mg
Pecans, 1 oz, 1.12 mg
Brown rice, 1/2 cup, 0.88 mg
Spinach, 1/2 cup, 0.84 mg
Almonds, 1 oz, 0.74 mg
Peanuts, 1 oz, 0.59 mg
Sweet Potato, 1/2 cup, 0.55 mg
Lima beans, 1/2 cup, 0.48 mg
Tea, green, 1 cup, 0.41-1.6 mg
Tea, black, 1 cup, 0.18-0.77 mg
Estimated average dietary manganese intakes range from 2.0 to 3.0 mg/day for men and 1.6-1.8 mg/day for women. People eating vegetarian diets may have higher intakes. Foods high in phytic acid or oxalic acid may reduce manganese absorption.