GEOGRAPHIC DISTRIBUTION OF GEOLOGICALLY BIOAVAILABLE SELENIUM: CORRELATIONS WITH HEALTH AND DISEASE

This poster depicts known geographic distribution of bioavailable selenium (Se) derived from geologic materials. Because Se is an essential micronutrient, a map correlating disease with deplete Se status was found useful in understanding the role of nutritional Se in global human health.

Geologic Se was first recognized in the U.S. for its toxic effects – on livestock and, later, waterfowl. Ill animals were found to have grazed vegetation growing on Se-soils derived from Cretaceous marine shales and conglomerates. By the early 1970’s, Se was discovered to be a component of the enzyme glutathione peroxidase (GPx), a metabolic antioxidant. Subsequently, Se was determined to be an essential micronutrient, critical to the function of over two dozen human proteins and enzymes. The conventional biomarker for nutritional Se is blood plasma; 95 mcg Se/L in blood plasma is gauged sufficient to optimize GPx activity. Data from the literature indicate that low Se status is globally widespread.

Deficient dietary Se is known or implicated in the etiology of numerous health effects, e.g., osteoarthropathy (Kaschin-Beck disease in China); thyroid-hormone metabolism; low fertility; depression; cognitive decline; and diseases of immunosuppression, including cancers. Multiple factors link nutritionally deplete Se and disease, e.g., nutritional I2 deficiency, leading to hypothyrodism and cretinism; and viral infections: coxsackie virus B3 inducing cardiomyopathy (Keshan disease in China); human immunosuppression viruses (HIV-1 and 2), associated with <85 mcg Se/L blood plasma; hepatitis B and C viral activity; and various influenzas, especially those originating in Asia. Adequate physiologic Se status contributes to prevention of these illnesses. Furthermore, prescribed dietary Se may play a role in preventing or decreasing some types of cancers.

Nutritional Se occurs from consuming Se-bioaccumulating foodstuffs, -- or dietary supplements. Data on Se bioavailability is correlated with the physiological Se status of the human population in that region. This information is compared with the health of populations and known diseases associated with nutritionally deplete Se status.