Soil-type influences human selenium status and underlies widespread selenium deficiency risks in Malawi

Area of Science:

• Human Nutrition
• Environmental Science
• Public Health

Background:

• Selenium (Se) is a vital micronutrient for human health, crucial for immune function and antioxidant defense.
• Dietary selenium intake and status data are limited across Africa, despite indications of widespread deficiency.
• Malawi's soil types may contribute to insufficient selenium levels in locally grown crops.

Purpose of the Study:

• To assess the prevalence and risk of selenium deficiency in Malawi.
• To investigate the relationship between soil type and selenium status in adults.
• To estimate the proportion of the Malawian population at risk of inadequate dietary selenium intake.

Main Methods:

• Assessed selenium status in adults consuming food from areas with contrasting soil types.
• Analyzed food balance sheets and food composition data.
• Estimated population-level risk of dietary selenium inadequacy.

Main Results:

• Selenium deficiency is likely endemic in Malawi, as evidenced by the selenium status of adults.
• >80% of the Malawi population is at risk of inadequate dietary selenium intake.
• Significant risk of selenium inadequacy also identified in other Southern African countries and across Africa.

Conclusions:

• Malawi's soils generally cannot provide adequate selenium for human nutrition through crops.
• Interventions, such as selenium-enriched fertilizers, should be considered to address widespread selenium deficiency.
• Further research into the cost-effectiveness of selenium supplementation strategies is warranted.