Night blindness: FAAS offers mineral clues

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  • Published: Oct 15, 2011
  • Author: David Bradley
  • Channels: Atomic
thumbnail image: Night blindness: FAAS offers mineral clues

Mineral deficiency

Researchers have used flame atomic absorption spectroscopy (FAAS) to show that children who suffer night blindness are commonly deficient in several minerals but also have elevated sodium levels.

Almost 14 million children worldwide have some degree of blindness because of a dietary deficiency of vitamin A. The vitamin is strictly speaking a complex of vitamin A retinol, retinal, and four carotenoids including beta carotene. It is essential to formation of the light-absorbing molecule retinal, which is needed in low-light (scotopic vision) and colour vision. Retinol is obtained from retinyl ester in meat whereas the carotenes are obtained from plant sources.

Unfulfilled potential

According to researchers in Pakistan, night blindness in children specifically is actually a multifactorial problem, although childhood nutritional deficiency is the most common factor, particularly in underdeveloped countries. They point out that vitamin and mineral deficiencies prevent more than two billion people from reaching their full intellectual and physical potential. Of course, a better understanding of the impact of this level of nutritional deficiency on significant physiological and pathological processes might not alleviate the problem but could be used to highlight specific issues that might then be address through more targeted food aid efforts. The changes reflected in the composition of biological samples composition is open to analytical testing.

Hassan Imran Afridi, Tasneem Gul Kazi, Naveed Kazi, Ghulam Abbas Kandhro, Jameel Ahmed Baig, Abdul Qadir Shah, Sumaira Khan, Nida Fatima Kolachi, Sham Kumar Wadhwa and Faheem Shah of the National Center of Excellence in Analytical Chemistry, at the University of Sindh, in Jamshoro, Pakistan, have turned to FAAS to analyse such samples with the aim of identifying patterns correlating night blindness with mineral profile.

The team used flame atomic absorption spectrometry (FAAS) with an air/acetylene flame to compare the levels of magnesium (Mg), calcium (Ca), potassium (K), and sodium (Na) in scalp hair, serum, blood, and urine of boys and girls with night blindness across two age ranges, 1-5 and 6-10 years. They compared the results sex- and age-matched control samples. The team developed a microwave-assisted wet acid digestion procedure to pre-treat their samples for Mg, Ca, K, and Na testing and validated the approach against conventional wet digestion and certified reference samples.

Avoiding night blindness

"The results indicated significantly lower levels of Mg, Ca, and K in the biological samples (blood. serum, and scalp hair) of male and female children with night blindness and higher values of Na compared with control subjects of both genders," the team says. On this basis, they suggest that the data could be used to guide healthcare workers in the investigation of specific essential mineral deficiencies for the prevention of childhood night blindness.

Hassan Imran Afridi from webpage
Hassan Imran Afridi

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