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High plasma vitamin C concentrations at birth associated with low antioxidant status and poor outcome in premature
K M Silvers1, A T Gibson, H J Powers
1University Department of Paediatrics, University of Sheffield.
Insights
Plasma antioxidant activity at birth is a significant predictor of mortality in premature infants. High ascorbic acid levels may paradoxically reduce this protective effect, influencing infant outcomes.
Area of Science:
- Neonatal Medicine
- Biochemistry
- Nutritional Science
Background:
- Circulating antioxidant concentrations are crucial in understanding diseases affecting premature infants.
- Premature infants face unique health challenges, making the study of their physiological defenses critical.
Purpose of the Study:
- To investigate the relationship between plasma antioxidant activity at birth and mortality in premature infants.
- To explore the roles of plasma ascorbic acid and caeruloplasmin in neonatal antioxidant capacity.
Main Methods:
- Blood samples were collected from 49 premature infants within two hours of birth.
- Measurements included plasma ascorbic acid, caeruloplasmin, and in vitro plasma antioxidant activity (inhibition of lipid peroxidation).
- Statistical analysis considered gestational age and birth weight to assess predictors of mortality.
Main Results:
- Plasma antioxidant activity at birth showed a strong negative correlation with plasma ascorbic acid and the ascorbic acid to caeruloplasmin ratio.
- Despite adjustments for gestational age and birth weight, plasma antioxidant activity at birth significantly predicted mortality.
- Caeruloplasmin's ferroxidase activity contributes to plasma antioxidant capacity, but high ascorbic acid concentrations may diminish this activity.
Conclusions:
- Plasma antioxidant activity at birth is a critical factor influencing mortality risk in premature infants.
- The interplay between ascorbic acid and caeruloplasmin impacts neonatal antioxidant defense, with potential implications for infant health outcomes.
- Further research is warranted to elucidate the mechanisms by which ascorbic acid may modulate plasma antioxidant activity and affect infant survival.
Abstract:
Concentrations of circulating antioxidants may be important in the aetiology of disease in premature infants. Blood samples were taken from 49 premature infants within two hours of birth. Plasma ascorbic acid, caeruloplasmin, and the ability of plasma to prevent lipid peroxidation in vitro were measured. Plasma ascorbic acid concentrations at birth ranged from 26.3 to 185.4 mumol/l. Plasma antioxidant activity at birth (microliter plasma required to inhibit lipid peroxidation) showed a strong negative correlation with plasma ascorbic acid and the plasma ascorbic acid to caeruloplasmin ratio. After correcting for gestational age and birth weight, plasma antioxidant activity at birth remained a significant predictor of mortality. Such plasma antioxidant activity is partly determined by the ferroxidase activity of caeruloplasmin. This may be modulated by high concentrations of ascorbic acid which may inhibit the antioxidant activity of plasma and thereby influence outcome.