Immunity, environment And nutritional for winter
Seasonality is observed in almost all infectious diseases. This seasonality is observed in respiratory
infections such as influenza, to diarrhoeal diseases such as cholera and vector-borne diseases such as
malaria. Factors that are involved in the seasonality of infectious diseases are environment and host
Exposure to cold temperatures affects the physical, cellular, and molecular defenses against
pathogens in humans. Normal physical barriers to infection can be damaged by cold temperatures,
such as increased mucus viscosity and decreased ciliary action in the upper respiratory system.
Cutaneous barrier function upon cold exposure is also disrupted. Furthermore, exposure to cold
temperatures causes secretion of the stress hormones norepinephrine and cortisol, lymphocytosis
and decreased lymphocyte responses (part of adaptive immunity). The increased production of
corticosteroids and catecholamines following cold exposure impacts immune cell function negatively.
Norepinephrine especially is involved in many of the physiological and immunological changes
observed with cold temperature. Changes in immunological parameters similar to physiological
changes are dependent on the severity of the cold exposure. Several studies have found that exposure
to cold temperatures induces a decreased immune function and increased susceptibility to infection.
Seasonal variations in nutrition also occur in many settings, and a direct link between poor nutritional
status, reduced cell mediated immune responses and an increased risk of infection is well established
in children. Vitamin D levels are consistently lower in winter and spring months in temperate settings.
This vitamin D deficiency increases the risk of respiratory infection in children. The most specific effect
of vitamin D deficiency on immunity is a reduction in the antimicrobial peptide cathelicidin, a part of
the innate immune system, which is expressed in white blood cells and bronchial epithelial cells
present in the lung. Vitamin D can be obtained via dairy and animal products.
Boosting your immunity
Immunity can be boosted by eating food containing antioxidants. Vitamin A, C, E, carotenoids and
flavonoids are antioxidants we should eat in sufficient amounts to boost our immunity. These
antioxidants are found in coloured fruits and vegetables, like berries, green vegetables, pumpkins,
spinach and broccoli.
Author: dr. Vinod Sommandas, Wellbeing Tutor at Vedanta Wellbeing PhD
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