According to the most recent Healthy Ireland Survey, normal-weight adults are in the minority [1]. The association between obesity and subsequent ill health, most notably cardio-vascular, cancer and diabetes, is well known. Overweight or obese status is also associated with diminished immune function, increase in inflammatory markers such as C-reactive protein and fibrinogen in both adults and children, changes known to increase vulnerability to other infections. The poorer prognostic risk in obese individuals from H1N1 influenza has also now been suggested with COVID-19 [2] with the higher rate of obesity in older adults in Italy proposed as a putative explanation to account for the excess deaths in patients with COVID-19 compared to China [3].

Significant changes in dietary habits have led to current diets high in fat, salt and sugar, with minimum essential nutrients or dietary fibre. Deficiencies in vitamins such as A, C, D and E, along with lower levels of iron and zinc, have all been reported. These micro-nutrients are essential to health and possess anti-inflammatory, antioxidant, and even antiviral properties, salient given the current times [4].

Evidence is emerging linking vitamin D deficiency to increased infectivity, morbidity and mortality in COVID-19 [5], in parallel to benefits from supplementation [6]. Vitamin D is also considered neuroprotective, reducing oxidative stress, modulating neuronal excitability and stimulating nerve growth, with vitamin D receptors abundant in many parts of the brain (Table 1). Deficiency states have been implicated in many psychiatric illnesses [6].

Vitamin D has particular relevance for the Irish population, with high rates of insufficiency by virtue of poor diet and poor UV exposure, especially true in the winter months [7]. Current rates of vitamin D supplementation among adults in Ireland are low (ranging from 9-18%) and the FSAI (Food safety authority of Ireland) recommended dosage of 10 mcg per day well below international recommendations. Given the onset of winter months in Ireland, with weather often a deterrent to outdoor activity, vitamin D levels may plummet in many. Current Level 5 restrictions imposed following upsurges in COVID-19, further limits gym activity, social engagement and other mood boosting activities. Increased sedentary time at home might risk increased food intake and weight gain and poorer mental health. Although the best advice to reduce one’s risk from COVID-19 aligns with the HSE advice of social distancing, good hand and cough hygiene, reminding our patients of their ability to modulate their mood and health by careful attention to dietary intake, nutritional supplementation and other health-promoting habits such as exercise, sleep and relaxation are important (Table 1).

Table 1 Optimising nutrition and wellbeing
Full size table
FormalPara Conclusion

The disproportionate impact of both influenza and COVID-19 in patients with obesity is a concern as we approach the winter months. Emerging evidence supports dietary manipulation on physical and mental health in general and should become part of routine clinical practice.