Albandari Bin Ammar^1,, Nagat Eltoum¹, Abd Elmoneim Elkhalifa¹, Sayeda Fatima¹, Nagwan Mohamed Elhussein², Leo Rathinaraj Antony Soundararajan³, Majid Alkhalaf⁴, Momen Elshazley⁵, Sara Seifeldin⁶, Abdullah Alammar⁷

Long COVID is characterised by persistent symptoms following recovery from acute SARS-CoV-2 infection such as fatigue and muscle pain. Nutritional factors, including diet quality, malnutrition risk and micronutrient status, may influence post-recovery outcomes, yet evidence of this remains limited. This study examined the associations of diet quality, malnutrition risk, and serum levels of magnesium and vitamin D with persistent fatigue and muscle pain among COVID-19 survivors. A retrospective cohort study was conducted on 103 (51 males, 52 females) adults with a mean age of 55.13 ± 14.45 years, previously hospitalised for COVID-19 in the Ha’il region, Saudi Arabia. Data were collected from hospital records and a single post-recovery follow-up assessment conducted 1–3 years after discharge. Nutritional risk was evaluated using the Malnutrition Screening Tool, while dietary adherence and supplement use were assessed through structured questionnaire. Serum magnesium and vitamin D levels were measured at both admission and follow-up. Comparative analyses between participants with and without persistent fatigue or muscle pain were performed using chi-square and Mann–Whitney U tests. Comorbidities and obesity were prevalent among the entire cohort of participants (68.9% and 55.3%, respectively). Serum magnesium levels were significantly lower among individuals with comorbidities such as diabetes (0.78 ± 0.11 mmol/L vs. 0.84 ± 0.095 mmol/L; p = 0.008), whereas vitamin D levels showed no significant group differences. Persistent fatigue and muscle pain were associated with higher malnutrition risk scores (p = 0.019) and poorer adherence to recommended dietary intake mainly for cereals and fruits groups (p < 0.05). No significant associations were found between post-recovery persistent fatigue or muscle pain and serum vitamin D or magnesium levels. This study shows that malnutrition risk and a suboptimal diet persist long after COVID-19 recovery and are more strongly associated with post-viral fatigue and muscle pain than individual micronutrient deficiencies. Comprehensive nutritional rehabilitation, including dietary counselling and monitoring of key micronutrients, is essential for optimising recovery from long COVID.

Long COVID, Malnutrition, Diet quality, Vitamin D, Magnesium, Fatigue, Muscle pain, post-COVID rehabilitation