A clinical definition of long COVID has been released by the World Health Organization (WHO) (2021) in response to a global surge in patients suffering with long COVID, where symptoms are continuing 3 months and beyond. Long COVID can occur in anyone who has contracted the SARS-CoV-2 virus, irrespective of age and severity of COVID-19 illness. Up to 3 in 10 post-COVID-19 patients are suffering with long COVID symptoms, which are reported to include fatigue, poor memory and concentration, smell and taste impairment, and lack of appetite. To date, the exact mechanisms responsible for persistent symptoms of long COVID are not known.
Studies have had more emphasis on dietary and lifestyle habits associated with post-viral persisting inflammation. Dietary and lifestyle factors could have implications such as prolonging symptoms or preventing the ability to return to full health. Loss of smell and taste was common in COVID patients, and now commonly occurs in post-COVID patients. A survey led by the Royal College of General Practitioners (2020) found that more than half of UK GPs surveyed had patients who reported taste and smell disorders after 3 months. A group of international scientists surveyed around 1500 participants with co-impaired smell and taste at COVID onset and followed up their symptom and recovery at a median of 200 days since the illness onset (Ohla et al, 2021). The findings revealed that about two-thirds of participants had persistent symptoms at the 200-day follow-up point. The recovery of smell was less likely to occur than that of taste. Individuals with persistently altered smell were also more likely to have taste disorder and other long COVID symptoms including headache, fatigue and lack of appetite.
Smell and taste dysfunction affects 20% of people aged 60 and over in the UK but is often overlooked by primary care providers (Philpott, 2014). As is the case with long COVID, a qualitative study led by university researchers in the UK revealed that health professionals, families and patients seemed to underrate the importance of smell and taste compared to physical and psychological wellbeing (Burges Watson et al, 2021). Moreover, patients could not explain with confidence to their health practitioner exactly how they experienced impaired smell and taste. Thus, patients felt a lack of empathy and support from others. Notably, post-COVID patients with altered smell and taste found their day-to-day life, particularly eating, difficult and distressing (Burges Watson et al, 2021). Lingering smell or taste impairment could have drawbacks for food preferences and diet quality. It also diminished their pleasure in social relationships associated with eating. Weight loss and malnutrition were common experiences of patients in the study, although they considered these to be insignificant.
In addition, dysfunctional sensory perceptions are associated with mental health issues such as fear, anxiety and low mood. Poor mental health may also place post-COVID patients at higher risk of malnutrition, and vice versa. Approximately 30% of post-viral people in the UK suffered mental health problems including anxiety and depression up to 6 months after COVID-19 infection. The correlation between nutritional and inflammatory status of post-COVID patients and psychiatric disorders remains unclear, but knowledge gleaned from other chronic conditions shows that mental ill health sufferers are likely to be malnourished and display inflammation. Post-COVID health sequelae or public health measures, including national lockdowns and quarantine, could increase physical inactivity and sedentary behaviour. Prolonged COVID symptoms also impede physical activity up to 6 months after COVID onset. Physical activity has important benefits for mental health, physical fitness, weight management and the prevention of many chronic diseases.
Nutritional therapy strategy
Nurses, who work in a variety of settings ranging from clinics to home, play an important role in monitoring the risk of malnutrition among post-COVID patients, as well as being on the front line of educating patients, their families and carers about nutrition and diet. Using a scoring system for risk assessment of malnutrition of an individual, it is important to recognise smell or taste disorders, mental health issues and physical inactivity that could trigger the process of malnutrition and inflammation. In terms of a nutritional therapy strategy for long COVID patients, there are three points to take into account.
First, a plant-based diet is well-established to lower inflammatory effects. Long-COVID symptoms such as fatigue, insomnia, and musculoskeletal pain can be improved with a plant-based diet (Storz, 2021). Moreover, it also provides plenty of vitamins, phytochemicals and antioxidants to support the immune system. A plant-based, high-fibre diet appears to be beneficial to host gut microbiomes to enhance the immune system. A plant-based diet has a variety of protein-rich sources (eg pulses, beans, tofu, nuts and seeds) and healthy fats (eg olive oil, avocado). Furthermore, adherence to a ‘plant-based’ diet does not necessarily eliminate animal-derived foods. Consuming animal foods such as eggs and oily fish can add benefits of essential amino acids and omega-3 DHA and EPA. You can encourage your patients to follow the steps below to smoothly and naturally transition to a plant-based or plant-dominant diet:
- Use a plate to provide examples of recommended portions of plant-based foods, which can be shown as half to two-thirds of the plate
- Follow the national guidelines for consuming at least five portions of a variety of fruits and vegetables per day. One portion is around 80 g. Frozen, fresh or canned fruits and vegetables all count towards the total 5-a-day. Remember to advise consuming an array of colourful fruit and vegetables
- Eat at least 30 g of fibre every day. Non-starchy vegetables, whole grains and pulses mostly containing dietary fibres. You can show your patient a handout with a list of common foods containing fibre
- Gradually switch to sources of healthy fat such as oily fish, olives, nuts and seeds, as well as occasionally consuming high-protein sources including mushroom, tofu or beans instead of processed meats.
Second, studies show that post-COVID patients did not feel hungry before meals. Moreover, their satiation signals were likely to occur faster during the meals than before the pandemic (Høier et al, 2021). Hunger and satiation cues working together efficiently during a meal is associated with palatable food experiences driven by sensory perception. Having the five sensory systems working together during a meal is important to appreciate the palatability of the food consumed. When it comes to dysfunctional sensory perception among COVID patients, the palatable state of food is diminishing. As mentioned earlier, this can result in dysfunctional appetite, malnourishment, and mental implications, which could trigger prolonged symptoms of long COVID. Notably, mindful eating could help connect an individual to their hunger and satiation cues during a meal, although scientists are still examining these methods in COVID long-haulers. According to the fundamental philosophy of mindful eating, consumers become more attentive to the cross-interactions of all senses associated with eating without any judgements, which improve an ability to recognise hunger and satiate feelings.
Post-viral patients and their families should be cared for with attention and sympathy to recognise how conscious or subconscious their decisions are when eating. You can encourage your patients to use the ‘I do’ method to practice during each and every moment of eating. They do not necessarily need to implement all of the steps at once, but gradually implement each ‘I do’ where appropriate.
- I do make a shopping list
- I do choose or prepare ingredients for meals
- I do have a meal while sitting at a table
- I do have my meal without distractions (such as using the phone or watching TV)
- I do not skip any meals
- I do stay mindful of my senses while eating. For example, eating an apple. While holding the apple, the person takes a while to look at and touch it. At the time, they can connect all of the links to the apple such as its colour. This helps gain an insight into what they are eating, which is typically overlooked in mindless eating. Then they take a small bite and chew it slowly. They can hear the sound of the broken apple piece and feel how it moves around in their mouth, incorporating as many senses as possible. Adherence to this approach for at least one meal a day is a practical introduction to this method.
Third, dietary supplements are not considered substitutes for adequate dietary intake through diet. However, they can offer additional benefits for individuals whose diet is insufficient in essential nutrients the body needs. Vitamin supplements may be particularly beneficial for the intake of vitamin C and D. Vitamin C deficiency for 3 months can cause scurvy, and there has recently been an increase in hospitalised cases in NHS settings. Getting enough vitamin D is important to maintain bone health and overall health. Vitamin D deficiency in the UK adult and child populations is evident. A recent analysis of nearly 500 000 UK biobank accounts highlighted that there was a great disparity in vitamin D deficiency between different ethnic and socioeconomic groups in the UK. The findings revealed that Asians in the UK had the highest risk of vitamin-D deficiency during winters and summers (Joshua et al, 2020). Alongside vitamin C and vitamin D, micronutrients such as zinc and magnesium are essential nutrients for the immune system. Probiotics with strains such as Lactobacillus casei, L reuteri or Bifidobacterium have been clinically proven to balance host gut dysbiosis following an infection, but the effect on post-COVID gut imbalance is still being investigated. Balanced gut microbiota is important for the development of a healthy immune system as around 70% of immune cells are located in the gut. Thus, vitamins and dietary supplements appear to be advantageous for people in whom deficiency is suspected or confirmed. Studies show that COVID long-haulers might have a high risk of malnutrition and nutrient deficiency. It is necessary to have a discussion with a specialist in nutrition if nutrient deficiency risk is high or accompanied by medical complications.
Conclusion
Proper nutrition in the road to recovery of COVID is essential; however, different aspects could affect the process. Increased mental distress and physical inactivity, and persistently dysfunctional smell and taste among post-viral patients should not be underrated as these clues can provide insight into various forms of malnutrition. A plant-based diet would be advantageous to provide plenty of vitamins, antioxidants and dietary fibres, and mindful eating could wake up hunger and satiation cues. Vitamins and dietary supplements are important for those with long COVID to maintain overall health and prevent nutrient deficiency.
KEY POINTS
- Factors including malnutrition, physical inactivity and mental ill health can contribute to prolonged COVID symptoms
- Smell and taste dysfunction is common in those with long COVID, but it could be underrated or overlooked
- A plant-based diet might help to lower the hyper-inflammatory process, while ensuring the body gets all the nutrients it needs
- Mindful eating could connect the individual to the body's hunger and satiety signals to improve appetite and food intake
- Supplementing essential nutrients including vitamin D, vitamin C, zinc, magnesium and probiotics might support overall health for long-haulers