Diet and Long Covid, five years on
Covid may be yesterday’s news and forgotten by some, but many are still affected. The last official data from the Office for National Statistics in March 2023, when there was testing for the Covid-19 virus, estimated that nearly 2 million people in the UK had Post Covid syndrome, or Long Covid. Recent estimates from self-reported data, now that there is no longer any Covid testing, suggest that Long Covid still affects over 1.5 million. The symptoms of Long Covid, defined as persisting longer than 3 months, are diverse, but overwhelmingly debilitating fatigue is common. Some with ongoing Long Covid are now being diagnosed with ME/CFS.
Whilst there has been some Long Covid research, many questions still need answers, especially since many individuals with Long Covid were not severely ill with the Covid-19 infection initially.
When it comes to nutrition and Covid-19, the situation is complex. So much is written online that is confusing and conflicting. Diet research is also fraught with difficulties. Study designs are often flawed, with unclear outcome measures or small sample sizes in the studies. This means that there is no high-quality evidence, and it is certainly insufficient to make recommendations on specific vitamins, minerals, or supplements for Long Covid. Quercetin, for example, is a flavonoid found in fruits and vegetables, which may decrease viral load. It can be taken as a supplement, but eating whole foods offers added benefits, including increased fibre and other nutrients.
There are two key theories to explain the ongoing symptoms of Long Covid. One is viral-, or spike- protein persistence. The second involves the immune system and inflammation in the body. Both may be in play to some extent.
1. What is an anti-inflammatory diet?
An anti-inflammatory diet is also known as the Mediterranean type diet. This best supports the immune system, which, when functioning correctly, regulates inflammation throughout the body. The body’s immune response is highly complex and involves the significant construction of new cells, including proteins and antibodies. This requires raw ingredients, such as protein, fats, and energy, as well as co-enzymes and various vitamins and minerals. To achieve this diversity of nutrients, the diet requires a wide variety of foods, including many colourful plant-based foods such as vegetables, fruits, nuts, pulses, seeds, and whole grains. Omega-3-rich foods, like oily fish or vegetarian alternatives, are recommended. This diet is low in highly processed, high-sugar, high-fat foods and snacks, and high in fibre. It is very similar to the recommended “Eatwell Guide”.
Maintaining good nutrition, ensuring your body has all the necessary nutrients and energy, is a crucial part of recovery from illness. For some, this may result in difficulty eating and significant weight loss. This depletes energy and nutrition stores, causing muscle loss and malnutrition, at a time when you need extra energy and nutrition to recover.
Malnutrition not only happens to those who are underweight, but also to potentially anyone who has had a severe or prolonged illness, which affects their ability to eat a varied, balanced diet.
2. Are you suffering from malnutrition?
Check if you are likely to be suffering from malnutrition, and work at improving this. Some highly rated self-screening tools are widely used by medical, health, and social professionals. One is the MUST tool. If you are concerned for yourself, or for a family member or friend, try the Patients’ Association Nutrition checklist.
Depending on the severity of your eating problem and weight loss, your doctor may refer you to a dietitian for additional support. Some people may need, and be prescribed, oral nutrition supplement drinks to achieve an adequate intake by their doctors.
3. Is the gut microbiome important?
There is emerging evidence about the importance of healthy gut bacteria for our health. The gut microbiome comprises trillions of bacteria that reside in our gut. The latest research suggests that they may play a far-reaching role in our physical and mental health. To improve our gut microbiome:
• Eat a wide range of different fruit, veg, pulses, beans, nuts and seeds
• Increase fibre intake (aim 30g per day)
• Aim for 30 different plant types a week over the full spectrum of colour
• Consider probiotics and prebiotics
• Include fermented foods, e.g. kefir, kombucha
4. What about histamine intolerance?
Histamine is produced by our body to fight off viruses and infections. It also occurs naturally in some foods.
The theory proposes that some people with Long Covid may have excess blood levels of histamine, triggered by the Covid-19 virus, and dysfunctional MAST cells (MAST Cell Activation syndrome). Histamine intolerance symptoms include headache, asthma, runny or blocked nose, low blood pressure, irregular heartbeat, hives, itching, diarrhoea, flushing and other conditions.
Symptoms can occur anywhere from a few hours to a few days after consuming foods high in histamine. These symptoms are similar to those reported by some people living with Long Covid. Some individuals have reported benefits from following a low-histamine diet, but the results are mixed. More research is needed.
Currently, there is no definitive test to diagnose histamine intolerance. It is not a food allergy; therefore, food allergy testing is not helpful. The best way to investigate histamine intolerance is to avoid high histamine foods for approximately 2-4 weeks, then to gradually reintroduce them to assess tolerance. This should be under the supervision of a registered dietitian, to ensure that it is followed safely and to minimise the risk of nutritional deficiencies.
It is also advisable to have a clinical assessment with a medical doctor. Ideally, one who is experienced in histamine intolerance (or Mast Cell Activation Syndrome). They can consider other tests to exclude other conditions.
5. How challenging is the low-histamine diet for sufferers?
Most people with Long Covid experience significant fatigue, making it very challenging to prepare and cook for a low-histamine diet, especially since fresh food is preferred over ready-made options. This diet also restricts some foods recommended for the gut microbiome. Therefore, for long-term health, it is essential to test tolerance to histamine-rich foods rather than avoid them altogether.
6. Why work with a dietitian?
A dietitian can assess your food diary and advise if you may benefit from a trial of a low-histamine diet. It is essential to work with a dietitian, as the low-histamine diet can be restrictive and may lead to nutrient deficiencies if followed for extended periods.
A dietitian will ensure adequate nutrition during the restriction phase and support when re-introducing foods. Some individuals may be able to tolerate a certain amount of histamine in their diet after a period of time.
7. Want to learn more about Nutrition and post-COVID recovery?
Visit the Health/Covid Knowledge Hub
It is hosted by the University of Plymouth, with funding from the British Dietetic Association. The information is for patients and professionals.
The BDA (British Dietetic Association) also has a helpful food facts information sheet on Diet and Long Covid
In summary, taking care of your nutrition and eating well will aid your recovery from post-COVID illness. The basis of a healthy diet for recovery is to include a wide variety of plant-rich foods, such as fruits, vegetables, pulses, beans, nuts, seeds, and a good intake of fibre, as well as regular Omega-3 foods. Most foods are best minimally processed, with reduced amounts of high-fat, high-sugar processed foods and snacks.
Written by Sue Luscombe, Associate Specialist Dietician & Nutrition Consultant