Our research shows that eating a plant-rich diet helps protect us against COVID-19. But what should we be eating when we’re ill with it or suffering from long COVID?

When feeling rubbish, you’re less likely to eat normally and get the nutrients you need. COVID-19 can make eating even harder as it affects taste and smell and can leave people with a reduced appetite.

We’re still learning about COVID-19, but in some ways it’s similar to other respiratory illnesses, and there’s evidence that what you eat can help you feel better as you recover and even speed up the healing process.

Which nutrients support the immune system?

We know from our nutrition research that eating more plants is better for keeping your gut microbiome and immune system healthy.

A number of vitamins (A, B6, B12, C, folate and E) and trace elements (zinc, copper, selenium and iron) are known to play an important part in supporting the immune system. These are best sourced from a diverse diet, including:

• Milk and cheese – source of vitamin A and B12
• Fish and oily fish – source of vitamins A, B6 and B12 and Selenium
• Green leafy vegetables such as kale, spinach and broccoli – source of vitamins A and B6, folate and iron
• Nuts and seeds – source of vitamin E, copper and iron
• Meat – source of zinc, iron, selenium and vitamins B6 and B12
• Fruits – source of vitamin A and C

Vitamin D also plays a role in the immune system and low levels have been associated with an increased risk of infection and respiratory diseases. But, as Professor Tim Spector and Dr John Campbell discussed in this conversation, we still need more evidence to show whether vitamin D can protect against COVID-19.

What should I eat when I’ve got COVID-19?

When you’re ill, it’s important to try and eat foods containing enough energy (calories) to support your recovery, as well as protein to help maintain your weight and muscles, especially for people who are hospitalised with COVID.

If you’re feeling ill with COVID-19, try protein-rich foods such as meat, eggs, fish and full fat dairy or plant-based alternatives like pulses, legumes, nuts and seeds. You can boost your calorie intake by snacking more often and adding extra ingredients to meals. For example, mashed potatoes, cheese or avocado to omelettes, beans on toast, or adding nuts or nut butter to porridge and sauces.

If you don’t feel like eating you could try sipping water or high calorie drinks throughout the day, smoothies or hot drinks made with whole milk. This will help you stay hydrated, too.

Our bodies also need more vitamin C and zinc when fighting a respiratory illness like COVID-19. Vitamin C is found in oranges and orange juice, red and green peppers and strawberries while zinc is in shellfish, meat and cheese.

Do low histamine diets help recovery from long COVID?

There are a number of diets and eating patterns popular within the long COVID community. One is to follow a low histamine diet, which is supposed to reduce the ongoing inflammation that is thought to be a key cause of long COVID symptoms.

While our nutrition research shows that certain eating patterns are linked to inflammation, there isn’t strong evidence showing that low histamine diets can combat inflammation in long COVID. But in the absence of robust studies about the best nutrition for long COVID, it’s understandable that people might want to give it a try.

Registered dietitian Elaine Anderson has written about low histamine diets for long COVID and warns:

“A low histamine diet can be restrictive and time-consuming. Feedback from the long COVID support groups suggest that many have tried the diet but found it difficult to follow combined with their debilitating symptoms. There are also many food lists available on the internet and many have conflicting advice.”

Do supplements help recovery from long COVID?

Another popular idea within the long COVID community is a high dose vitamin stack of niacin (vitamin B3), vitamin C, vitamin D, quercetin and zinc. Some people feel it works for them, but we don’t yet have robust scientific studies to show whether these supplements really help.

While we still don’t know which eating patterns or foods can help relieve the symptoms of long COVID, it’s worth taking time to think about what you’re eating and finding what works for you. At the same time, it’s important to think about your diet holistically so you don’t accidentally end up restricting what you eat too much, which can harm your health in the long term.

Where can I get advice on nutrition and long COVID?

Talk to a registered dietitian for advice on how best to eat to help your health if you have long COVID. You can be referred to an NHS dietitian by your GP or find one privately.