For many people, particularly following vaccination, infection with SARS-CoV-2, the virus that causes COVID-19, resolves within a few days. But for others, it results in long COVID, a variety of often debilitating symptoms that persist for weeks, months or even years. Why this happens in some is unclear, and there are currently no effective treatments. Some experts believe diet could be key to symptom management. What is the evidence for this?

Researchers describe long COVIDTrusted Source — also known as post-COVID-19 condition — as “an often debilitating illness,” noting that it “occurs in at least 10%” of people who have had COVID-19.

It can result in a wide range of symptomsTrusted Source, which, according to the Centers for Disease Control and Prevention (CDC), may include:

• tiredness or fatigue that interferes with daily life
• fever
• difficulty breathing, cough or shortness of breath
• chest pain and heart palpitations
• difficulty thinking or concentrating, also referred to as “brain fog”
• headache
• sleep problems
• dizziness when standing up
• pins-and-needles feelings in limbs
• change in smell or taste
• depression or anxiety
• diarrhea
• stomach pain
• joint or muscle pain
• skin rashes
• changes in menstrual cycles.

Why some people develop long COVID is not entirely clear, but factors that increase the likelihoodTrusted Source include older age, being female, having other chronic conditions, and having had severe COVID-19.

Studies have shown that vaccination and early treatment with antiviralsTrusted Source may decrease the likelihood of developing long COVID. A nonpeer-reviewed preprint has suggested that treatment with convalescent plasmaTrusted Source could do the same.

So what might be some of the underlying mechanisms in long COVID, and could achievable interventions, such as following a specific diet, help manage its symptoms. Medical News Today looked at the existing evidence, and spoke to experts to find out more.

Dr. Adupa Rao, a medical director at the Keck Medicine Covid Recovery Clinic, told MNT that “there is no clear signal why certain people develop long COVID.“

However, according to him, a misfiring immune system, triggered by SARS-CoV-2, may prolong the state of illness indefinitely for some people.

“We suspect that the underlying problem is that the immune system gets activated after COVID infection and stays on after the infection has resolved,” said Dr. Rao.

“The continuous activation of the immune system means that the body is very active seeking to fight infection and is in the high-inflammatory state,” he explained.

Prof. Arturo Casadevall, chair of Molecular Microbiology & Immunology at Johns Hopkins Bloomberg School of Public Health, agreed, noting that “the inflammatory nature of long COVID is an increasingly accepted fact although it is important to keep in mind that we have known this disease for only 3 years.”

Treatments similar to those for other post-viral syndromes, such as chronic fatigue/myalgic encephalomyelitisTrusted Source, may be beneficial. These include getting plenty of rest and doing gentle, but not vigorous, exercise.

A 2017 meta-analysisTrusted Source of dietary intervention for post-viral syndromes found that supplements and long-term elimination diets were generally not beneficial.

The study’s conclusion was that a balanced diet and a variety of nutritious foods were most likely to help with symptoms.

Kelsey Costa, a registered dietitian nutritionist with National Coalition on Healthcare (NCHC), agreed, telling MNT that, “in managing post-viral conditions like chronic fatigue syndrome, a nutritious, balanced diet can enhance body functionality, improving well-being.”

“While diet alone is not a cure for post-viral conditions like chronic fatigue syndrome, it can play an essential role in managing symptoms and supporting overall health and well-being,” she added.

Although studies Trusted Sourcehave identified ways to reduce the likelihood of developing long COVID, there are, as yet, according to a wide-ranging reviewTrusted Source “no broadly effective treatments.”

This review highlighted treatments that are effective for some of the symptoms, such as low-dose naltrexoneTrusted Source for pain, fatigue and neurological symptoms, low-dose aripiprazoleTrusted Source for fatigue, unrefreshing sleep and brain fog, and probiotics for gastrointestinal symptoms.

It also emphasized that exercise was not advisable, recommending instead pacingTrusted Source “an active self-management strategy whereby individuals learn to balance time spent on activity and rest for the purpose of achieving increased function and participation in meaningful activities”.

No therapy, however, is effective in isolation, and lifestyle changes to treat the symptoms are generally preferable to medication which may have side effects, so experts suggest that a dietary approach could give relief to some.

Several diets have been considered as potential treatments for long COVID, and evidence is building that some may be beneficial while others are less effective.

They include vegetarian and vegan diets, anti-inflammatory diets, and antihistamine use and so far, the evidence appears to suggest that anti-inflammatory diets may have the greatest beneficial effect.

“By reducing the intake of pro-inflammatory mediators and increasing the consumption of anti-inflammatory foods, adopting a plant-based diet could be an easily accessible strategy to combat the prolonged systemic inflammation often seen in long COVID patients,” she told us.

One diet proven to have health benefits is the Mediterranean dietTrusted Source, and Costa advocated this for people with long COVID, noting that “the Mediterranean diet, a consistently recommended dietary choice, is characterized by its richness in bioactive compounds, such as monounsaturated fats, omega-3 fatty acids, vitamins, minerals, and phytochemicals.”

“These compounds have demonstrated anti-inflammatory and antioxidant activities, providing a powerful tool against diseases associated with long-term, low-level inflammation,” she added.

With evidence building that inflammation might be responsible for many of the symptoms of long COVID, scientists from Keck Medicine at the University of Southern California, are running the first controlled trial of an anti-inflammatory diet to treat long COVID.

The 50 participants in the 30-day dietary trial will be divided into two groups. One will eat a low-carbohydrate diet to lower blood glucose (sugar) levels in combination with a medical food that raises blood ketone level. The other group will have no dietary intervention.

A study in ratsTrusted Source linked a ketogenic diet with reduced oxidative stress and inflammation. And a reviewTrusted Source has animal studies linking the diet with reduced neuroinflammation.

Costa welcomed the study, saying that its “exploration of a low-carbohydrate diet and medical food to elevate blood ketone levels could potentially offer a novel approach to managing long COVID-19 symptoms.”

“By transitioning the body’s metabolic state to a fat-dependent ketogenic state, this intervention may reduce inflammatory responses, enhance antioxidant defenses, and improve DNA repair mechanisms,” she added.

Throughout the trial and at the end of the 30 days, the researchers will test inflammatory markers in both groups, assess how well the intervention group is tolerating the diet and check long COVID symptoms in both groups. If the diet group shows positive effects, they will expand the clinical trial to a larger population.

“We chose 30 days as the intervention, because we believe that we will start to see a signal in the inflammatory state in that period of time and we will be able to monitor the safety of effects of the nutritional supplement,” Dr. Rao explained