When it Comes to Covid-19, Foods Choices Matter


As the long saga of Covid-19 continues, it is becoming apparent that the food we put into our mouths is an important key to winning the fight against this virus.



Until recently, data for the effects of food choices on the course of Covid-19 disease was lacking.  In November 2021, a prospective cohort study was conducted with the objective of examining the association of poor metabolic health and unhealthy lifestyle factors with the risk and severity of Covid-19.  The study obtained data from the almost 600,000 participants of the smartphone-based COVID-19 Symptom Study.  Diet Quality Scores, developed to evaluate the healthfulness of dietary patterns, are backed by evidence that dietary patterns capture the complexity of food intake much more thoroughly  than itemizing individual food items.  Using the healthful Plant-Based Diet Index (hPDI), a Diet Quality Score that emphasizes healthy plant foods such as fruits, vegetables and whole grains, the dietary content and quality of each study participant was assessed.  Results showed that, when compared with individuals eating the lowest quality diet, a high diet quality was associated with a 9% reduction in the risk of contracting Covid-19 at all and a 41% decrease in the risk of suffering from severe Covid-19.  This beneficial effect seems to be particularly relevant among individuals living in areas of socioeconomic deprivation.  These findings are in line with other investigations indicating that improving nutrition helps to reduce the burden of infectious diseases.  (1)


An investigation from June 2021 corroborates this information.  Healthcare workers with high exposure to Covid-19 patients from six countries were examined for their dietary habits and Covid-19 outcomes.  Those following a plant-based diet had a 73% lower chance of developing moderate to severe Covid-19 illness. However, those eating a low-carbohydrate, high-protein diet were 48% more likely to have moderate to severe Covid-19 illness (2).



Covid-19 sometimes presents as a syndrome, now known as “long-Covid”, in which symptoms remain long after the acute phase of the infection has gone.  Long-Covid can manifest in symptoms such as fatigue, headaches, cognitive disturbances, anxiety, depression, sleep disturbances, muscle weakness, joint pain, breathing difficulties and chest pain which may persist for weeks or months.  Plant-based diets have previously shown benefits for underlying conditions linked to poor Covid-19 outcomes, however, their role in long-Covid has been largely unstudied.  Pre-pandemic evidence suggested that a plant-based diet can lead to reduced inflammation and may be a strategy for tackling the systemic inflammation found in long-Covid sufferers.

A review from September 2021 sought to discover if eating plant-based could reduce the burden of long-Covid.   The following is a summary of the beneficial effects of plant-based diets outlined in this article for long-Covid sufferers.


Brain and Mental Health is Associated with Fruit and Vegetable Consumption:

People eating poor diets tend to be less healthy and happy than those eating a healthy diet.  Scientific study has revealed that, as daily servings of fruits and vegetables increase, so does life satisfaction and optimism.   Additionally, poor nutrition, identified by lower intake of fruits and vegetables and higher intake of meat and added sugars, is associated with higher rates of depression and anxiety.  Phytonutrients such as antioxidants and polyphenols, found only in plants, seem to play a significant part in the healthy effects of plants on brain health and cognition.  Phytonutrients increase blood flow to the brain, boost the production of energy in cells, are in involved with brain plasticity, and have demonstrated their ability to prevent or delay the onset of anxiety and depressio


Essential Fatty Acids and Risk of Death From Covid-19:

Essential fatty acids are those that cannot be produced by the body and therefore must be obtained from food sources.  They include both omega-6 and omega-3 fatty acids.  Omega-6 fatty acids are generally inflammatory; omega-3 are anti-inflammatory and are involved in the modulation of the immune system.  The ratio of intake of these two types of fatty acids dictates their future.  Both are converted in the body to a more active long-chain form, omega-6 to arachidonic acid (AA) and omega-3 to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).  This conversion is accomplished by enzymes.  However, omega-3 and omega-6 fatty acids must compete for the same enzymes.  If one fatty acid type is present in much higher amounts than the other, it will commandeer the enzymes and the other type will not be appreciably converted.  Ideal ratios of omega-6:omega-3 fatty acids are between 1:1 and 4:1.  Unfortunately, over the past few decades, intake of processed and animal-sourced foods have strikingly increased, raising the omega-6:omega-3 ratio in the standard Western diet as high as 15:1 and sometimes even above 20:1.  Such dietary patterns are pro-inflammatory and are associated with depression in both adults and children. Lower omega-6:omega-3 ratios can be achieved by eating mostly plants and limiting isolated oils from the diet. (4)

Lower omega-6:omega-3 ratios are also associated with a lower risk of death from Covid-19 as well as with improvements in respiratory and kidney function in critically ill Covid-19 patients. In addition, omega-3 fatty acids have been found to strengthen psychological resilience during the Covid-19 pandemic.

NOTE:  Although long chain omega-3 fatty acids (EPA and DHA) can be obtained through eating fish, studies have found that a fish-free diet may be better for mood improvement.  It is thought that this is due to the saturated fatty acids, cholesterol and the omega-6 fatty acid, arachidonic acid (AA) derived from eating fish and other animal-sourced foods.  From AA, pro-inflammatory substances such as leukotrienes and prostaglandins are produced which have been repeatedly associated with adverse effects on brain neurotransmitters and increased anxiety.  It is postulated that higher dietary intake of fish-derived long-chain omega-3 fatty acids is unable to compensate for the harmful inflammation caused by AA.  In a situation where EPA and DHA are suspected to be low, a good source of these long chain fatty acids would be a supplement derived from algae-sourced EPA and DHA.


Plant-Based Diets Encourage the Availability of Tryptophan for the Brain:

Several studies have identified substantial alterations in the metabolism of the amino acid tryptophan in Covid-19 patients.  Tryptophan controls the synthesis of the neurotransmitter serotonin in the brain which plays an important role in the development of depression.  Diets higher in tryptophan seem to protect against depression and anxiety.  Experts speculate that Covid-19-related alteration in both tryptophan absorption and metabolism could be the underlying pathophysiology of long-Covid symptoms.  Carbohydrate-rich meals increase the absorption of tryptophan into the brain while protein-rich meals have the opposite effect.  Eating mainly plant-based means eating a diet high in the complex, unrefined carbohydrates found in fruits, vegetables and legumes that encourage the transport of tryptophan past the blood-brain barrier and into the brain.


Plant-Based Diets Encourage Better Sleep Quality and Less Stress:

A tryptophan-rich dietary pattern has also been shown to improve quality of sleep. The Covid-19 pandemic is a widely recognized risk factor for sleep disorders.  Several studies have suggested that plant-based diets high in fruits and vegetables can improve sleep quality.  On the other hand, low-fiber and high saturated fat diets are associated with lighter, less-restorative sleep.  This may be because plant-based diets avoid foods linked to impaired sleep duration and quality (meat, high-fat products) and are abundant in magnesium-rich foods which are associated with improvements in sleep quality, length of sleep and time to onset of sleep.  High magnesium intake is also associated with lower risk of mental and physical stress, both very common effects during the Covid-19 pandemic.


Plant-Based Diets Lower Musculoskeletal Pain:

Many long-Covid patients report persistent muscle and joint pain.  Such pain has been linked to diets high in animal protein, fat and sugar and low in fruit and fiber.  Low intake of magnesium and folic acid are also associated with chronic muscle pain.  Plant-based diets are abundant in fiber, magnesium and folic acid and, in addition, they restrict animal products with their saturated fatty acids and pro-inflammatory effects. Studies consistently show lowered levels of inflammation in plant-based eaters and so it comes as no surprise that plant-based diets are associated with lowering of musculoskeletal pain and increased joint function.  In patients with long-Covid, inflammatory pathways can remain active for up to 60 days after the infection.  Adopting a plant-based diet is one strategy that can tackle this prolonged systemic inflammation.


Plant-Based Diets Improve the Immune Response: 

Eating plants is a known way to reduce inflammation and benefit immune function.  In fact, plant-based diets are linked to lower risk of developing moderate-to-severe Covid-19 disease.  It is thought that the richness of nutrients such as antioxidants, phytosterols, polyphenols and vitamins found in plants are the cause of this benefit.



Plant-based diets are an effective way to lose excess weight.  An article in the July 2020 edition of the BMJ noted that the science of medicine has finally begun to acknowledge that dietary choices and being overweight or obese are not only linked to chronic conditions such as diabetes, cardiovascular disease, cancer and depression, but are also surfacing as key risk factors for Covid-19.  A consensus is emerging that embracing diets richer in whole foods (including grains, vegetables, fruits and legumes) and low or void in red meat, refined carbohydrates and processed foods is imperative for the collective health of the human species.   Unfortunately, current national guidelines fall far short in this endeavour.



The dire consequences of the widespread consumption of meat go far beyond the direct harms from eating the meat and they need to be recognized.  This is especially true of the impacts of the meat industry on the severity of Covid-19 disease.  Meat processing facilities have materialized as incubators for the disease and have been linked to covid outbreaks in the US since very early in the pandemic.  Slaughterhouses and meat processing plants provide very favourable environments for covid-19 transmission.  Their lower temperatures and high humidity present ideal conditions under which the SARS-CoV-2 virus, the virus that causes Covid-19, can thrive.  Circumstances on the meat assembly line promote the production of aerosols that can contain dust, feathers/fur and feces along with Covid-19 virus emitted from affected workers.  These tiny particles are then spread extensively through the intense use of water.  Metallic surfaces, though easier to clean, allow viruses to survive longer outside a body.  Additionally, workers are obliged to work in cramped conditions and are unable to physically distance.  They are forced to speak loudly or shout to be heard over the noise, increasing the production of aerosols that can carry the virus to others. Under these conditions, Covid-19 is nurtured, spreading quickly among workers and then carried outside to the surrounding communities where the plant employees live.  This grave situation has been documented around the world in places such as Brazil, Germany, France, Spain, Canada, the US and the UK.

Increasingly, calls are being made for the meat industry to accept responsibility for their part in the spread of Covid-19.  Prevention measures to inhibit future outbreaks need to be implemented.  Some suggested changes include staggering start, finish and break times; installing barriers between workers on production lines; reducing the processing rate of the meat; mandating face coverings; introducing enhanced cleaning and disinfection processes; screening workers for symptoms; encouraging workers to stay home if they are ill; and providing adequate sick pay.



The effects of the food we choose to eat on Covid-19 disease are no longer unknown.  Plant-based eating patterns have revealed their ability to protect us from the full force of the SARS-CoV-2 coronavirus both in its acute phase of infection and from its potential long-term effects.  Best of all, with a bit of planning and determination, nutritional improvements can be adopted by any individual who is looking for a way to fight back against this alarming disease.



1  Merino, J., Joshi, A.D., Nguyen, L.H., Leeming, E.R., Mazidi, M., Drew, D.A. et al.  Diet quality and risk and severity of Covid-19: a prospective cohort study.  Gut. 2021 Nov; 70(11):2096-2104. Doi:10.1136/gutjnl-2021-325353.

2  Kim, H., Rebholz, C.M., Hegde, S., et al. Plant-based diets, pescatarian diets and COVID-19 severity: a population-based case–control study in six countries. BMJ Nutr Prev Health. 2021 June 7; 4(1): 257-266.  Doi: 10.1136/bmjnph-2021-000272.

3  Storz, M.A. Lifestyle Adjustments in Long-COVID Management: Potential Benefits of Plant-Based Diets. Curr Nutr Rep. 2021; 10: 352–363  Doi.org/10.1007/s13668-021-00369-x.

4  Simopoulos, A.P., The Importance of the Ratio of Omega-6/Omega-3 Essential Fatty Acids.  Biomed Pharmacother. 2002 Oct ;56(8): 365-379. Doi: 10.1016/s0753-3322(02)00253-6.

5  Godless, F.  Covid-19: What we eat matters all the more now.  BMJ 2020 July 16; 370.  Doi:https://doi.org/10.1136/bmj.m2840.

6  Middleton, J., Reintjes, R., Lopes, H.  Meat plants—a new front line in the covid-19 pandemic.  BMJ. July 9, 2020; 370.  Doi:https://doi.org/10.1136/bmj.m2716.









Promoting a healthy adventurous lifestyle powered by plants and the strength of scientific evidence.

My name is Debra Harley (BScPhm) and I welcome you to my retirement project, this website. Over the course of a life many lessons are learned, altering deeply-rooted ideas and creating new passions.

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