Research Review: a look at the role of over- and under-nutrition and flu risk, fatalities over the last 100 years

{This article was summarized even more, and added to my overall research notes, which can be read at www.playfullyfierce.com/covid19. I update it regularly with new notes from published reviews}

Many Americans, while possibly consuming too many calories – are malnourished when it comes to actual nutrients and nourishment, therefore potentially increasing their risk of contracting a virus.

Notes from the article Back to the Future: Lessons Learned From the 1918 Influenza Pandemic

Ironically, a study was done in 2018 entitled “Back to the Future: Lessons Learned From the 1918 Influenza Pandemic” and made this observation: “Since 1918, the world has experienced three additional influenza pandemics: the 1957 “Asian” influenza pandemic, the 1968 “Hong Kong” influenza pandemic and the 2009 so-called “swine flu” pandemic. These pandemics, although mild in comparison to that of 1918, highlight the constant threat that influenza virus poses to human health. Given that almost 100 years have passed since 1918, it behooves us to ask: are we truly better prepared for the next influenza virus pandemic or are there still lessons to be learned?

In civil practice, we are following many of the same steps they did: try to clean up hospitals, use face masks, shut down maritime trade, ban mass gatherings, close schools and dance halls and churches. And like them, efforts were varied around the world, and had varying levels of efficacy.

But what did they find about nutrition and the pandemic, that could potentially apply today?

The 1918 Influenza virus was reconstructed and used in lab studies. Like I have talked about with SARS-CoV-2 or Covid-19, the 1918 virus “triggered a potent, dysregulated pro-inflammatory response, which likely contributed to the severe lung lesions” as observed in victims of the 1918 influenza pandemic. So again, dysregulated inflammation was an issue. Additionally, this over-reacting immune response has also been observed in natural and experimental infections with both the highly pathogenic avian H5N1 virus (“Bird Flu”) and the 2009 pandemic influenza virus (“Swine Flu”)

The 1918 influenza pandemic had a fatality rate of >2.5%, “certainly higher than other influenza virus pandemics” as of 2018. But now in 2020, while Covid-19 fatality rates range because of inconsistent testing, it is estimated at roughly the same rate, if not higher, than the 2.5% of the 1918 influenza pandemic.

But the death rate range was vast from country to country. Death rates ranged from 2.5 people per 1000 people in Argentina, to 445 per 1000 people in Camaroon. This is likely due to a large array of variables, which this article explores.

In addition to exploring genetics, single-nucleotide polymorphisms (SNPs, or genetic mutations), quarantines imposed, and prior exposure to flu strains as variables, this article also looked at the correlation of host factors and lifestyle – which is what I will cover below. Yes, there are many variables, so isolating any one is difficult; and correlation is not always causation. But the points found with lifestyle were interesting and still seem to hold true with what we see in more recent years.

Many variables can play in to the body’s ability to avoid or fight off infection


Host nutritional status has long been recognized as an important factor in the outcome of a variety of different infectious diseases. In India in 1918, the effects of malnutrition and famine on influenza severity were particularly pronounced.

[to note, per the USDA, 11.1 percent (14.3 million) of U.S. households were food insecure at some time during 2018. The majority of Americans are not consuming the recommended amounts of fruit, vegetables, whole grains, or calcium-rich foods. And the 2015-2020 Dietary guidelines for Americans highlighted that much of the US population is under-consuming calcium, potassium, fiber, iron, Vitamins A, C, D, and E, choline, and magnesium.  In short – many Americans, while possibly consuming too many calories – are malnourished when it comes to actual nutrients and nourishment, therefore potentially increasing their risk of contracting a virus.]

“in any future influenza virus pandemic, we will face a “double burden” of malnutrition whereby a proportion of the world’s population will experience severe disease because of undernutrition and a proportion of the world’s population will experience severe disease because of overnutrition. Specifically, it is now well accepted that obesity increases one’s risk of being hospitalized with, and dying from, an influenza virus infection (Morgan et al., 2010; Louie et al., 2011; Van Kerkhove et al., 2011). Perhaps of even greater concern is the fact that obesity inhibits both virus-specific CD8+ T cell responses and antibody responses to the seasonal influenza vaccine (Sheridan et al., 2012). The challenge for future influenza pandemics is therefore not only to protect those affected by undernutrition (in particularly in light of the growing problem of climate change), but also the growing number of people living with obesity.”

What that means: undernutrition weakens the immune system due to lack of nutrients but also, “overnutrition” and obesity was also inhibited the immune system response, inhibiting the types of cells (CD8+ T cells and antibodies) that fight off the virus. Antibodies are specific to a vaccine or strain of flu; CD8+ T cells offer a more blanket-protection against the general flu virus.

Undernutrition is still reported as a problem for influenza pandemics of the twenty-first century and beyond.

“Despite the advances that we have made in pandemic preparedness over the last 100 years, there are also several new challenges that we face in the context of twenty-first century (and later) influenza pandemics. Today’s population demographic is dramatically different to that of 1918. Today, a large percentage of the world’s population is either elderly and/or living with one or more chronic medical conditions [such as heart disease, obesity, asthma, chronic obstructive pulmonary disease (COPD), and/or diabetes mellitus]. The number of immunosuppressed individuals (due to untreated HIV infection, transplantation or/and chemotherapy) is also increasing. This changing population demographic is of significance as each one of these host factors is known to increase the severity of even mild influenza virus infections.”

Take Away

In all of this, the 1918 flu had two waves – one in spring, and a stronger one in fall. Could the Covid-19 surge be the same, as global lockdowns begin “the hammer and the dance” with letting up, see a slight rise, lock down… let up, see a rise, lock down.. that could usher in another round? Whether or not that is our future in 2020, consider making some lifestyle changes and bolstering your immune systems now for whatever may come in the next 2 weeks or next 2 seasons.

There may not be much we can do about some of the variables in the previous illustration, but there is are some areas we do have some power to affect. Take control of your health, and protect yourself and your loved ones.

Check out the Next Level Health page for various programs to help you reduce inflammation, boost immune strength, and reach your health goals.


Main Journal Article:

Short KR, Kedzierska K and van deSandt CE (2018) Back to the Future: Lessons Learned From the 1918 Influenza Pandemic. Front. Cell. Infect. Microbiol. 8:343

Supplemental Research Sources:




Published by Kate Cline, RD

Registered Dietitian with a focus on Gut Health, Inflammation, and Functional Nutrition. Personal Trainer with a focus on corrective exercise. Yoga teacher, traveler, empowerment coach.

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