Chronic high fat and high sugar diet leads to worse COVID-19 outcomes

Posted on by Jesse Santiano, M.D.

A new preprint study showed that chronic high-saturated fat and high sugar diets resulted in worse COVID-19 outcomes among Syrian hamsters.

The study, Western diet increases COVID-19 disease severity in the Syrian hamster is from the National Institute of Health and National Institute of Allergy and Infectious Disease and was recently published in biorxiv.

 

Peach the Golden Hamster from Wikipedia

Why do we use Syrian hamsters for COVID-19 research?

As it turns out, the immune system of the Syrian hamsters has a lot of similarities with humans. Much research about the similarities in the immune system of humans and Syrian golden hamsters has been done since 2005.

Those similarities in human and hamster immune systems and their use in COVID-19 research were discussed in Syrian Hamster’s Starring Role in COVID-19 Research, and Syrian Hamster Unravels Inflammatory Insights in COVID-19.

Plus, it won’t be ethical to expose humans to the antigens of the SARS-CoV-2 experimentally. COVID-19 vaccines have already occupied that niche.

Peach the golden hamster. from Wikipedia

Back to the research. They fed  4-6 week old male hamsters with high fat, high sugar (HFHS) diet for 16 weeks ad libitum. The study hamsters gained weight faster. A control group was fed a regular diet (RD)

Results

  1. Impaired glucose tolerance was observed in the HFHS group. Impaired glucose tolerance results in higher blood sugars after a carbohydrate meal. This happens in people with diabetes.
  2. The total cholesterol was higher in the HFHS group.
  3. The alanine aminotransferase (ALT) is also higher. High ALTs are an indicator of liver injury. ALT is part of the Comprehensive Metabolic Profile (CMP) test commonly done in humans.
  4. The livers of the HFHS hamsters were grossly abnormal, showing signs of the fatty liver compared to the regular diet (RD) hamsters.
  5. Here is the most interesting part, 2,114 genes were significantly differentially expressed.
  6. This resulted in changes in 24 metabolic pathways and 200 downstream effects, resulting in increased inflammation, immune activation, and immune-associated pathways.

To illustrate the complexity of the genetic changes in fatty liver, look at the drawing below,

Source: Western diet increases COVID-19 disease severity in the Syrian hamster

And here is what the genetic changes will do to the immune system,

Source: Western diet increases COVID-19 disease severity in the Syrian hamster

Overall this translated into fatty liver disease and chronic inflammation of different organ systems.

This inflammation manifests as hypertension, coronary artery disease, arthritis, diabetes, and hyperactive immune response in humans to mention a few.

Next, they exposed the hamsters to SARS-CoV-2.

SARS-CoV-2 is the virus that causes COVID-19. Both regular diet (RD) and HFHS diet groups were exposed to the virus. In the RD group, the animals had mild to moderate disease.

Results in the High Fat High Sugar group

  1. Worse upper and lower respiratory COVID-19 infections.
  2. Increased total airway resistance and decreased inspiratory capacity translate into a decreased ability to breathe fully.
  3. The markers of inflammation, interleukin-6 and IL-10 levels were higher after infection.
  4. There is a more severe response in their serum lipids like free-polyunsaturated fatty acids (PUFA) and PUFA containing phosphatidylethanolamine. In humans, these lipid changes correlate with worse COVID-19 disease severity.

Take away message

  1. A long-standing high saturated fat and high sugar diet common in processed foods can lead to a fatty liver that leads to chronic inflammatory response and worse  COVID-19 outcomes.
  2. These findings are consistent with a worse clinical course of COVID-19 among obese individuals.
  3. People who are overweight and have fatty liver may benefit from intermittent fasting or time-restricted eating to resolve fatty liver disease and inflammation.

Knowledge about Covid-19 is rapidly evolving. Information may update as new studies are made. Stay current by subscribing. Feel free to share and like.

Don’t Get Sick!

Recommended readings

  1. The Effects of Three-Week Fasting in the Extremely Obese
  2. Intermittent Fasting while on Diabetes Medications
  3. The Effects of Intermittent Fasting on Asthma
  4. How to Do Intermittent Fasting
  5. The Kaizen Way of Fasting
  6. Early Time-Restricted Feeding is Intermittent Fasting In Sync with the Circadian Rhythm
  7. Will Fasting Make My Muscles Shrink?
  8. The Fasting Experience of 1422 Subjects at the Buchinger Wilhelmi Clinic
  9. Are You Skipping Breakfast?
  10. The 20/80 Rule for Health
  11. Autophagy – How to Recycle Yourself
  12. The Benefits of Intermittent Fasting and Fitness during Disasters

References:

  1. Munster et al. Western diet increase COVID-19 disease severity in the Syrian hamster. bioRxiv 2021.06.17.448814; doi: https://doi.org/10.1101/2021.06.17.448814
  2. Syrian Hamster’s Starring Role in COVID-19 Research

Image credits:

  1. Burger and fries: By ebru – Flickr, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=3252372
  2. Syrian golden hamster By TetraHydroCannabinol – Taken by TetraHydroCannabinol, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2049245

As an Amazon Associate, I earn from qualifying purchases.