Healthy Food & Healthy Living by Dr. Ayala

Does a healthy diet reduce the risk of severe Covid-19?

I haven’t written about Covid for a while. Frankly, I was hoping to move on to other health topics by now – we’ve been living under this shadow for almost two years. But Covid-19 is still a central health matter, and many of its mysteries remain unsolved.

One of the most puzzling issues is the incredible variability in disease severity, age notwithstanding. Underlying medical conditions, such as hypertension and diabetes predict a higher likelihood of severe disease, as does obesity, but there’s a lot that can’t be explained by that.

Could nutrition inform some of this disparity? Poor diet is linked with the severity of other infectious diseases. Sound nutritional status supports immunity, lowers the chance of severe, out-of-control inflammation, and malnutrition causes immune deficiency.

This question remains relevant for this pandemic. Although vaccination is the most effective way to prevent severe disease and hospitalization, breakthrough infections are possible and ameliorating those is vital – we’re not completely done protecting ourselves, even with two shots. 

This question is also crucial for other infectious diseases known and yet to come.

Diet and the pandemic

A new study in the journal Gut looks at data from almost 600,000 people in the UK and the US, who were followed from March to December of 2020 by the smartphone based Covid-19 Symptom Study. All participants’ diet was assessed before the study began.

During follow-up almost 32,000 people had Covid-19 infections.

Healthy plant-based diets were associated with lower risk of contracting the disease and of severe Covid-19.

Poor diet quality was associated with lower socioeconomic status, as you might imagine. Healthy behaviors tend to cluster and people who eat healthy may sign on to other health-promoting measures. 

But the association remained strong even after accounting for other healthy behaviors, social determinants of health like education disparities, income inequality, housing insecurity, healthcare access, social isolation, food insecurity, unemployment, public safety etc., and the steps taken to prevent virus transmission such as mask wearing as well as the rates of transmission of Covid-19 in the community.  The authors conclude that: “The joint association of diet quality with socioeconomic deprivation was greater than the addition of the risks associated with each individual factor, suggesting that diet quality may play a direct influence in COVID-19 susceptibility and progression. Our findings suggest that public health interventions to improve nutrition and poor metabolic health and address social determinants of health may be important for reducing the burden of the pandemic.”

Another study of about 3000 health workers from France, Germany, Italy, Spain, UK, and the US showed that those on a plant based or pescatarian diet had lower odds of moderate to severe disease after taking into account other health characteristics, with the vegetarians among the group showing a 73 percent lower chance of moderate to severe illness, and the pescatarians with 59 percent lower odds of significant manifestations.

Again, removing every confounder is impossible, but we already have so many reasons to invest in healthy diets – personally with our own decisions and with public health interventions that increase access and education about the importance of eating well. This isn’t just the Covid-19 pandemic: Poor diets are a risk factor for a long list of chronic diseases, from heart disease to diabetes to cancer.

Dr. Ayala

Two thirds of kids’ calories come from highly processed food

Rates of childhood obesity have skyrocketed over the last decades, and there’s little doubt that the main culprit is our diet. Caloric intake has risen, as did the consumption of ultra-processed foods. Ultra processed foods make overeating incredibly easy: there’s very little you need to do in order to prepare them – they’re ready to eat or need a brief moment in the microwave or a little mix-in – they’re usually calorically dense, they provide lower satiety, and the flavors and mouthfeel are seductive. They’re also relatively inexpensive.

The more ultra-processed food in a society’s diet the greater the obesity rates. A recent large prospective study found a 10 percent increase in ultra-processed food was associated with a 10 percent increased risk in overall cancer and breast cancer rates. Another study following about 12,000 Americans with no underlying illness for more than 20 years found that consuming more ultra-processed food is associated with a 30 percent higher risk of dying.

A new study in JAMA looked at the diets of American kids and found that two thirds of calories now come from highly-processed foods. 

The study looked at a nationally representative sample of almost 34,000 2-19 year olds, and found that although sugary drinks intake decreased somewhat in the last two decades, those sugar calories were more than made up for by greater intake of bakery products and sweet snacks. Ultra processed food consumption increased especially among ethnic minorities, such as non-Hispanic Black kids, who are especially targeted for junk food marketing. Highly processed food use is rampant and pervasive in the entire population though, in all parental education levels and across all income levels.

What are the negatives of ultra processed foods? Most have low-quality carbs, coming from added sugar. Most are low in fiber. They contain additives, such as emulsifiers, stabilizers, preservatives and artificial sweeteners, which have been linked to unfavorable metabolic outcomes.

Beyond that, the authors note that: “processing itself may convey adverse health effects by changing the physical structure and chemical composition of food, which could elicit elevated glycemic response and reduced satiety.”

A recent study in the BMJ simulated what would happen if the use of ultra processed foods were to be reduced, and estimated that the prevalence of childhood overweight would go down from from 37 to 21 percent and obesity rates would move from from 20 to 11 percent. This study is just a simulation, extrapolating from a randomized controlled trial in which volunteers alternated between highly processed and less processed diets which were matched for total calories, energy density, carbs, protein and fat, fiber, sugars and salt and instructed to eat as much as they wanted. People on an ultra processed diet ate a daily average of 500 calories more than they did on an unprocessed diet.

But phasing out ultra-processed foods when they’re already a habit isn’t easy.

The Covid-19 pandemic brought about a return to home cooking for many families, but it seems like the rush to bakers’ yeast and kitchenware was temporary – people have reverted to ordering in and to ready-made foods. Childhood obesity rates, which we hoped had already leveled off, may be rising again during the pandemic.

Watching out for over-processed food

Think of ultra-processed foods as the polar opposite of whole foods, which should comprise the majority of what we eat. 

But cooking from scratch using whole foods isn't always practical, and let’s not over romanticize the era in which people spent all their waking hours preparing a meal – we do need someone else to do our food prep at least to a certain degree.

To enjoy the best of both worlds, when purchasing packaged food ignore marketing claims on the front of the label, and instead, read the ingredient list watching out for these indicators:

Artificial ingredients: 

If you can’t pronounce an ingredient, it’s probably a chemical, added for flavor, color, texture or preservation.

Lots of sugars/sweeteners:

Look at the “added sugar” quantity or look for sugars among the top three ingredients of non-dessert foods.  Watch out for sugar’s many versions, such as dextrose, evaporated cane juice etc. Foods with lots of added sugar are the embodiment of highly processed food, and the worst are sugary drinks. Desserts and treats are ordinarily made with plenty of sugar and sweeteners, whether they’re highly processed or made from scratch, and those are best eaten in moderation, regardless of processing level. High-fructose corn syrup is the embodiment of high processing and industrialized food.

Highly processed category until proven otherwise:

Fast food, most fully prepared and frozen meals, most mass produced chips, crackers, and highly sweetened cereals, cured meats (ham, salami, bacon, some sausages.)

What are your tips for minimizing highly processed foods?

Dr. Ayala