Newsletter #235

Hey friends! So, we are approaching the holiday season, which I’ve heard doctors refer to as the respiratory infection season. This year, I think that is especially apt, as we are facing a trifecta of COVID-19, RSV, and flu all at the same time.

One way to help dampen both transmission and severity of these illnesses, of course, is to get vaccinated. But we’ve known for some time that immune response to vaccines can vary quite a bit between individuals. How can you optimize your own body’s immunity in this situation?

One way would be to exercise. A new study, described below, found that frequent physical activity was linked to greater COVID-19 vaccine effectiveness (meaning lower risk of hospitalization due to the virus), and prior studies looking at the flu vaccine have found similar results.

Incidentally, the way that physical activity affects the immune system is fascinating. During exercise, blood levels of various immune cells can jump up dramatically. For instance, CD8+ T cells increase by approximately 2.5-fold, and natural killer cells skyrocket up to 10-fold. These immune cells are usually kind of hiding out in storage in the spleen and lymph nodes, but exercise pulls them out into circulation. However, shortly after exercise, something weird happens — the numbers of those immune cells in the blood drop down to even lower than before you worked out! What’s going on here?

Historically, it’s been thought that those immune cells must be undergoing programmed cell death, which would imply that your immune system was being suppressed (obviously not good). However, some very clever scientists decided to figure out what was actually happening to those immune cells by labeling them with fluorescent trackers and implanting them into mice, which were subsequently exercised on a treadmill. After exercising, the immune cells left the bloodstream, but they were not destroyed. Instead, they were redeployed to mucosal surfaces in the body, including the gut and the lungs. In other words, exercise causes your immune cells to be recruited and redistributed to parts of the body that are vulnerable to pathogens, in effect boosting immune surveillance. Pretty cool.

Previous research has shown that chronic physical activity improves immune responses to flu vaccination. To examine whether this also applies to COVID vaccination, researchers in South Africa looked at retrospective data from a large cohort of healthcare workers (n=196444). They referred to objectively measured physical activity records from wearable activity trackers, and split the participants into three categories based on levels of physical activity. They found that vaccine effectiveness against a COVID-9 related hospitalization was 60% for the low activity group, 72.1% for the moderate activity group, and 85.8% for the high activity group. Compared to individuals with low activity levels, vaccinated people with moderate and high activity levels had 1.4-times and 2.8-times lower risk of a COVID-19 hospital admission respectively. Exercise may strengthen the effects of vaccination by increasing concentrations of CD4 T cells (immune cells that help coordinate the immune response), boosting levels of salivary IgA immunoglobulin (antibodies in mucosal membranes that are in our first line of defense against infections), and by improving mitochondrial quality control.

Observational evidence suggests that olive oil plays a major role in the association between the traditional Mediterranean diet and lower incidence of chronic disease. However, not all olive oil is created equal. It is thought that virgin olive oil may be more beneficial due to its far higher concentrations of bioactive compounds, which are lost when olive oil is refined, and most epidemiological studies have failed to distinguish between varieties. To explore whether these varieties affect health outcomes differently, researchers in Spain analyzed data from a large nationally representative cohort (n=12161) who were followed for an average of 10.7 years. Subjects were split to three categories based on their use of virgin olive oil and “common” olive oil, the latter of which is more highly refined. The researchers found that regular moderate consumption of virgin olive oil (1.5 tablespoons daily) was linked to 34% lower all-cause mortality and 57% lower cardiovascular mortality, while the refined oil did not show these effects. There was also an interaction between virgin olive oil consumption and exercise — virgin olive oil use combined with high physical activity was linked to a 58% reduced risk of total mortality, when comparing the highest and lowest tertiles of consumption.

We have known for some time that muscle disuse reduces the ability of muscle to utilize amino acids from the diet to synthesize new proteins, which in turn leads to loss of muscle mass and function. This is obviously a particularly big problem for older adults, but it affects younger folks as well. For instance, when healthy young men were equipped with full leg casts for five days, muscle protein synthesis rates after eating were reduced by more than 50% in the immobilized leg. That’s obviously fairly extreme, but emerging research suggests that prolonged sedentary time, which is common in modern work and study, can also result in anabolic resistance. To investigate ways to counteract this process, researchers in Toronto recruited 12 healthy young participants and had them all go through three 7.5 hour long trials: 1) just sitting; 2) sitting with 2 minute walking breaks every half hour; and 3) sitting with 15 reps of bodyweight squats every half hour. The research team gave them liquid meals enriched with a phenylalanine tracer to assess protein synthesis. Both activity conditions resulted in moderate-to-large effect size benefits for the utilization of essential amino acids for synthesis of skeletal muscle proteins — comparable to the relative impact of structured resistance training on utilization of a single protein meal.

🐎 One of the greatest and most decorated war horses of all time was Staff Sergeant Reckless, a Marine pack horse during the Korean War.

During a single battle, she made 51 solo (unguided) trips to resupply the lines and bring back wounded men, and she was the first horse ever known to have participated in an amphibious landing.

Over the course of her service, she received two Purple Hearts and a battlefield promotion to sergeant.

Imagine being outranked by a horse 😳

Obviously, there are meaningful differences between extra virgin olive oil and more refined varieties. But even within the category of extra virgin olive oil, quality can vary considerably. Fortunately, there are easy-to-find, affordable options that have been proven to be the real deal. Trader Joe’s Premium Extra Virgin Olive Oil has been lab-tested and shown not only to be pure and unadulterated, but also exceptionally high in the aforementioned bioactive polyphenols. You can obviously get it at the store itself, or you can find it (like almost everything!) at Amazon.

Thanks for reading, enjoy the weekend, and we will see y'all next week!

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