Newsletter #011

Hello friends, and welcome to the latest HumanOS newsletter! We hope you are having a lovely and healthy summer so far. Here we highlight our work, as well as some research and media that we find useful and interesting.

This week, Dan interviewed Susan Westfall about her work using a novel synbiotic (probiotics plus prebiotic) to modulate the gut microbiota of fruit flies over the course of their lives. This formulation, which incorporated the Ayurvedic herbal concoction Triphala, elicited a range of interesting biological effects in the experimental group. It reduced oxidative stress, inflammation, insulin resistance, and other markers that typically contribute to poor health later in life, in insects and humans alike. But most remarkably, the fruit flies consuming the synbiotic lived a whopping 60% longer than controls!

Research like this adds to a pile of evidence suggesting that cultivating (and feeding) the right microorganisms in our gut could have profound effects on our health and longevity. And we are working on some things which will hopefully provide some guidance on how to do just that, so stay tuned. In the meantime, combining some fermented foods and polyphenol-rich plants seems like a solid idea to me.

As women go through menopause, their hormone levels change and their bones can become weaker. This can lead to a higher risk of fractures and other bone-related problems. However, certain foods may help prevent bone loss and maintain bone health. In a study of 482 postmenopausal women, researchers found that those who regularly ate fermented dairy products like yogurt had less bone loss in certain areas than women who consumed milk or cheese. The study assessed the women's diets and bone health over a period of three years. The researchers used scans to measure the bone mineral density and microstructure of the women's bones. They found that fermented dairy products consumers had lower abdominal fat mass and larger bone size at the start of the study. Moreover, fermented dairy products consumption was associated with attenuated bone loss in certain areas of the body, such as the radius and tibia. However, there was no difference in bone mineral density at the tibia, and other dairy products like milk or cheese did not have the same effect on bone health as fermented dairy products. These associations were independent of total energy, calcium, or protein intakes, meaning that consuming fermented dairy products, such as yogurt, may help reduce age-related bone loss in postmenopausal women regardless of their other dietary habits. Therefore, adding yogurt to your diet could be a simple and tasty way to improve your bone health and reduce the risk of fractures as you age.

This study examined 829 teenagers and used wrist actigraphy to measure sleep duration, efficiency, and moderate-to-vigorous physical activity for over five days, recording for more than ten hours per day. The sample was about half girls and half boyws, and the mean age was about 13 years old. Longer sleep duration was associated with lower metabolic risk scores. Associations with sleep efficiency were similar and persisted after adjustment for BMI and physical activity, television-viewing, and diet quality. Longer sleep duration and greater sleep efficiency were also favorably associated with waist circumference, systolic blood pressure, high-density lipoprotein cholesterol, and fat mass.

Researchers performed a systematic review of prospective cohort studies that evaluated the association between cardiorespiratory fitness and the development of depression. Cardiorespiratory fitness is a measure of how well the heart, lungs, and muscles work together during physical activity, and it is often assessed by measuring maximal oxygen uptake (VO2 max). The researchers pooled data from two large cohorts, including a total of 1,128,290 participants, and divided them into three groups based on levels of fitness. Compared to the most fit individuals, those with low levels of cardiorespiratory fitness had 76% greater risk of developing depression, and those with medium levels of fitness had 23% higher risk of depression. This study reinforces the underappreciated link between physical and mental health.

Researchers had 10 healthy preschool-age children go through two different experimental conditions. One condition was a day of normal sleep (nap and regular bedtime), and the other condition was a day of sleep restriction (no nap and bedtime delayed by 2.3 hours). After the children's sleep was restricted (on average they lost about 3 hours of sleep), they consumed 21% more calories and 25% more sugar. Even a day later, when they were allowed to catch up on their sleep, their caloric intake was up 14% from baseline.

Researchers analyzed data from 91,105 participants, whose rest and activity patterns were recorded by using wrist-worn accelerometer for 7 days. From this data, they calculated the relative amplitude of their rest-activity cycles, meaning the extent to which the circadian rhythm of rest and activity is disrupted. The lower the relative amplitude, the more disrupted the circadian rhythm is thought to be. They found that a 1-quintile reduction in relative amplitude was associated with 6% increased odds of lifetime depression and 11% higher odds of lifetime bipolar disorder. Disrupted circadian rhythmicity was also associated with greater mood instability, higher neuroticism, more loneliness, and less happiness. These associations were independent of demographic, lifestyle, and education factors. Maintaining a regular sleep-wake cycle and managing factors that could disrupt biological rhythms (like light at night) may be key factors in sustaining good mental health.

Ginny says: I can’t believe I didn’t mention this sooner. I bought this on a whim at Kroger a while back and was absolutely blown away by it. I’ve used matcha for a long time, but I have never seen such a brilliant green hue as with this product, and the flavor is clean and sweet. Matcha, in case you don’t know, is a powder made from finely ground green tea leaves. Because you are ingesting the whole plant, as opposed to an infusion like when you use tea bags, you are getting waaaaaay more of the bioactive catechins, like EGCG (be aware that this also means a bit more caffeine). I personally prefer the flavor of matcha too, and it’s easy to add it to smoothies, drinks, etc. This particular brand is pretty pricey, but a little should go a long way since there are no fillers, sweeteners, dairy solids, or other additives that you commonly see in matcha products if you check the ingredient labels.

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