Newsletter #173: Dietary Flavonoids and Your Health 🍓
Good morning, humanOS friends! This week, we looked at some recent research examining the long-term effects of flavonoids in the diet, a topic that we have discussed on the blog previously a few times.
Flavonoids are a class of phytochemicals that are widely distributed in fruits and vegetables. In plants, they carry out a wide range of important functions, like coloration and protection against ultraviolet light. But they also appear to affect our bodies in various ways when we eat them.
For instance, flavonoids appear to boost bioavailability of nitric oxide, a molecule that relaxes the walls of blood vessels, which in turn reduces blood pressure and improves blood flow. Flavonoids are also metabolized by our gut bugs, where they may inhibit inflammation in the gut and even modulate the immune system. So it shouldn’t be too surprising that observational studies seem to show that eating more flavonoids is linked to better health.
To learn more, scroll on down 👇🏼
This Week’s Research Highlights
🫐 Higher intake of flavonoids is associated with lower blood pressure and arterial stiffness.
Researchers in Australia analyzed data on intake of a wide range of flavonoids and hemodynamics and arterial stiffness in 381 older adults. They found that each standard deviation per day higher intake of anthocyanins specifically was associated with significantly lower diastolic blood pressure and mean arterial pressure, and each standard deviation per day higher intake of flavanones was associated with 1% lower augmentation index (a measure of arterial stiffness that tends to increases with age). Notably, these associations were still significant after adjusting for dietary quality and for other nutrients that are known to affect blood pressure and arterial stiffness, like potassium, magnesium, fiber, etc. Anthocyanins, by the way, are blue, red, or purple pigments found in lots of edible plants and beverages (like wine and tea); flavanones are most abundantly found in citrus fruits. If you’d like to know more, we actually interviewed one of the authors of this study on our podcast a little while back.
🦠 A flavonoid-rich diet is linked to improved blood pressure, and this is partly explained by features of the gut microbiota.
To better understand the observed association between flavonoids and blood pressure, researchers examined food intake and blood pressure levels in a group of 904 adults in Germany, as well as gut microbiome samples. As you might expect, study participants who had the highest intake of total flavonoids had lower blood pressure and a more diverse gut microbiome, compared to those with the lowest intake. In food-based analyses, they determined that consuming ~128 grams of berries per day was linked to an average reduction in blood pressure of 4.1 mmHg, and drinking 350 mL of wine (or almost three glasses) was associated with an average of 3.7 mmHg lower systolic blood pressure. Modeling suggesting that aspects of the gut microbiota explained up to 15.2% of the link between flavonoid-rich foods and blood pressure.
🧠 Dietary flavonoids are linked to better brain health later in life.
Researchers from Harvard followed 49,493 women from the Nurses’ Health Study and 27,842 men from the Health Professionals Follow-up Study. Over twenty years of follow-up, subjects repeatedly completed detailed questionnaires on how often they ate various foods, and answered questions assessing their cognitive abilities. After adjusting for age and total energy intake, the researchers found that people in the highest 20% of flavonoid consumption had about 20% less risk of cognitive decline, compared to those in the lowest quintile of intake. To put this into perspective, the people with the highest intake had about 600 mg of flavonoids daily, which is actually pretty easy to achieve (strawberries have around 180 mg of flavonoids per 100 grams). Effects also varied by individual flavonoids. For example, flavones (found in yellow/orange foods and some spices) were associated with a 38% reduction in risk of cognitive decline, and anthocyanins were associated with a 24% reduced risk of cognitive decline. Author Walter Willett noted, "And it's never too late to start, because we saw those protective relationships whether people were consuming the flavonoids in their diet 20 years ago, or if they started incorporating them more recently."
💉 Higher flavonoid intake is linked to lower risk of diabetes as well as lower body fatness.
Researchers in Australia examined data on body fat, flavonoid intake, and diabetes incidence in a large Danish cohort (n=54787) who were followed for 23 years. They found that subjects in the highest total flavonoid intake quintile had 1.52 kg less body fat and a 19% reduced risk of diabetes, compared to the lowest quintile of intake. Further analysis found that body fat mediated 57% of the association between diabetes and flavonoid intake. However, it is probably worth noting that body fat in these participants was estimated via bioelectrical impedance, which is a quick and easy method to measure body fat percentage but is quite limited.
Random Trivia Question of the Week
🤔 Most of us are familiar - perhaps all-too-familiar - with burpees. But do you know where the exercise originally came from?
(Also, if you want to feel really humbled, scroll down and take a look at the burpee world records 😳 )
💡 ANSWER
Podcasts We Loved This Week
- Christoffer Clemmensen: Therapeutic strategies to correct obesity and its disorders. Via STEM-Talk.
- Gretchen McCulloch: Your language is changing - Because Internet. Via Science Friday.
Products We Are Enjoying
Pizza Flavored Plant Based Dip + Spread
I stumbled upon this stuff randomly at Target a couple of weeks ago and I am very glad that I decided to give it a shot. It is a super tasty (and healthy) dip/spread made from cashews, with no artificial flavors, colors, or preservatives. Perfect to spread on top of bread or sweet potatoes or whatever you fancy.
humanOS Catalog Feature of the Week
Thank you, as always, for reading, and see y'all next week!