NEWSLETTER #182: Maximizing the Health Benefits of Fruit 🫐
Good morning, humanOS friends, hope y’all are having a fun and safe Halloween weekend!
This week, we came across some recent research on how various ways of processing fruits can enhance the accessibility of bioactive compounds to the body. We thought these were worth highlighting, in part because we are kind of evangelists for the health-promoting effects of phytochemicals, but also because some of them are kind of surprising and counterintuitive.
One of the studies, for instance, found that frozen blueberries may actually be a better source of polyphenols than fresh fruit, (which is particularly encouraging as we enter a part of year when fresh blueberries are a little harder to come by). We also learned that fruit smoothies have a lower glycemic index compared to the same volume of fruit consumed whole - seemingly because blending the fruit can unlock nutrients that slow down the absorption of sugars. Overall good news for smoothie enthusiasts.
This Week’s Research Highlights
🫐 Frozen blueberries are just as healthy as fresh, and freezing may even boost bioavailability of their polyphenols.
Researchers at South Dakota State University froze fresh blueberries and drew samples from them on a monthly basis to measure concentrations of anthocyanins, the polyphenols that are responsible for the characteristic blue hue of the berries. They found that anthocyanins not only did not deteriorate, but the concentrations increased with freezing time - average concentration increased by more than 2.5 fold after 133 days in the freezer. Lead author Marin Plumb suggests that the ice crystals that form during the freezing process disrupt the structure of the fruit tissue, which increases the bioavailability of the polyphenolic compounds locked inside the plant cells. However, it is worth noting that a subsequent study found that freezing blueberries increased antioxidant capacity initially, but that the anthocyanins began to degrade and antioxidant activity appeared to decline by around the six month mark, so you probably don’t want to leave your berries in the freezer for too terribly long.
🐮 Casein, one of the proteins found in cow’s milk, may help boost bioaccessibility of beneficial compounds in blueberries.
Researchers fed rats purified anthocyanin extracts, adding casein to the solution for one group of rodents. Over the following 24 hours, concentrations of anthocyanins and polyphenolic metabolites were 1.5 to 10.1 times higher in the rats that had been given casein, compared to the controls. To understand why this was the case, the researchers analyzed the molecular structure of casein and determined that its amino acids enabled it to interact with anthocyanin molecules, improving their stability and enabling better transport into circulation. Whether this finding applies to whole dairy products is unclear, as prior studies have found that milk may actually interfere with blueberry phenolics, but maybe isolated casein protein would be a good addition? Clearly more research is needed.
🍇 Blending fruit results in a lower glycemic index, compared to consuming the same fruit whole.
Researchers had participants consume two different test meals, with a 2-day washout period between test days. One meal was whole fruit, and the other meal was the same volume of fruit blended with a Nutribullet. They tested blood glucose levels at 15 minute intervals for the two hours following the meal and used the results to calculate the glycemic index values for each meal. Blending was shown to significantly lower the glycemic index for both raspberry + mango (25.43 ± 18.20 vs. 44.85 ± 20.18) and passion fruit + mango (26.30 ± 25.72 vs. 42.56 ± 20.64), compared to eating the same fruit combinations whole (incidentally, all of these values are still in the low range, so don't get the idea that eating whole fruit is bad!). The researchers suggest that the process of blending the fruit may have ground up the seeds in the passionfruit and raspberries, which in turn unlocked fiber, polyphenols, fats, proteins, and other substances in the seeds that could slow down gastric emptying and the rate of glucose absorption.
Random Trivia Question of the Week
🤔 What is the leading cause of injuries associated with Halloween, according to the U.S. Consumer Product Safety Commission?
(By the way, you should totally follow the USCPSC on Twitter, it is...decidedly not what you would expect from a government agency account)
🎃 ANSWER
Podcasts We Loved This Week
- Alan Flanagan & Danny Lennon: Polyphenols – Impact on blood pressure, endothelial function and heart disease risk. Via Sigma Nutrition Radio.
- Robert Gatenby: Viewing cancer through an evolutionary lens and why this offers a radically different approach to treatment. Via Peter Attia.
Products We Are Enjoying
Vitamix.
If you like to make smoothies, a high-powered blender is basically a must. Once you try it, you’ll never go back to typical countertop blenders. Trust me. There are a number of good ones, but I haven’t used any that surpass this one. And it’s an incredibly versatile device - you can also use it to make hot soup, nut butters, flours, etc. It’s just awesome.
If the price puts you off, you might do what I did and snag a refurbished model, or wait for a flash sale (premium kitchen appliances are often significantly reduced for Prime Day and on Black Friday/Cyber Monday).
humanOS Catalog Feature of the Week
Thank you for reading, and I will see y'all next week!