We continually hear about the benefits of fruits and vegetables for better health. There are a number of them. One is obviously their lower glycemic load that reduces insulin secretion. Another is their polyphenol content that gives fruits and vegetables their colors. Although virtually no research was conducted on polyphenols before 1995, since that time there has been a explosion of animal studies that have indicated their remarkable benefits as anti-oxidants and anti-inflammatory agents.
Upon deeper inspection, there is one group of polyphenols that seems to generate the most consistent health benefits. These are the delphinidins. Delphinidins are a subgroup of a family of polyphenols known as anthocyanidins. To make the story about delphinidins more intriguing, they are primarily found in blueberries. More specifically, the primary sources of delphinidins are the American blueberry, the Russian blueberry (i.e. bilberry), and the Patagonian blueberry (i.e. maqui berry). This is why the published clinical studies in humans seem to consistently involve blueberries. And the clinical data is impressive. Whether it is about reducing oxidized cholesterol or improving insulin resistance in patients with metabolic syndrome (1,2) or improving memory in patients with early dementia (3), the human data on the use of blueberries simply jumps out at you.
Since the active ingredient in each of these varieties of blueberries appears to be the delphinidins, then it is reasonable that the higher the levels of this particular polyphenol, the better the potential results. The Russian blueberry contains six times more delphinidins than American blueberries, and the Patagonia blueberry contains 14 times more delphinidins than the American blueberry. This probably reflects the harsher growing climates that other forms of blueberries are exposed to when compared to the American blueberry, which has become overly domesticated (making it richer in fructose and lower in delphinidins).
However, as with all natural products you have to take a therapeutic dose to get a therapeutic effect. You could measure this therapeutic threshold in terms of their anti-oxidative potential (measured in ORAC units) or the actual amounts of delphinidins themselves. It appears that for a blueberry extract to be effective requires that it provides at least 16,000 ORAC units per day. To put this in perspective, this level of ORAC units is equivalent to eating greater than 20-30 servings of vegetables on a daily basis.
But if the delphinidins are so important for the benefits of blueberries, isn’t it possible that the smaller amounts of the maqui berry might be even more beneficial because of its higher delphinidin concentration? That’s why we have several ongoing clinical trials to explore that potential. I will keep you informed as the results start coming in. Yet in the meantime, keep eating lots of those colorful carbohydrates just like your grandmother told you to eat.
- 1. Stull AJ, Cash KC, Johnson WD, Champagne CM, and Cefalu WT. “Bioactives in blueberries improve insulin sensitivity in obese, insulin-resistant men and women.” J Nutr 140: 1764-1768 (2010).
- Basu A, Du M, Leyva MJ, Sanchez K, Betts NM, Wu M, Aston CE, and Lyons TJ. “Blueberries decrease cardiovascular risk factors in obese men and women with metabolic syndrome.” J Nutr 140: 1582 1588 (2010).
- Krikorian R, Shidler MD, Nash TA, Kalt W, Vinqivst-Tymchuk R, Shukitt-Hale R, and Joseph JA. “Blueberry supplementation improves memory in older adults.” J Agric Food Chem 58: 3996-4000 (2010).
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