Tart Cherries & Metabolic Syndrome

A recent study found that a specific type of tart cherries can improve health conditions for adults with metabolic syndrome, which I blogged about not too long ago. For this blog post, we’re traveling to an area of France just north of Paris…

Montmorency tart cherries look just like the little cherries you’ll find while playing Pac-Man. These cherries are bright red and not sweet – not your normal grocery store cherries. But they’re packed with beneficial compounds unique to plants called phytonutrients. In this case, we’re focusing on a specific type of phytonutrient: anthocyanins.

Know Your Cherries

Cherry Type Taste Color Health Benefits
Rainier Cherry Sweet Yellow No Anthocyanins
Bing Cherry Sweet (slightly more so than Rainier) Dark Red Anthocyanin-rich + anti-inflammatory properties
Montmorency Cherry Sour/tart Bright Red Anthocyanin-rich + cherry type most often studied for potential health benefits

Know Your Anthocyanins

Anthocyanins are in the flavonoid family of polyphenolic phytonutrients. Like all phytonutrients, they are non-nutritive bioactive compounds, non-nutritive meaning they are healthy in a different way than macronutrients (protein, fat, carbohydrate) and micronutrients (vitamins and minerals). Like some other phytonutrients, anthocyanins provide both health benefits and pigmentation (reds, purples, and blues).

About Montmorency Tart Cherries A.K.A. Prunus cerasus

Montmorency tart cherries get their name from the first place that ever cultivated them in the 18th century, a commune in the northern suburbs of Paris, France. Now, Montmorency tart cherries are the most common variety of tart cherries grown in the United States; three-fourths of all Montmorency tart cherries grown in the U.S. are grown in Michigan.. They are available year-round in various forms: dried, frozen, canned, juice, and juice concentrate.

Both the bright-red color and sour-tart taste of these cherries come from their rich supply of polyphenols. In addition to anthocyanins, Montmorency tart cherries also have kaempferol and quercetin (also flavonoids) and chlorogenic acids (a type of phenolic acid and the main polyphenol found in coffee).

Additionally, Montmorency tart cherries are a rich source of melatonin, which is associated with sleep. These tart cherries actually contain six times more melatonin than Balaton tart cherries. Interesting fact – if you’re consuming tart cherries for sleep reasons, you might be better off eating straight cherries instead of juice because melatonin is unstable and may degrade during juice processing.

Montmorency Tart Cherries: A Small Pilot Study

A research group from the University of Hertfordshire (Hatfield, UK) published the results of a small study recently in the Journal of Functional Foods. Why study tart cherries? Lead author Terun Desai attributes the healthy qualities of Montmorency tart cherries to the “synergistic influence of anthocyanins, other polyphenols, and fiber.”

Desai’s small pilot study was the first to study Montmorency tart cherries in the specific context of metabolic syndrome, which affects 35% of U.S. adults.

Researchers conducted a randomized, placebo-controlled crossover trial. The study lasted six weeks with a 14-day washout period and included 11 male and female participants between the ages of 37 and 61. Participants had to meet at least three of these metabolic syndrome criteria defined by the study:

    • Waist circumference >35” (female) or >40” (male)
    • High or borderline high triglyceride levels
    • Low HDL
    • High blood pressure
    • High fasting blood sugar

Note: These five metabolic syndrome parameters are slightly different than the four parameters I list in my blog. I list “dyslipidemia” which includes both low HDL, high LDL, and high triglyceride levels. Additionally, “insulin resistance” goes hand in hand with “high fasting blood sugar.”  This is because when cells are resistant to insulin, glucose levels in the blood increase even when you haven’t had a meal in a while (“fasting”).

Participants consumed each of these three things on three different occasions, each separated by two weeks:

    • Montmorency tart cherry juice
    • Montmorency tart cherry capsules
    • Placebo drink

The cherry juice and cherry capsules contained the same amount of anthocyanins, and they matched about the same number of whole tart cherries. The placebo drink tasted just like the cherry drink, with the study scientists controlling for taste, calorie count, and visual appearance.

Scientists regularly monitored parameters like:

  • Heigh, weight, and waist circumference
  • Arterial stiffness, blood pressure, and heart rate
  • Cardiac output, stroke volume, and mean arterial pressure
  • Total peripheral resistance and resting metabolic rate
  • Glucose and insulin levels, insulin resistance or sensitivity, and blood lipids

Don’t know what all of those words mean? No worries. Basically, all of these measurements were taken because the values are associated with heart and metabolic health. The study scientists wanted to see how each of the three consumable components affected or did not affect these measurements.

Ultimately, their research led to the conclusion that Montmorency tart cherry juice produces a “significant, clinically-relevant” reduction in systolic blood pressure compared to the placebo drink. As a reminder, “systolic” blood pressure refers to the first or top number in a blood pressure reading, i.e. the “120” in “120/80.” This reduction was seen just two hours after consumption. Both the cherry juice (at one hour) and the cherry capsules (at three hours) showed an insulin-lowering effect.

The study scientists acknowledge (rightfully so) that their results are preliminary and more research should be done before making more concrete claims. There were only 11 people in this study, and the more people in the study, the more reliable the results!

Interestingly, the scientists originally thought that the Montmorency tart cherry capsules would produce greater effects on metabolic syndrome parameters than the cherry drink. The logic behind this is that the anthocyanins in the capsules would be more biologically available, but there really wasn’t a huge difference in effect between cherry juice and cherry capsules.

Read the press release

Read the study

Other sources

ChowHound

Journal of Agricultural and Food Chemistry

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