Blueberries, and also cherries and grapes, contain phenols which are known to chemists as anthocyanins. According to nutritionists at the American department of agriculture, these compounds have a body recompositioning effect. They reduce the amount of fat and increase lean body mass.
The researchers did an experiment with mice that lasted 72 days. The animals were given a low-fat [LF] or a high-fat [HF] diet. Some of the animals were given a blueberry juice supplement [BBJ], others were given pure anthocyanins extracted from blueberries and dissolved in their drinking water [ACN]. The ACN group were given 0.2 mg anthocyanins per ml drinking water.
The researchers were looking for anti-obesity effects, and found these in both groups. The tables below show that anthocyanins supplementation in particular had a qualitative effect on the mice's weight gain. The blueberry extract helped the mice to gain more lean body mass and less fat.
The researchers were able to work out how the blueberry effect worked by examining the mice's blood. The anthocyanins in the berries improved the insulin functioning. At least, the mice needed less insulin and their fat cells produced less leptin. Fat cells produce leptin when they grow. Putting it all together, it seems that anthocyanins enhance the effect of insulin in the muscle cells rather than in the fat cells. [We wonder - should we classify anthocyanins as AMPK-boosters?]
The anthocyanins ensure that the muscles slurp up most of the glucose from the blood, preventing the fat cells from growing too. That's why the supplementation has most effect in the low-fat diet group. The effect is even clearer when the researchers put 1 mg anthocyanins instead of 0.2 mg in a millilitre of drinking water.
Yes, the results are correct. In the high-fat diet group the higher dose of anthocyanins has no effect on the fat layers, but in the low-fat diet group the fat layer halves.
The composition of the anthocyanins that the researchers used is shown below. Compound 5 is the shaded one. The cyanidin-3-glucoside [structural formula shown above] is the active ingredient in Indigo-3G, Biotest's body recompositioning supplement. [Google]
J Agric Food Chem. 2010 Apr 14;58(7):3970-6.