The lactic acid that makes yogurt tangy is the same lactic acid that builds up in our muscles when we exercise strenuously. Instead of bacteria fermenting the sugar in milk to make energy for themselves, our muscles ferment sugar in our diet to produce energy to contract. If, like when we’re sprinting, lactic acid builds up in our muscles faster than it can be removed we can end up with a burning sensation in our muscles, forcing us to stop.
Now if we train we can increase the number of blood vessels in our muscles and clear out the lactate faster. For example, if you take some “overweight sedentary women” and start them on an aerobic training program of running and walking, at the end of three months their lactate levels during exercise dropped 17%. But those on the same program who drank 2 cups of orange juice a day dropped their levels 27%. They did the same exercise program, but the citrus group experienced a significant decrease in blood lactate concentration, indicating an improvement in physical performance with less muscle fatigue.
I don’t recommend drinking juice, though, because you’re losing all that wonderful fiber that slows the rate of fruit sugar absorption into our system. If you click on the above video, you can see the blood sugar spike one might expect after drinking Coca-Cola. Compare that to the spike you see with orange juice? No difference. However, if you eat the same quantity of sugar in the form of orange slices you experience a significantly smaller spike in blood sugar.
So the whole fruit is nearly always better than fruit juice. Now this is not to say OJ isn’t better than coke. OJ has those citrus phytonutrients like hesperidin, which may be why the women’s triglycerides didn’t go up even though they were drinking 2 cups of fruit juice every day. Hesperidin may actually help lower our digestion of fats, but once you get up to 3 cups a day you really can start bumping your triglycerides.
The burning sensation during strenuous exercise may be related to the build-up of lactic acid in our muscles, but that’s different than the delayed onset muscle soreness that occurs in the days following a bout of extreme physical activity. That’s thought to be due to inflammation caused by muscle cell damage, little micro-tears in the muscle. If it’s an inflammatory reaction then might anti-inflammatory phytonutrients help? Find out in my video Reducing Muscle Soreness with Berries.
More about what citrus phytonutrients can do in my previous video, Keeping Your Hands Warm with Citrus.
Michael Greger, M.D.