I don’t know about you, but I had never heard of a cashew apple until a week ago. I learned about it when reading a recent study in the Journal of the International Society of Sports Nutrition about cashew apple juice, which apparently helps to burn fat. I have to admit I thought cashew apple juice sounded hilarious. I won’t lie – I thought this was regular apple juice with cashews in it. How they juiced the cashew was a perplexing and amusing thought to me.
Come to find out, the cashew apple is a particular kind of fruit that grows with the cashew nut. It’s popular in other parts of the world, such as South America and India, but has an astringent flavor that requires preparation to remove, and so is less popular here in the United States. At least, being in New England, I can say we do not know about it here.
In the study, researchers supplemented both trained and untrained individuals to find out if cashew apple juice increased the utilization of either fat or carbohydrates as a fuel. Turns out, it does help you burn more fat, but not carbohydrates. In fact, during exercise, the amount of carbohydrates burned didn’t just go unchanged. Use of carbohydrates went down, while the contribution of energy from fat went up.
The fact that fewer carbohydrates were burned is interesting. Generally, substrate utilization, meaning where the energy for your activities comes from, is greatly affected by what type of macronutrients you are consuming. In other words, if you consume more carbs, you’ll burn more carbs. Eat more fat, and you’ll burn more of that. So you can’t help but wonder what in the heck is going on here. No change in carbohydrate utilization might make plenty of sense depending on the participants’ diet, but to have a greater fat utilization comes as a surprise.
The proposed cause of the greater fat burn is vitamin C. Cashew apples are known for being high in vitamin C, to the tune of about five times the quantity found in an orange. That’s nowhere near a supplement level dosage, but from diet alone that’s about as much as you’ll come across.
Vitamin C is a necessary cofactor in the formation of the amino acid L-carnitine. Your body can make carnitine on its own, so it isn’t considered an essential amino acid. But problematically, your body’s capacity to produce carnitine has limits. This is important because carnitine is a required part of the fat-burning process. If you are either trying to lose weight or are an avid exerciser you may already be beyond your body’s ability to produce carnitine, and so it may become practically essential.
Generalizations are rarely good, but one that I can stand behind is that paying attention to an adequate carnitine status is important for virtually everyone. One way we can do this is through consumption of a beverage like cashew apple juice that is high in vitamin C. However, it is likely that supplemental vitamin C or carnitine itself will probably do the trick as well.
References:
1. Piyapong Prasertsri, et. al., “Cashew apple juice supplementation enhanced fat utilization during high-intensity exercise in trained and untrained men,” Journal of the International Society of Sports Nutrition 2013, 10:13
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