There are many misconceptions about what is healthy and what is not.  Fruit has been labeled healthy and so has become a large part of many childhood diets.  Surely things made from fruit have to be healthy, but is this the case? Many parents confidently give their kids juice boxes, specifically apple juice, but there are others; unaware of the real danger: concentrated sugar. As a practicing dentist, I can speak with some knowledge of sugar and the real danger it causes: Increasing the risk for tooth decay, diabetes, and obesity.

Dentistry, as a profession, does not have the resources to compete with major corporate food producers dollar for dollar in the advertising arena. We have done a reasonable job of getting the message out that sugar causes tooth decay. We have not done as well defining to the public what sugar is and where it is hidden in the products you buy. It is not just an amorphus white powder that comes in five pound bags, it is everywhere.  Neither is it mentioned that natural sugar has the same effect on your body that processed sugar.  Nor is it mentioned that sugars and all carbohydrates are not obligate nutrients. This means that if you do not consume them you will survive just fine.

The sugars in an apple are a mixture of fructose, glucose, and sucrose, as well as some small amounts of other sugar compounds. If you squeeze an apple or any fruit, all you do is remove the fiber and are left with the sugars mixed with water. The marketers may add vitamins or minerals so that they can write such things on the label as “Meets 100% of your daily vitamin C requirement.” (Vitamin C is not lacking in the standard American diet.) There is a list with sugar content of some popular juices here.

The sugar with the greatest concentration in apple juice is fructose. This is a special sugar because your body handles it differently than other sugars. Only your liver contains the proper enzyme in sufficient concentrations to metabolize fructose. The metabolic pathway it follows does not always lead to glucose. The liver is quite capable and efficient at turning fructose in glycine.   This forms the backbone in triglycerides. This is how consumption of juices with sugar can lead to a mouth full of cavities, obesity, diabetes, and high triglycerides. Not a good idea at all.

There are two types of tooth decay. The first type is called pit and fissure decay. This occurs in the grooves of the biting surfaces of your teeth when bacteria metabolize these sugars. The second kind, called smooth surface decay, occurs just like its name implies, on the smooth surfaces of your teeth. The bacteria that initiate this kind of decay utilize sucrose. They do not care if the sucrose comes from sugar cane or apple juice.   Marketers have convinced consumers that juice must be good for us, when the truth is apple juice causes tooth decay. A better choice is to have an apple and a glass of water instead. The fiber will help “dilute” the effects of the sugars, slow their absorption and provide a feeling of fullness or satiation.

Decay in a toddler

In addition to tooth decay, I mentioned that drinking apple juice raises the risk for diabetes and obesity. We know that in order to metabolize the sugar, the body produces the hormone insulin which signals the muscle cells to begin transporting it into the cells and burn it for fuel. It also signals the liver cells, but they do something quite different. . They begin to accumulate the sugars and turn them into fat. The fat then gets shipped to the fat cells for storage. Sugar also blocks another hormone, produced by the fat cells called leptin. This hormone signals your brain that you are full. Since this hormonal signal is now blocked, your hunger continues so you have another “healthy” juice box and the process continues. Breaking consumers of fifty years of marketing is a tall order but its past time someone starts.

I recommend a low carbohydrate approach. Since sugars are carbohydrates, be mindful that the fruit we currently eat has been bred for size and sweetness and is substantially higher in sugars compared to what our pre-agricultural ancestors ate. For example, I have wild blackberries growing in my backyard, they are ripe for about 1 week in early July and then they are gone. Each berry will fit neatly on my small fingernail. Store bought berries are about the size of my thumb.

A low carbohydrate approach allows for some fruit but is not a high fruit approach. Yes it is 100% natural, but so is arsenic. Know that fruit has sugar and will still cause your body to maintain high levels of insulin and start this destructive cascade. It is time and dose dependent. Juice has no fiber and will raise insulin quicker, leading to hunger and a desire for more.   This is great if you happen to sell apple juice but horrible for your well-being.

We do best with what we have the longest evolutionary history. Apple juice is brand new in our diets by comparison.

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