DEAR DR. BLONZ: Is it dangerous to eat an entire apple, including the seeds? One of my friends does this all the time, but I know there is cyanide in apple seeds. I have mentioned it and he said he has been doing it his entire life. -- H.N., Piedmont, Calif.
DEAR H.N.: You are correct about the cyanide. Apple seeds -- along with apricot kernels, peach pits, cherry pits and stems, and the leaves and roots of some rose family species -- are natural sources of the cyanide-containing compound known as amygdalin. Cyanide has an ability to quickly and effectively slow down body metabolism, so it can be a very potent poison. But as with most toxic materials, it is the dose that's the key.
The body has a recovery mechanism that can cope with small amounts of cyanide, and the relative amount of amygdalin in the seeds of one apple does not represent a significant health risk. There is little to worry about if you happen to eat the seeds while enjoying your apple.
Consider also that apple seeds have a rather tough seed coat that is difficult to digest. Most seeds pass through the digestive tract intact -- that is, without transferring any amygdalin to the person eating them. (Actually, this is a method of seed dispersal found in nature: An animal in one location eats the entire fruit and eventually expels the seeds in a new location.) Because whole-fruit blenders and juicers crush the seeds, and because multiple apples can be used in one serving, it would be prudent for those using these devices to remove the seeds beforehand.
DEAR DR. BLONZ: Does it become dangerous to drink orange juice once it has become slightly fizzy? How does this differ from carbonation? -- R.L., Berkeley, Calif.
DEAR R.L.: Fizz, when intentional, comes from carbonation, which is the addition of carbon dioxide gas (CO2). Carbon dioxide will not dissolve well into warm water, but it becomes more soluble as the temperature goes down. Pressure helps "hold" the gas in solution. This explains the "pop" and greater release of gas when a soda is uncapped at room temperature. At best, the carbon dioxide is only loosely held in the water, which explains why agitations such as pouring a warm soda over ice, or shaking the bottle, brings forth a gaseous eruption.
When you consume carbonated beverages, some of the swallowed gas can be absorbed and exits the body through exhaled air. The rest exits the body through belching, a process by which the esophagus opens and allows the pent up gas out from the stomach. If it manages to make its way past the stomach, the gas can pass through the GI tract and exit at the other end.
Fizz that develops in orange juice is a sign of spoilage due to microbial fermentation of the sugars in the juice. The fermenting organism gives off carbon dioxide gas that can be detected by your tongue, thus giving a sensation similar to that caused by carbonation. There will also tend to be a loss of sweetness during this type of spoilage since the fermentation organisms feed off the simple sugars for fuel. Because the spoilage organism is unknown and there is a potential health risk, it is best to discard the juice when you sense any type of unplanned fizz.
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