One of the more popular sweeteners is sucralose which is marketed as Splenda. The sucralose molecule has the same chemical structure as sucrose (regular sugar) except that it replaces three oxygen atoms in sucrose with three chlorine atoms which caused some alarm among chemists in the late 90s when Splenda was first developed. An article by chemist Josh Bloom at the website of the American Council on Science and Health explains why:
The most obvious red flag for toxicity is a molecule that appears to be chemically reactive. Reactive molecules often cause trouble because, as the name implies, they react with biomolecules in the body (proteins or DNA, for example) and can alter their structures. This alteration can change or even disable the function of proteins or DNA, and this is what is usually responsible for toxicity.Yikes! So why think it's safe? Bloom explains:
Because of this property, there are not many reactive drugs on the market. The main exceptions to this are certain cancer drugs, many of which (especially the older ones) are intentionally made to be reactive, since they work by poisoning cancer cells (and also non-cancerous cells).
Any trained organic chemist can identify hot spots [indicators] that make molecules reactive....This is why sucralose raised a few eyebrows when it was approved by the FDA in 1998. The sweetener doesn’t have one potential hot spot. It has three.
Sucralose is identical to sucrose (cane sugar), with one exception — the three chlorine atoms .... In sucrose, those chlorine atoms are oxygen. But, it is these chlorine atoms that turn sugar into something with no calories. This is because the two chemicals are handled very differently in your body.Evidently, the sucralose molecule is essentially inert, passing through and out of the body without having reacted with anything.
After you swallow sucrose, an intestinal enzyme called sucrase rapidly converts it to a 1:1 mixture of glucose and fructose. Both of these sugars have plenty of calories. But sucrase doesn’t recognize sucralose as sugar so the enzyme does not react with it or break it down. As a result, almost all sucralose passes through your digestive system without being absorbed. This is why it has zero calories.
Bloom includes a number of other interesting facts about sucralose in his article. Here are a couple:
The three chlorine atoms make sucralose 600 times sweeter than sucrose. A can of Pepsi One contains 60 mg of sucralose. A can of regular Pepsi contains 41 grams (41,000 mg) of sugar. So, even if sucralose was caloric, you’d only need 600-times less of it to get the same sweetness.If Bloom is right - and I'm not vouching for his accuracy because I'm not a chemist - it sounds like you can use as much Splenda as you want without having to worry that you're damaging your health.
It was impossible to kill rodents that were given insanely high doses of sucralose. Mice and rats that were fed single doses of 16 and 10 grams per kilogram of body weight, respectively, did not die. This is roughly equivalent to one kilogram (2.2 pounds, or 1,000,000 mg) in humans. You would need to drink 17,000 cans of Pepsi One to get that much.