01/23/2015 11:05 am ET Updated Mar 25, 2015

Soda Or Diet Soda? A False Choice

Shutterstock / Tiago M Nunes

What's better to drink, regular soda or diet soda? This is probably one of the most common questions fielded by nutrition and health experts. I think that the answer is clear -- diet soda -- but the choice is a false one.

Coke, Pepsi, Mountain Dew, and other sugar-based sodas are just about the worst items in the American diet. Each 12-ounce can contains roughly 10 teaspoons of sugars. Unlike almost all other caloric foods, sodas provide nothing of nutritional value. Drink too much, and they could lead to diabetes, obesity, and tooth decay and even contribute to heart disease. Diabetes has terrible consequences, including blindness, erectile dysfunction, amputation, and shortened life span.

Ask any weight loss surgeon or dietitian: If you want to lose weight and reduce your risk of those conditions, stop drinking your calories! Soda, energy drinks, fruit drinks, sports drinks, and other sugary beverages are all part of the problem. It's almost as if these flawed and unsafe products were specifically engineered to cause health problems.

If for some reason you must drink a soda, diet soda is a better choice. But most of the artificial sweeteners used in those drinks are poorly tested. And when they have been tested in laboratory animals, some of the results have been worrisome.

Take aspartame, the most widely used artificial sweetener in beverages. You can find it in Diet Coke (by far the best-selling diet soda), Diet Pepsi, Coke Zero, Diet Dr Pepper, Diet Mountain Dew, Red Bull Sugar Free, Great Value Diet Cola, Sam's Choice Diet Cola, and many others. A chemical combination of two amino acids and methanol, aspartame has caused multiple kinds of cancer in two tests conducted by a respected independent research institute on male and female rats and another study on male mice. Scientists generally agree that if a substance causes cancer in lab animals, it likely is linked to cancer in humans. (It's almost impossible to identify carcinogens in human studies, except for the most potent substances, such as tobacco smoke, or when workers are exposed to huge doses, as was the case for asbestos.)

Safety tests of acesulfame-potassium, or ace-K, also do not inspire confidence. Ace-K is used in Coke Zero, Diet Pepsi, Diet Mountain Dew, Great Value Diet Cola, Sugar-free Red Bull, and other drinks. It is little known, perhaps because of its strange chemical name, but it is found in far more products than even aspartame. Two rat studies commissioned by aspartame's manufacturer (Hoechst) in the 1970s suggested that ace-K might cause cancer. No independent studies have examined this artificial sweetener.

The newer sucralose (sometimes marketed as Splenda) has been grabbing market share from aspartame and is the most widely used artificial sweetener in foods. I've long thought that it is safe, but a 2011 report, not yet published, found that sucralose caused leukemia in mice. We will need to review the status of sucralose if and when that study is published.

There are other questions on the margins surrounding artificial sweeteners, such as whether they condition one's palette to demand sweet foods, whether they interfere with the bacteria in one's gut, and so on. And there also are other questions about diet drinks, because they, like their sugary cousins, are often made with teeth-eroding phosphoric acid, mildly addictive caffeine, caramel coloring that may be contaminated with the carcinogen 4-methylimidazole, and dyes that can trigger hyperactivity in kids.

So the choice between soda and diet soda is basically down to this: The clear-cut risks of obesity and other health problems that affect high percentages of dedicated soda drinkers on the one hand, versus the less-common potential risk of developing cancer. Interestingly, Americans seem to be shunning both types of beverage: Per-capita consumption of diet carbonated drinks has declined by 13 percent and of regular carbonated drinks by 25 percent since 1998.

The Food and Drug Administration could help matters by improving both categories of beverage. It could require, as the Center for Science in the Public Interest petitioned for in 2013, manufacturers to sharply reduce -- perhaps by 75 percent -- the amount of sugars used in regular sodas. Doing that would largely eliminate soda pop as an obesity threat.

And the FDA could ban aspartame and Ace-K until independent animal studies demonstrated their safety. Already, companies are beginning to use natural, high-potency sweeteners derived from stevia, monkfruit, and other plants that are probably safe. For example, one brand of no-calorie soda, Zevia, is sweetened with stevia, monkfruit, and the safe sugar alcohol erythritol. FDA should be nudging soda makers in that general direction.

But why pretend that soda and diet soda are the only choices? Tap water, bottled water (when out and about), and flavored waters are safe choices. Seltzer water, perhaps spiked with a little fruit juice, is another refreshing choice. Unsweetened iced tea is fine. If you want to get fancy, water infused with berries, slices of cucumber, or citrus fruits, and herbs like basil or mint is a great choice for entertaining a crowd. You won't see many advertisements or celebrity endorsements for those healthiest choices (we're looking at you Beyoncé and Taylor), but they beat both soda and diet soda hands down.