Not so Sweet

Hello and welcome to the Nutrition Facts podcast. I’m your host, Dr. Michael Greger. 

Now, I know I’m known for explaining how not to do certain things  (just look at my books, How Not to Die, the one I’m working on right now–How Not to Diet), but what I actually have to share with you is quite positive and boils down to this: What’s the best way to live a healthy life?  Here, are some answers.

Today we take a close look at sweeteners.  Artificial sweeteners may be found in everything from breath mints and chewing gums to jams, jellies, and juices, and even energy bars and yogurts. Is one healthier than another?  Sugar is no longer considered just empty calories, but potentially an independent risk factor for cardiovascular disease. So, what happens if you switch to artificial sweeteners? Here are some answers. 

Recommendations to limit sugar consumption vary around the globe, with guidelines ranging from “Limit sweet desserts to one every other day” to “Keep sugar consumption to 4 or less occasions per day.” In the U.S., the American Heart Association is leading the charge, “proposing dramatic reductions in the consumption of soft drinks and other sweetened products.” They recommend sticking to under about 5% of calories a day from added sugars, which may not even allow a single can of soda.  Why the American Heart Association? Because the “[o]verconsumption of added sugars has long been associated with an increased risk of cardiovascular disease”— meaning heart disease and strokes. We used to think that added sugars was just “a marker for [an] unhealthy diet.” At fast food restaurants, people are probably more likely to order a cheeseburger with their super-sized soda than a salad.

But the new thinking is that no, the added sugars in processed foods and drinks may be “an independent risk factor” in and of itself—worse than just empty calories, but actively disease-promoting calories.  We went from eating 7 pounds of sugar every year 200 years ago, to 50 pounds, to now over 100 pounds of sugar. We’re hardwired to like sweet foods, because we evolved surrounded by fruit—not Fruit Loops. But, this adaptation is “terribly misused and abused” today, hijacked by the food industry for our pleasure, and their profits.

“Why Are We Consuming So Much Sugar Despite Knowing [How] Much [it] Can Harm Us?” Well, yes, it may have an addictive quality. Yes, there’s that hard-wiring. But, the processed food industry isn’t helping.

Seventy-five percent of packaged food products in the United States contain added sweeteners, mostly coming from sugar-sweetened beverages, like soda, thought responsible for more than a hundred thousand deaths worldwide, and millions of years of healthy life lost.

No problem, why not just switch to diet? By choosing diet soda, can’t we get the sweet taste we crave, without the downsides? Unfortunately, “[r]outine consumption of diet soft drinks is [associated with] increases in the same risks that many seek to avoid by using artificial sweeteners.”

“In other words, the belief that [switching to diet soda will] reduce long-term health risks is not [well] supported by scientific evidence, and instead…may contribute to the very health risks people [were] seeking to avoid” in the first place.

But why? I mean, it makes sense why drinking all that sugar might increase stroke risk, with the extra inflammation and triglycerides. But why, in this pair of Harvard studies, did a can of diet soda appear to increase stroke risk the same amount? Yes, maybe the caramel coloring in brown sodas, like colas, may play a role. But, another possibility is that “artificial sweeteners may increase the desire for sugar-sweetened, energy-dense beverages/[and] foods.”

See, the problem with artificial sweeteners “is that [there’s] a disconnect [that] ultimately develops between the amount of sweetness the brain tastes and how much [blood sugar] ends up coming [up] to the brain.” The brain feels cheated, and “figures you have to eat more and more and more sweetness in order to get any calories out of it. As a consequence, at the end of the day, your brain says, ‘OK, at some point I need some [blood sugar] here.’ And then, you eat an entire cake, because [nobody] can hold out in the end.”

If you give people Sprite, Sprite Zero, or unsweetened carbonated lemon-lime water, and you don’t tell them what is what, and what the study’s about, and then, later on, you offer them a choice; they can have M&Ms, spring water, or sugar-free gum. Guess who picks the M&Ms? Those that drank the artificially-sweetened soda were nearly three times more likely to take the candy than either those that consumed the sugar-sweetened drinks or the unsweetened drinks. So, it wasn’t a matter of sweet versus non-sweet; it wasn’t a matter of calories versus no calories. There’s something about noncaloric sweeteners that tricks the brain.

Then, they did another study in which everyone was given Oreos, and they asked people how satisfied the cookies made them feel. And again, those that drank the Sprite Zero (the artificially-sweetened Sprite) reported feeling less satisfied than either the normal Sprite or the sparkling water. “These results are consistent with recent [brain imaging] studies demonstrating that regular consumption of [artificial sweeteners] can alter the neural pathways responsible for the [pleasure] response to food. The only way [to] really prevent this problem – to break the addiction – is to go completely cold turkey and go off all sweeteners” – artificial, as well as [table sugar, and high fructose corn syrup]. Eventually, the brain resets itself, and you don’t crave it as much.”

We’ve always assumed that “[c]onsumption of both sugar and artificial sweeteners may be changing our palates or taste preferences over time, increasing our desire for sweet foods. Unfortunately, the data on this [were] lacking”—until now.

Twenty folks “agreed to cut out all added sugars and artificial sweeteners for 2 weeks,” and afterwards, “95%…found that sweet foods and drinks tasted sweeter or too sweet, and…said moving forward they would use less or even no sugar” at all. And most “stopped craving sugar” within the first week, “6 days.”

This suggests a two-week sugar challenge, or even one-week challenge may “help to reset taste preferences, and make consuming less or no sugar easier.” And so, maybe we should be recommending it to our patients. 

“Eating fewer processed foods and choosing more real, whole, [and] plant-based foods make it easy to consume less sugar.”

The reason artificially sweetened beverages have been associated with depression may be because of psychological disturbances attributed to aspartame, sold as Equal or NutraSweet.

In a Harvard study of hundreds of thousands of people compared to non-coffee drinkers, those drinking up to four or more cups a day only appeared to have half the suicide risk. What about more than four? A Kaiser Permanente study of a hundred thousand people found that suicide risk continued to drop, 80% lower at more than 6 cups a day. Eight or more cups a day, though, is associated with increased risk. Perhaps those with more severe forms of depression try to use very high doses of coffee as a form of self-medication to make themselves feel better but was nonetheless, insufficient to elevate their mood.

It may also matter what goes into the coffee. The NIH-AARP study of hundreds of thousands of Americans followed for years, found that frequent consumption of sweetened beverages, especially diet drinks, may increase depression risk among older adults, whereas coffee consumption may lower the risk. Whether soda, or fruit-flavored drinks, or iced tea, those artificially sweetened appeared to carry higher risk. Same with hot tea or coffee. There was a benefit in coffee drinkers compared to non-drinkers, but add sugar and much of that benefit disappears, and add Equal or Sweet’n Low, and the risk may go up.

Various effects of artificial sweeteners, including neurological effects, have been suspected. For example, aspartame—the chemical in Equal and NutraSweet—may modulate brain neurotransmitters such as dopamine and serotonin, although data have been controversial, inconsistent. Scientific opinions range anywhere from “safe under all conditions” to “unsafe at any dose.”

The controversy started in the ‘80s soon after aspartame was approved. Researchers at the Massachusetts College of Pharmacy and MIT noted that given the very large number of Americans routinely exposed, if only 1% of the 100,000,000 Americans thought to consume aspartame ever exceed the sweetener’s accepted daily intake, and if only 1% of this group happen coincidentally to have an underlying disease that makes their brains vulnerable to the effects, then the number of people who might manifest adverse brain reactions attributable to aspartame could still be about 10,000, a number on the same order as the number of brain and nerve-related consumer complaints already registered with the FDA before they stopped accepting further reports of adverse reactions to the sweetener.

Who might be especially vulnerable? Those with a history of depression. Researchers at Case Western designed a study to ascertain whether individuals with mood disorders are particularly vulnerable to adverse effects of aspartame. Although they had planned on recruiting 40 patients with depression and 40 controls, the project was halted early by the Institutional Review Board for safety reasons because of the severity of reactions to aspartame within the group with a history of depression. It was decided that it was unethical to continue to expose people to the stuff.

It’s interesting, normally when you study something, a drug or a food, the company usually donates it to the researchers because they’re proud of the benefits or safety of their product. But the NutraSweet Company refused to even sell it to them, but they managed to get their hands on some, and within a week there were significantly more adverse effects reported in the aspartame group than in the placebo group. They concluded that individuals with mood disorders may be particularly sensitive to aspartame, and therefore its use in this population should be discouraged.

In a review of the direct and indirect cellular effects of aspartame on the brain, it was noted that there are reports of aspartame causing “neurological and behavioral disturbances in sensitive individuals:” headaches, insomnia, seizures, but they go further and propose that “excessive aspartame ingestion might be involved in the [development] of certain mental disorders and also in compromised learning and emotional functioning.” They conclude that due to all the adverse effects caused by aspartame, it is suggested that “serious further testing and research be undertaken to eliminate any and all controversies,” to which someone wrote into the journal that there really is no controversy; aspartame really is potentially toxic stuff.

But what do they mean excessive ingestion? The latest study on the neurobehavioral effects of aspartame consumption put people on a high aspartame diet compared to a low aspartame diet. But even the high dose at 25 mg/kg was only half the kind of limit set by the FDA, so the FDA says one can safely consume 50 a day, but after just eight days on half that, participants had more irritable mood, exhibited more depression, and performed worse on certain brain function tests. And these weren’t people with a pre-existing history of mental illness—these were just regular people. They conclude that given that the higher intake level tested was well below the maximum acceptable daily intake level—40 mg/kg in Europe, 50 mg/kg here—careful consideration is warranted when consuming food products that may affect neurobehavioral health. Easier said than done, since it’s found in over 6,000 foods, apparently making artificial sweeteners impossible to completely eradicate from daily exposure. Impossible? While that may be true for the great majority of Americans, it’s only because they elect to eat processed foods.  So, that’s another reason to stick to whole foods. Then, you don’t even have to read the ingredients lists, because the healthiest foods in the supermarket are label-free; they don’t even have ingredient lists.

To see any graphs, charts, graphics, images or studies mentioned here, please go to the Nutrition Facts podcast landing page.  There, you’ll find all the detailed information you need – plus links to all the sources we cite for each of these topics.

Be sure to check out my new How Not to Die Cookbook.  It’s beautifully designed, with more than 120 recipes for delicious, plant-based meals, snacks and beverages.  All the proceeds from the sales of all my books all go to charity.  I just want you to be healthier.  

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Thanks for listening to Nutrition Facts. I’m Dr. Michael Greger.

This is just an approximation of the audio content, contributed by Allyson Burnett.