By Keith Ayoob, EdD

As a clinician of some 30+ years, I doubt I’ve seen a nutrition issue more polarizing than that of low-and no- calorie sweeteners (LNCS). 

You may have read sensational headlines about these sweeteners.  You should also be hearing about their benefits, but alas, good news never sells. 

Example: a recent study in the journal Stroke looked at the “association” between LNCS-containing beverages and the risk of stroke, coronary heart disease and “all-cause mortality”, the latter meaning essentially death for any reason at all.

The study focused on the consumption of artificially-sweetened beverages (ASBs) in over 82,000 women who were part of the Women’s Health Initiative Observational Study (WHIOS).  The women were enrolled quite a while ago, between 1993 and 1998, then followed for 12 years.  They reported their ASB intake only ONCE – 3 years after their initial enrollment.

This study is “observational”, as no intervention was involved.  Studies like the WHIOS generate huge databases, are relatively easy to do and don’t tend to cost much, given the number of research publications they can produce. However, this kind of data also has serious limitations (think “fine print”) to it.  Read on.              

The authors acknowledged the following limitations of the study:

• Though the authors note that this type of study is incapable of showing a cause-and-effect relationship, still, they tend to draw very specific conclusions from very generalized data.  Observational studies are only able to generate a hypothesis, even if headlines suggest otherwise.
• Since the intake of ASBs was recorded only once and was self-reported, it cannot be validated.  It should also be noted that diet quality was also taken at the time of enrollment and was not assessed again during the 12-year follow-up period.
• The authors noted that women with a higher intake of ASBs “may have differed systematically” from women with little or no intake, “since they were more likely to be obese and have a higher energy intake.” The authors acknowledged that they may have been components of their diets that were not accounted for by the diet quality measure utilized in the study. 
• The ASB intake assessment did not consider the use of LNCS in coffee, tea, or foods.  Therefore, subjects who are simply not soda drinkers and may use LNCS in their hot beverages, or eat sugar-reduced foods such as “lite” yogurt were not captured in this study.

How likely is it that your current health status is a result of what you usually ate on a typical Wednesday, 12 years ago?  The authors felt that, in weight-stable older women, “the likelihood of changes in dietary patterns is likely low.” 

That’s a big assumption.  Stable weight does not indicate a stable intake of calories, as activity levels and metabolisms often decline over time.  It also doesn’t indicate a stable dietary quality.  People move, jobs change, life happens, and this often impacts our eating style, none of which can be accounted for by this study.

Reverse Causality

This is the concept that people at higher risk for stroke and cardiovascular disease may be more likely to choose to drink ASBs.  Conditions like stroke and heart disease build for years with few or no symptoms.  People drinking the most ASBs were also the LEAST likely to be physically active.  While being sedentary increases the likelihood of all the health risks measured, these individuals may be inactive due to health issues that were not accounted for. 

The Good News and There’s Plenty of It

Controlled intervention studies produce higher quality evidence.  A comprehensive review (Rogers, et al., 2016) of such studies has shown significant benefits from the use of low- and no-calorie sweeteners (LNCS):

• Total calorie intake and body weight are reduced with the use of LNCS when used in place of at least some sugar.
• Use of LNCS does NOT increase desire for sweet foods. 
• No evidence that the use of LNCS undermines weight loss efforts.

It is well-known that healthy weight loss can reduce the risk of cardiovascular disease and stroke.  But, should we place the burden of achieving weight loss and other positive health outcomes on the use or non-use of ASBs?  That seems inappropriate because they were never developed for that purpose.  They have been a lifesaver for diabetics, most certainly, helping them control blood glucose levels while having a satisfactory eating style that helps them feel less deprived.  Indeed, it is accepted that all LNCS have no effect on blood glucose levels and, if used in place of a sugar-sweetened beverage (an ideal use) can help prevent rises in blood glucose levels. 

Careful Spending of Sugar Calories

For diabetics and non-diabetics, LNCS are a tool.  Like every tool, and every food, for that matter, they need to be used wisely.  The real question to anyone considering using LNCS is: How will you, as an individual, not a population, use them?  You can decide if ASBs will be an asset to your eating style.  When I have clinic visits with obese patients who want to lose weight, or just spend fewer calories on sugar, I always go over where their dietary sources of excess calories are.  If they eat a lot of added sugars, these are easy places to focus their efforts.  A simple swap of a calorie-free drink for their usual soda has BEEN SHOWN to reduce total calorie intake.

The lead author states, “We can’t assume these diet drinks are harmless, especially when consumed at high levels,” which is confusing to consumers.  Can we assume ANYTHING, even foods like kale and garbanzo beans, are harmless when consumed at high levels?  Of course not.  On the other hand, more reliable evidence has shown us they can be a beneficial tool.

Finally, my own pet peeve about the potential damage of these observational studies: Since they are not capable of showing cause-and-effect, why do headlines imply there is one?   Such implications are incorrect, irresponsible and are misleading to consumers.

References:

Rogers PJ, Hogenkamp PS, de Graaf C, et al. Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies. Int J Obes (Lond). 2016;40(3):381–394. doi:10.1038/ijo.2015.177

About Dr. Keith Ayoob

Keith Ayoob, EdD, RDN, FAND is an Associate Clinical Professor Emeritus at the Albert Einstein College of Medicine. As a pediatric nutritionist and registered dietitian, Dr. Ayoob is also a past national spokesperson for the Academy of Nutrition and Dietetics.

Dr. Ayoob is a consultant with the Calorie Control Council Advisory Board and the Global Stevia Institute (GSI), GSI is supported by PureCircle Ltd, a global leader in purified stevia leaf extract production.