Sugar is ALL over the news these days and a constant question and misconception in my clinic. This post is going to review the evidence behind...
Let's start with the chemical basics
The term "sugar" actually refers to the chemical structure of the food. Our society also refers to added sugars as a type of food (although they're really called "sweeteners"). Sugar, in the molecular sense, is a type of carbohydrate with a simple chemical structure. It may consist of 1 type of molecule called a monosaccharides (glucose, fructose and galactose) or those single monosaccharides may team up in various combinations to form a disaccharide (sucrose, lactose, maltose). These simple chemical structures mean the body is awesome at turning those molecules into energy.
Our body sees dietary sugar / sweeteners for what they are - chemistry. When you eat white sugar (aka, granulated sugar), the body sees molecules of glucose and fructose which it in turn becomes blood glucose which turns into energy (glucose / fructose --> blood glucose --> energy).
You rarely find a bunch of monosaccharides naturally alone in our food supply (though you can get straight glucose from a lab). Rather, it's more common that you'll find certain foods are rich in monosaccharides (sweeteners, soda) and others contain combinations of mono and disaccharides (fruits, sweeteners, milk).
The same is true for sweeteners / added sugars. Each sweetener is made of a different combination of glucose and fructose (see chart below). This leads people to believe that some sweeteners are superior to others because perhaps they are metabolized differently or create more blood sugar than others...but is that really the case? Keep reading to understand more...
Sweeteners (white sugar, brown sugar, maple syrup, agave etc) are all made from a varying, simple chemistry of fructose and glucose. Our body turns ALL sweeteners into blood glucose which the body uses or stores as energy.
Are some sugars metabolized different than others?
Our bodies break everything down into its simplest form. All disaccharides are turned into monosaccharides before being turned into energy by the body. So at the end of the day, our bodies "see" fructose, glucose, and galactose. (However galactose is rarely found in added sugar / sweeteners - it's typically found in milk. So for the purposes of this writing, I'm only going to focus on fructose and glucose).
However, in contrast to glucose, fructose enters glycolysis (energy production) at a step that bypasses the regulatory control normally exerted by phosphofructokinase. This, in theory, allows unimpeded conversion of excess fructose into cholesterol and triglycerides.
All that being said, the research on whether or not excess fructose makes you gain more body fat and/or increases cholesterol relative to glucose is tough to decipher. Often experiments to establish either of these "facts" are a bit flawed and theoretical because...
The research often demonstrates that eating a TON of EITHER glucose and fructose will result in fat gain and cholesterol, but fructose tends to be ever so slightly higher and the media (and marketers) have pounced on that - demonizing fructose. Here's a decent explanation and example from Precision Nutrition in simple terms exploring one such study.
One additional difference between glucose and fructose is how it affects the gastrointestinal system. For some clients with irritable bowel syndrome (IBS), high amounts of fructose cause the body to pull more water into the GI system causing more diarrhea. For those clients, I may opt for more low fructose, high glucose products whether as an athlete or every day life.
Unless you have an intolerance OR irritable bowel syndrome,
our body generally interacts with fructose and glucose in the same way - one does not cause more metabolic effects than another.
But don't some sugars make MORE blood sugar than others?
Many professionals argue that some sugars are higher on the glycemic index and therefore make MORE blood sugar than others. However that's not the full truth. To understand that you need to understand what the glycemic index is and how it is (and is not) helpful...
HOWEVER, the GI
does NOT take into consideration
what a normal portion size is for a food.
For example, watermelon has GI of 72...but it is based upon consuming 5 cups of watermelon! Similarly, carrots are listed with a GI of 71, but that's based upon eating 1 1/2 lbs of carrots in a sitting.
Realizing the error of their ways, the GI can be translated into the glycemic load (GL). This takes into consideration the portion size AND the amount of carbohydrate in the food giving you a better understanding of how a food will affect blood sugar: Glycemic Load (GL) = GI x Carb (g) / portion ÷ 100
Similarly, it's broken into 3 categories
So if we go back to our examples: Watermelon has a GL of 7.21 (serving size of 1 cup). Carrots have a GL of 6 (serving size of 1/2 cup). The GL is considered additive for the entire meal - meaning if you 2 portions of watermelon and 2 portions of carrots, your GL for the meal is 14+12 or 26.
My point in explaining all of this is that while many argue certain sweeteners have a lower GI than others often fail to take into account, the portion size used of each sweetener. Even if you look at the GL, you see the portion size varies greatly depending on the sweetener used. If you use the SAME portion for each sweetener (for example, 2 Tablespoons), you end up with very similar glycemic effects.
That is why when someone asks me which is better, I honestly reply "portion for portion, they're all the same. what matters is which satisfies you more, with less." For example, while agave appears superior, I find most of my clients use 2-3x as much to get the same level of sweetness for their taste buds. So the effect on blood sugar is virtually identical.
GI is NOT recommended for blood sugar control
in diabetics because there's poor evidence that it helps!
This is because there is incredible variation in how individuals digest and metabolize carbohydrates, combinations of food pairings, physical activity, and degree of insulin resistance...not to mention the "system" itself is pretty complicated to implement. It's far more effective to help clients balance food chemistry ratios and portions (eg, protein, carb, fat) than have them choose brown over white rice.
(Here's a recent nutrition therapy guideline from the ADA. Ctrl + F for "glycemic index").
Portion for portion, all sweeteners create the same amount of blood glucose
So what are "reasonable" amounts?
This is a difficult question to answer. There are a number of guidelines out there (9 to be exact) that offer 12 different recommendations. Most of them (7) don't offer any quantitative guidance. But the others ranged from 5-25% of calories. And get this, the authors state..."The main limitation across all guidelines was the description of expected benefit, or outcomes..."
If you want to check out the systematic review for the quality of the guidelines, CLICK HERE.
Erickson J, Sadeghirad B, Lytvyn L, Slavin J, Johnston BC. The Scientific Basis of Guideline Recommendations on Sugar Intake: A Systematic Review.Ann Intern Med. 2017 Feb 21;166(4):257-267. doi: 10.7326/M16-2020. Epub 2016 Dec 20.
There isn't any research indicating that sugar CAUSES disease. Meaning there's no human research in which we controlled ALL other variables in a person's life and intentionally gave people loads of sugar over an extended period of time to see what happens to their health. Rather, there are a number of observational studies reviewing the CORRELATIONAL nature of sugar and various disease states like diabetes, obesity, cardiovascular disease. But often, those consuming more sugar are also living a very different life.
For example, check out a data snapshot from the CDC (below). It's well documented in the public health literature that chronic disease states are higher in lower income populations. Is there more disease just because they consume more sugar? Or perhaps it's the chronic, toxic stress of living in impoverished circumstances...? Additionally, if they're consuming more sugar, what does that mean for the REST of their food "choices?"
I'm not saying sugar is completely benign and we should all eat a 100% sugar diet. But I am saying that health is about looking at the whole person - not just one nutrient (THIS BLOG post explains more). Cutting out sugar for someone who smokes, is inactive, and living in high stress (eg, working odd hours, multiple jobs, not sleeping enough) may help their health a bit, but the overall circumstance is what's pretty harmful and making sugar a pretty important tool in their life.
Additionally, there is ZERO evidence that eating sugar every day is going to cause harm. For example, I have patients who gasp when I say it's ok to eat dessert every day. But look at it in context - even if you eat 1 cup of ice cream every night, that's 30 grams of sugar (or ~7 teaspoons or 120 calories from sugar). If you're eating 2000 calories per day, that's only 6% of your total energy intake...).
Kind of like saying you spent $6 of your $100 budget on something fun like watching a movie. No you don't "have" to go to the movie and yes you have other places for the money could go, but it's pretty emotionally and socially rewarding- sometimes it's worth the "expense."
There's not enough research to know "how much" sugar is too much or "how much" will cause disease.
Most bodies can tolerate added sugar daily without harm.
What about artificial sweeteners?
Artificial sweeteners are an even more complex topic than sugar sweeteners. There are 2 main categories of artificial sweeteners - sugar alcohols and artificial sweeteners.
At the end of the day, my advice to clients is that the use of artificial sweeteners is personal and up to you. The evidence is mixed about their value in helping with blood sugar or caloric intake. And I cannot say they will or will not cause harm. They are made from a chemical - not necessarily a food. So whether or not you want to use them is based on your beliefs and preferences.
Artificial sweeteners are controversial and a personal choice.
Moral of the story...
This post touched on SO many topics. Here's the brief if I lost you along the way:
Stay nourished friends!
DISCLAIMER: The writing here is for informational and educational purposes only. It is NOT a substitute for individual care. Your needs may vary. or individual support, please contact a provider.
Please note it's been a number of years since I have updated these posts. The content and philosophies may have changed as I've grown as a provider. Please reach out with questions or concerns.
Dietitian, personal trainer, mother, wife, runner, and endurance athlete supporting well-being, one bit and bite at a time