People looking to extend their lives have a particular interest in sugar and aging, but what does the science actually say?
This article is a repost which originally appeared on Longevity Advice Rachel Burger - September 13, 2021 Edited for content and readability Images sourced from Pexels
In a lot of diets, from the Mediterranean diet to the low-carb diet, all uniformly advocated for removing processed foods and refined sugar.
But mechanistically, why is sugar a problem? Does sugar contribute to aging? Are there nuances to the sugar-is-always-bad narrative?
In this article, I aim to answer all these questions. But first, I want to address a larger question: why is sugar talked so much in relation to health, nutrition, and aging?
Why is sugar a focus?
Humans are hardwired to love sweet foods.
You might meet the occasional adult who claims to hate sugar, but you’ve likely never met a kid who turned their nose up at a sweet. In fact, there’s a general consensus that sugar preferences in children are not a byproduct of advertising or food manufacturing, but of biological desires. A review published in the journal Clinical Nutrition and Metabolic Care explains, “Heightened preference for sweet-tasting foods and beverages during childhood is universal and evident among infants and children around the world.”
While “too sweet” is a concept adults are familiar with (they tend to max out at about what you’d get in a 20 oz Gatorade), there is no known upper limit to how much sweetness—sugar, by extension—kids like.
“Sugar” is shorthand for “simple carbohydrates.” There are two natural categories of sugars:
- Monosaccharides: Simple carbs with a single sugar molecule. Glucose, fructose, and galactose are monosaccharides.
- Disaccharides: Simple carbs with two sugar molecules joined together.
There are only three disaccharides that are naturally occurring. Sucrose, which you can find in table sugar, honey, and dates, is a combination of glucose and fructose. Lactose, or the combination of glucose and galactose, is natural milk-derived sugar, found in cream, butter, and human breast milk. Finally, there’s maltose, which has two bonded glucose molecules, which is found in germinating grains. Foods with maltose include beer and bread.
(Other sweeteners, like high fructose corn syrup, are man-made disaccharides [any of a class of sugars whose molecules contain two monosaccharide residues].)
Carbohydrates, regardless of if they’re simple or complex carbs, are used for four functions in the human body. As this is an incredibly dense topic, please use the links provided for further reading if you’re interested.
- Producing energy: Most human cells prefer or require carbohydrates to produce energy and work as they’re supposed to.
- Energy storage: Carbohydrates that aren’t immediately used are stored as glycogen.
- Building macromolecules: Carbohydrates are used to make ribose and deoxyribose, the foundations of macromolecules like DNA and RNA.
- Preserving fat and protein: Blood glucose spares the body from having to use fat and protein as the body’s main source of energy.
In other words, carbohydrates are an essential part of a functioning human body. Because simple carbs have a shorter chain of molecules, they’re easier to digest in the body. Over email, Julie Olson, BSc., CN, BCHN, CGP, of Fortitude Functional Nutrition, elaborates: “Carbohydrates are a main source of energy, converted by the body to power our cells. We need some sugar for some brain cells, some kidney cells, red blood cells, and testes cells” to function properly.
Simple carbs are a subject of conversation in nutritional circles because humans generally rely on carbohydrates to function, and humans particularly like sugar and its sweetness.
Unfortunately, our preference for sweets has led to an excess of added sugar in the Western diet.
Added sugar versus natural sugars
When I say “added sugar,” I mean simple carbs that have been mixed into foods during food processing. Natural sugars, by contrast, are simple sugars found in whole foods, like sugars found in fruits and vegetables.
Some sugars found in nature, like honey and maple syrup, are also considered added sugar.
The American Heart Association recommends consuming no more than 100 calories, or six teaspoons, of daily added sugars for females and children. Males can consume up to nine teaspoons, or 150 calories, of added sugars daily.
Unfortunately, the average American consumes 17 teaspoons of added sugar every day—that’s a 183% increase and an 89% increase from recommended daily intake for females and males, respectively.
And that excess sugar consumption has huge health consequences.
Sugar and aging
Added sugar increases the rate of biological aging. It does so in several ways. In 2018, the Annual Review of Nutrition published a systematic review of longitudinal studies on the correlation between high sugar consumption and cancer. They produced an infographic that aptly demonstrates just how much of the body added sugar ages and points to mechanisms as to why it does so:
This next section will drill down into three documented ways sugar and aging are intertwined: AGEs, inflammation, and diabetes. I’ll also cover a quick study on sugar’s effect on telomeres at the end.
Sugar and aging: a close look at AGEs
Let’s talk a bit about “advanced glycation end products,” or AGEs. AGEs are a diverse group of molecules that build up in human cells, particularly in muscle tissue and plasma. They’re created as a reaction between glucose and the amino acid glycine—when sugar meets fat or protein in the body. AGEs have a particularly resistant structure to degradation.
Emerging research suggests that AGEs form at an even higher rate with fructose than glucose—sweeteners like high fructose corn syrup, apple juice, honey, molasses, caramel, and agave syrup all contain fructose.
In other words, AGEs make your skin appear dry, saggy, and wrinkled—old. While AGEs age your insides, they also quickly age your exterior as well.
Diet is a major source of AGEs—barbecued meats, in particular, are full of them. They can also form while humans metabolize their food. AGEs formed in vivo tend to particularly affect “long-lived proteins, such as , , , [and] .”
There’s a general consensus in the scientific community that accumulated AGEs “are an inevitable component of the aging process in all eukaryotic organisms, including humans.” The more you have, the quicker you age.
Here’s why AGEs are a problem in large quantities: they’re linked to diabetes, cardiovascular disease, and renal disease. They’re also connected to Alzheimer’s disease and kidney disease. A whole host of studies demonstrate that AGEs trigger oxidative stress and excessive reactive oxygen species (which also cause oxidative stress).
Sugar and aging: chronic inflammation
Inflammation is a biological defensive response to an irritant, like bacteria or viruses. If you skin your knee, the area around the cut will inflame, as a part of your immune system, to combat infection and to promote healing. Concentrations of white blood cells cause inflammation.
Inflammation can be short-term, or “acute.” If you’re like me and allergic to hay, your body will have an acute inflammatory response—an itchy, watery nose, a puffy face—until the irritant goes away. Inflammation can also be long-term, or “chronic,” and you can stay inflamed regardless if the trigger is still present.
- Cardiovascular diseases
- Arthritis and joint diseases
- Chronic Obstructive Pulmonary Disease (COPD)
- Certain kinds of cancer
Chronic inflammation can also help form AGEs.
Several studies have established that sugar, in all its forms, correlates with inflammation. Some studies have found that fructose appears to cause the most inflammation out of all of sugar’s forms, but that hasn’t been a consistent finding across all studies.
While it’s a mystery why some inflammation remains acute and other inflammation becomes chronic in some people and not others, sugar consumption is a significant precursor to chronic inflammation in many people.
Sugar and aging: diabetes
If you want to see a complicated cocktail of fact and misinformation, look closely at the relationship between sugar, obesity, and diabetes.
Obesity is also a chronic disease. Obesity is defined as having a BMI, or a person’s weight in kilograms divided by the square of height in meters, of 30.0 or higher. According to Harvard Medical School, there are “genetic, developmental, hormonal, environmental, and behavioral factors” that contribute to who does and doesn’t have obesity.
Like diabetes, there are many treatments for obesity, but no known cure. One study suggests that if trends continue, all American adults will be either overweight or obese by 2048.
I choose to mention obesity and diabetes together because they have a significant causal relationship—obesity is an independent risk factor that can lay the groundwork for diabetes to develop. Almost all (89%) of people with diabetes are obese or overweight. I found a massive range of estimates of how many obese individuals develop diabetes, from 2.9% to 30%. Many of the studies cited here look at both obesity and diabetes together as comorbid conditions. For example, hypertrophic obesity—what happens when fat cells enlarge more than normal—directly leads to insulin resistance.
Researchers have formally tied added sugar consumption to obesity and diabetes several times over. Though the relationship is complex and researchers don’t fully understand all mechanisms involved, it’s clear that added sugar consumption, particularly fructose, raises the risk of developing obesity and diabetes.
For example, foods high in fructose stimulate ghrelin while suppressing leptin—hormones responsible for hunger and satiety. Sugar can promote chronic hyperglycemia, which can both lead to weight gain and is another risk for diabetes. And sugary drinks, especially, are tied directly to obesity.
Sugar and aging: a bad combination (so what should we do?)
People looking to stay young for a long time should limit their sugar consumption. While how added sugar works in the body isn’t simple or predictable, there are literally thousands of studies tying added sugar to diseases of aging.
With all that said, it’s natural for humans to crave and eat limited amounts of sugar.
Sugar and aging is a massive topic with a lot of nuance—so much so that I didn’t even get a chance to cover alternative sweeteners.
What are your takes on sugar? What do you do to avoid them or to add them mindfully to your diet?