Update 1/9/2024: This post has been updated since we originally published it in September 2021. We’ve updated the research, added in current links, and cleaned up the post. 

In our journey to unveil secrets of human life extension, our inaugural survey, “What are People Eating to Achieve Human Life Extension,” provided pivotal insights. It became clear to me that our audience isn’t one that thinks sugar is particularly healthy for spanners.  

(The same can’t be said of alternative sweeteners.)

At the end of the survey, we asked an open-ended question: “If you were to give an additional single piece of advice to anyone interested in changing their diet for longevity, what would you suggest?”

Of the 101 respondents to the survey, 15 people answered that specific question with a reference to sugar. Here are a few quotes from their responses:

• “You look like your diet. Consider foods, lifestyle, and supplements that enhance your own body’s ability to negate aging. I am 65 in the fall, my hair is still dark, my resting heart rate is 55, I minimize sugars, I don’t do alcohol/drugs/smoke, I’m fairly active.”
• “Limit exposure to sugar, grains, & processed seed oils.”
• “Stop eating sugar!!”
• “Cut the sugar down to an absolute minimum and add lots of plants – in every category – to your diet!”
• “Don’t eat sugar and don’t eat too much.”

In all the diets we covered in our unit on nutrition and life extension, from the Mediterranean diet to the low-carb diet, all uniformly advocated for removing processed foods and refined sugar. 

In other words, I think it’s safe to say that most of our readership is aware that sugar is a problem for people looking to extend their lives. 

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 about in relation to health, nutrition, and aging?

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Why is sugar a nutritional 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—or 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.)

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 endogenouslyGrowing or originating from within an organism. 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. 

Dr. Seema Bonney, the founder and medical director of the Anti-Aging & Longevity Center of Philadelphia, tells me,

“AGEs form when sugar (glucose or fructose) link with the amino acids that are present in collagen and elastin that support the skin.  These form when sugar levels are high, typically from an overconsumption of quick-digesting carbs such [as] sweeteners and refined simple carbohydrates that are void of other nutrients (fiber and protein).”

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 hemoglobinA red protein responsible for transporting oxygen in the blood of vertebrates. Its molecule comprises four subunits, each containing an iron atom bound to a heme group., alkaline phosphataseAn enzyme that liberates phosphate under alkaline conditions and is made in liver, bone, and other tissues., lysozymeAn enzyme that catalyzes the destruction of the cell walls of certain bacteria, occurring notably in tears and egg white., collagenThe main structural protein found in skin and other connective tissues, widely used in purified form for cosmetic surgical treatments. [and] elastinA protein forming the main constituent of elastic connective tissue, found especially in the dermis of the skin..”

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.” In other words, 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 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. 

There are a lot of age-related diseases connected to chronic inflammation. To name just a handful, they include:

• Diabetes
• 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 facts and misinformation, look closely at the relationship between sugar, obesity, and diabetes.

First, let’s start with what diabetes actually is. The CDC summarizes it nicely: 

Most of the food you eat is broken down into sugar (also called glucose) and released into your bloodstream. When your blood sugar goes up, it signals your pancreas to release insulin. Insulin acts like a key to let the blood sugar into your body’s cells for use as energy.

If you have diabetes, your body either doesn’t make enough insulin or can’t use the insulin it makes as well as it should. When there isn’t enough insulin or cells stop responding to insulin, too much blood sugar stays in your bloodstream. Over time, that can cause serious health problems, such as heart disease, vision loss, and kidney disease.

There is no known cure for diabetes, though diabetics can go into remission. Diabetes is the eighth-leading cause of death in the United States as of 2020. 

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. After going through all the research, here’s what I am doing for myself:

• Limit added sugars. I’m female, so I’m looking to consume less than six teaspoons a day. 
• Pass on fructose as much as possible. A whole range of studies indicated that fructose is particularly harmful for aging. 
• Avoid cooking with added sugars (like grilled marinated meats). They are likely to contain AGEs. 
• Pair simple sugars with fiber, along with fat and protein, to help the body digest. Whole foods, like fruit, are an ideal way to consume sugar combined with fiber in a convenient package. 

Sugar and aging are massive topics with a lot of nuance—so much so that I didn’t even get a chance to cover alternative sweeteners. For example, Erika Gray, PharmD, and chief medical officer at toolboxgenomics.com, suggests turning to monk fruit as a sweetener.

What are your takes on sugar? What do you do to avoid them or to add them mindfully to your diet?

Let me know in the comments! 

Rachel Burger

By day, I am a problem solver, writer, and the co-founder of Longevity Advice. I’m best known for writing about technology and have been featured in Forbes, The Hill, and TechRepublic. When the batteries are powered down and the suit comes off, I’m an enthusiastic hiker, runner, and Rocket League competitor and enjoy discussing minimalism, Studio Ghibli, and Icelandic sheepdogs.