Sugars

Sugars are carbohydrates made of one or two sugar units. EFSA, the EU’s food safety agency, lists seven main ones in mixed diets. Glucose, fructose and galactose are single sugars; sucrose (table sugar), lactose (milk sugar), maltose and trehalose are double sugars.

Each of the six common ones has its own page: glucose, fructose, galactose, sucrose, lactose and maltose. This page is the overview, and it keeps single-sugar detail short.

The word “sugar” hides four different ideas, and the health advice depends on which one is meant. The table below sorts them out. In short, the WHO limit applies to free sugars. Those include the sugar in honey, syrups and fruit juice, but not the sugar in a whole apple.

Most readers do not know how far past the limits typical intakes are. In the national US survey, added sugar supplied 14.9% of calories on average in 2005 to 2010. And 71.4% of adults took in 10% or more.

This page sets out what 34 studies and reports show, at their real evidence level. They cover teeth, weight, diabetes, the heart, the liver, sugar taxes and the history of industry funding.

Term	What it covers	Who uses it
Total sugars	All single and double sugars in a food, whatever their source. EU rules count all monosaccharides and disaccharides in food and leave out polyols (sugar alcohols). FDA rules define total sugars as the sum of all free mono- and disaccharides, such as glucose, fructose, lactose and sucrose.	EU label rules, FDA, EFSA
Natural (intrinsic) sugars	Sugars inside intact fruit, vegetables and milk. This is not a separate line on a label. The WHO guideline does not refer to the sugars in fresh fruits and vegetables or in milk.	WHO
Added sugars	Sugars added to food as an ingredient during processing or cooking, or eaten alone or added at the table. The FDA label rule also counts sugars from syrups and honey, and sugars from concentrated fruit or vegetable juice beyond what the same volume of 100% juice would hold.	EFSA, FDA
Free sugars	Added sugars plus the sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates. This is the group the WHO limit covers.	WHO, EFSA

Health effects of sugar

• ★★★Weight gain from sugary drinks in adultsIn adults, adding sugary drinks led to 0.83 kg more weight gain, and taking them out cut weight by 0.49 kg. A WHO review found weight fell by 0.80 kg when adults ate less free sugar and rose by 0.75 kg when they ate more.
• ★★Tooth decay goes with sugar intakeEFSA, the EU food safety agency, calls sugar intake a well-established hazard for tooth decay. A WHO review of mostly observational studies found less decay when free sugars stayed under 10% of energy.
• ★★Raised blood fats and blood pressureIn 39 trials, more free sugar raised triglycerides, a blood fat (by 0.11 mmol/L), and LDL “bad” cholesterol (by 0.12 mmol/L). In trials of 8 weeks or more, the top blood pressure number was higher (6.9 mm Hg systolic).
• ★★No clear effect on children’s behavior or thinkingIn 23 blinded studies, children given sugar and children given a sweetener placebo did not clearly differ on 14 measures. The authors say a small effect cannot be ruled out.
• ★★Extra fructose calories raised liver fatIn healthy adults, 7 of 13 small trials found that swapping in fructose at equal calories did not change liver fat. The other 6 added 21 to 35% extra energy as fructose, which raised liver fat, perhaps through the extra energy.

Foods high in sugars

Whole fruit leads our USDA ranking, and honey is the one concentrated sweetener in it. Per serving, dates are first with 31.9 g in 2 dates (48 g). Then come grapes (23.4 g in 1 cup) and mango (22.5 g in 1 cup). Cherries, apples and pears follow, and honey gives 17.2 g in 1 tbsp; the ranking below has every amount.

Per 100 g the order changes: honey has 82.1 g and dates 66.5 g, far ahead of figs, grapes, mango, cherries and bananas. Honey looks small per serving only because a tablespoon is small.

Our ranking counts total sugars. It cannot tell added sugars from the natural ones inside a fruit, and that matters. The sugar in a whole piece of fruit is outside the WHO guideline, while the sugar in juice and honey is inside it.

Most added sugar in the United States does not come from fruit. In the national survey behind the 2020 to 2025 Dietary Guidelines, sugar-sweetened beverages gave the largest share (24%). Desserts and sweet snacks gave 19%, sweetened coffee and tea 11% and candy 9%. The chart in “How sugars work” shows all of them.

How sugars work

Most of what is known about how the body handles sugars comes from physiology and chemistry. Human studies cover the health outcomes on the cards above. Four ideas cover it.

Sugars are one or two sugar units. Enzymes and carriers in the gut move them into the blood, and the liver takes up most fructose and turns galactose into glucose. In the mouth, bacteria turn sugars into acid. Energy, more than any special sugar effect, ties the rest together.

Sugars are one or two sugar units

Carbohydrates are grouped by chain length. Sugars have one or two units, short chains of 3 to 9 units are oligosaccharides, and chains of 10 or more are polysaccharides. That group includes starch and the non-starch polysaccharides behind fiber.

Sugars are digested in the small intestine, except lactose in people with low lactase activity. Food labels count them at 4 kcal per gram.

Glucose and fructose are common in fruit, berries, some vegetables and honey. Sucrose comes from sugar cane and sugar beet, and is also in many fruits and vegetables. Lactose is found only in milk and dairy, and maltose in germinating grain and glucose syrups.

Enzymes split double sugars and carriers move single sugars

Enzymes on the gut lining cut double sugars into single ones, and the cells lining the small intestine take those up. Glucose and galactose enter through a carrier called SGLT1, and fructose through a different one, probably GLUT5. They leave toward the blood through GLUT2 and GLUT5.

Mutations in SGLT1 cause a major defect in glucose and galactose absorption. The result is severe watery diarrhea that is fatal if untreated, which shows how much the body depends on that carrier.

Genetic sucrase-isomaltase deficiency shows the same for the enzyme that digests sucrose. It was once thought to be a rare condition of infants. But it can also appear later in life, with symptoms that overlap irritable bowel syndrome.

The liver takes up most fructose and converts galactose

Fructose is almost completely taken up by the liver, which quickly turns it into glucose, glycogen, lactate and fat. This fits what is seen in people: a lot of fructose can raise blood fats while hardly moving blood glucose.

A review judged that very high fructose intake can harm humans as it does rodents, and that evidence for moderate doses is weak. It found no direct evidence that high-fructose corn syrup does more harm than sucrose.

Galactose is almost completely converted into glucose in the liver by a four-enzyme route, the Leloir pathway. A defect in it causes galactosemia.

Mouth bacteria turn sugars into acid

Plaque bacteria break dietary sugars down to organic acids, and the acids dissolve tooth enamel and dentine. EFSA calls this mechanism well established.

Sucrose also helps build plaque, and there is some evidence that it causes more decay than other sugars. But EFSA found too little evidence to rank sugars, or to say that swapping one for another would help.

The Vipeholm study suggested the pattern of eating matters. Sticky sugary foods between meals caused a lot of decay, while non-sticky sugar at meals had little effect in that supervised group.

Excess energy is the main route to weight

EFSA names excess energy and weight gain as the main way dietary sugars may contribute to chronic disease in free-living people. The review of weight trials fits that. Swapping sugars for other carbohydrates at the same energy did not change body weight (0.04 kg). Eating freely with less or more sugar moved weight by about 0.8 kg.

Mechanisms specific to sugars may also play a role when energy balance is positive. Examples are making fat in the liver, insulin resistance in the liver and higher uric acid.

What has been seen in people

In the United States, sweetened drinks are the biggest single source of added sugar, ahead of desserts, coffee and tea. The chart puts the sources on one scale.

Intakes in surveys sit above most official limits. The next chart puts the limits and the measured intakes side by side.

Putting the cards together: sugar is clearly linked to tooth decay. Sugary drinks cause weight gain in trials, and are linked to diabetes and a higher risk of death in cohorts. Trials show higher triglycerides and blood pressure with more sugar, and small trials show less liver fat when free sugar is cut.

For total sugar in mixed foods, and for whole fruit, the cohort evidence is weaker or points the other way. Most trials tested drinks or whole diets, not a single sugar. Several had food-industry funding or industry-linked authors, which we flag on the cards.

How much sugar is too much?

No daily amount of sugar is needed from food, and no authority has set a safe upper level. The WHO advises under 10% of energy from free sugars, with a conditional further cut to under 5%. On a 2,000 kcal day that is about 50 g and 25 g (our arithmetic).

The current US Dietary Guidelines (2025 to 2030) say no amount of added sugars is recommended. They add that one meal should contain no more than 10 g of added sugars. The previous edition (2020 to 2025) said under 10% of calories from added sugars from age 2.

EFSA could set no upper level and advises added and free sugars “as low as possible” within a nutritionally adequate diet.

Source	Group	Value	Notes
WHO 2015	Adults and children	Free sugars: under 10% of total energy (strong recommendation); a further reduction to under 5%, roughly 25 g (6 teaspoons), is conditional	About 50 g and 25 g on 2,000 kcal. The guideline does not refer to sugars in fresh fruits and vegetables or in milk.
US Dietary Guidelines 2025 to 2030 (current)	General advice; infancy and early childhood	No amount of added sugars is recommended or considered part of a healthy diet; one meal should contain no more than 10 g of added sugars; avoid added sugars in infancy and early childhood	Also advises avoiding sugar-sweetened beverages such as sodas, fruit drinks and energy drinks, and limiting low-calorie non-nutritive sweeteners. Sugars naturally in fruit and plain milk are not counted as added sugars.
US Dietary Guidelines 2020 to 2025 (previous edition)	Age 2 and older; under age 2	Added sugars: under 10% of calories a day from age 2; avoid foods and beverages with added sugars under age 2	About 50 g on 2,000 kcal. The guidelines note that most Americans have less than 8% of calories left for added sugars after meeting food group needs in nutrient-dense forms.
FDA	Food labels	Daily Value for added sugars: 50 g. No Daily Value for total sugars	Labels show “Includes X g Added Sugars” under Total Sugars. The Daily Value predates the 2025 to 2030 guidelines and still applies to labels.
EU Regulation 1169/2011	Adults, labels	Reference intake for sugars: 90 g a day	A labeling reference for all sugars, not a target. As listed in the intake table above.
EFSA 2022	General population	No tolerable upper level or safe level could be set; added and free sugars “as low as possible”	Across European surveys, the lowest and highest adult means were 6 to 15% of energy for free sugars and 5 to 10% for added sugars.
UK SACN 2015	Population, age 2 and older	Free sugars: no more than 5% of dietary energy	About 25 g on 2,000 kcal (our arithmetic).
National Academies 2005	Adults	Suggested upper limit for added sugars: 25% of energy	About 125 g on 2,000 kcal (our arithmetic). Suggested because some US subgroups above this level had micronutrient intakes below the DRI; the Institute found the data too thin to set a tolerable upper level.
American Heart Association 2009 and 2017	Women and men; children age 2 and older	Most women no more than 100 kcal and most men no more than 150 kcal a day from added sugars; children no more than 25 g, none under age 2	100 kcal is about 25 g and 150 kcal about 37.5 g (our arithmetic).

Typical intakes are above these limits. US adults took in 14.9% of calories from added sugar on average in 2005 to 2010. In the 2020 to 2025 guidelines (the survey data behind the previous edition), added sugars supply more than 13% of calories. That is about 266 kcal a day across the population.

In Europe the mean adult intake of free sugars ranged from 6% to 15% of energy across surveys. Sugary drinks, sweets, desserts and coffee and tea with sugar carry most of it, so those are the first place to look.

Sugar has no deficiency state to describe. The 130 g carbohydrate RDA (recommended dietary allowance) of the National Academies covers carbohydrate from any source. We found no deficiency disease linked to eating no added sugar, so this page has no deficiency section.

Forms of sugar: absorption and effects

Sugar comes as table sugar, brown sugar, syrups, honey, juice and whole fruit. Chemically, most of them are mixtures of glucose and fructose. The head-to-head trials that exist found small differences between them, next to the amount eaten and what the sugar comes in.

The WHO counts honey, syrups, fruit juice and fruit juice concentrates as free sugars. The FDA counts syrups, honey and juice concentrates as added sugars, so none of them is outside the limits.

Where trials exist the doses are large. They include 50 g of carbohydrate a day from honey, sucrose or high-fructose corn syrup (HFCS) for 2 weeks. Another gave 10 to 25% of energy as HFCS drinks for 2 weeks, and another 5% of calories from maple syrup for 8 weeks.

We found no trial showing honey, maple syrup, brown sugar or agave beat sugar for a hard outcome such as diabetes or heart attack. Studies of fruit juice and whole fruit are mostly cohorts.

Form	What it is	What studies show	Source
Table sugar (sucrose)	One glucose and one fructose unit joined; made from sugar cane or sugar beet	In a 2-week crossover trial it had effects similar to honey and HFCS55, and all three raised triglycerides. In cohorts, higher sucrose intake went with a lower risk of type 2 diabetes (risk ratio 0.89), which cannot show cause.	1, 4, 5
Brown sugar	A sweetener sold as an alternative to refined white sugar	One lab assay put its antioxidant capacity between 0.2 and 0.7 mmol FRAP per 100 g, far above refined sugar (under 0.01). We found no trial of brown against white sugar for any health outcome.	8
Honey	Bee-made syrup, a free sugar under WHO and EFSA definitions; 82.1 g of sugars per 100 g in our ranking	A meta-analysis of 18 trials found small gains in fasting glucose and blood fats, with low certainty. A direct 2-week trial against sucrose and HFCS55 found similar effects. “Honey is healthier than sugar” is only partly supported.	2, 4, 6, 17
Maple syrup	Tree-sap syrup, a free sugar	One 8-week crossover trial of 42 adults found a slightly lower glucose response and systolic blood pressure than sucrose syrup. It is the only trial we found.	2, 7
Agave syrup	Syrup from agave sap, described as fructose-rich	Almost no antioxidants in the lab assay. In 18 mice it gave less weight gain and lower glucose than sucrose. A 2022 review says more research on human metabolism is needed to back health claims. We found no human trial against sugar.	8, 9, 10
High-fructose corn syrup (HFCS)	A glucose and fructose liquid sweetener; HFCS55 has 55% fructose	Similar to honey and sucrose in a 2-week trial. In young adults, drinks at 10%, 17.5% and 25% of energy raised triglycerides and uric acid in steps. Reviews found no direct evidence that it does more harm than sucrose.	4, 11, 12, 13
Fruit juice concentrate	Concentrated juice used as a sweetener	Counted as free sugar by WHO and EFSA, and as added sugar by the FDA when it exceeds what the same volume of 100% juice would hold. We found no trial of juice concentrate as a sweetener alone.	1, 2, 3
100% fruit juice	Juice from fruit, with no sugar added	In cohorts, a daily serving went with a higher BMI change in children and, in adults, with weight change that depended on whether energy was adjusted. It went with a higher diabetes risk in two cohort analyses (hazard ratio 1.08 per 3 servings a week; 7% per daily serving after adjusting for body fat).	14, 15, 16
Whole fruit	Sugar inside intact fruit, outside the WHO guideline	Total whole fruit went with a slightly lower diabetes risk (hazard ratio 0.98 per 3 servings a week). Blueberries, grapes and apples were lower, cantaloupe higher.	2, 15

Here are the form-specific studies, strongest evidence first, seven in all.

Is sugar bad for you? Limits and who should watch it

Sugar in the amounts found in whole foods is not a safety problem for most people. An American Heart Association (AHA) statement on children says added sugars can most likely be safely eaten in low amounts in a healthy diet. The concern is the amount, and above all the form.

No authority sets a tolerable upper level. EFSA could not find an intake at which the risk of tooth decay or chronic disease is not raised, across the range people eat. It advises added and free sugars as low as possible.

• Teeth. Sugar is the one clearly established cause on this page. Cavity risk depends on how often and how long teeth are exposed. A 1989 review of the Vipeholm study notes that sticky sugary foods between meals are the highest risk. The EU’s tooth-mineralization claim applies to replacing sugar, in foods that do not lower plaque pH below 5.7.
• Sugary drinks. They are the form with the most evidence of harm: weight gain in trials, and higher diabetes and death risk in cohorts. EFSA rates the certainty as high for obesity, type 2 diabetes, high blood pressure and cardiovascular disease. But diet drinks showed similar links to the last two.
• Inherited sugar disorders. In hereditary fructose intolerance, fructose, sucrose and sorbitol cause low blood sugar and vomiting. Untreated cases can lead to liver and kidney failure, and honey, agave syrup, HFCS and molasses are on the avoid list. In classic galactosemia, infants need a lactose-restricted diet; started in the first ten days of life, it usually prevents the severe early complications. Inherited sucrase-isomaltase deficiency and glucose-galactose malabsorption also limit specific sugars. Families should follow their metabolic team.
• Diabetes, fatty liver and children. If you have diabetes or liver disease, ask your care team how to fit sugars into meals. The current Dietary Guidelines say to avoid added sugars in infancy and early childhood. The AHA statement for children recommends no more than 25 g of added sugars a day from age 2, and none before age 2. One small trial in boys with fatty liver found liver fat fell when free sugar was cut sharply.
• Sugar substitutes. The 2025 to 2030 Dietary Guidelines advise limiting low-calorie non-nutritive sweeteners as well as added sugars. The previous edition said they may cut calories in the short term, but left questions about long-term weight control. In the diabetes cohort analysis, diet drinks and juice were unlikely to be healthy swaps for sugary drinks, though the findings involved bias.

How to eat less sugar

• Start with drinks. The 2025 to 2030 Dietary Guidelines say to avoid sugar-sweetened beverages such as sodas, fruit drinks and energy drinks. They say to choose water and unsweetened drinks. Sweetened drinks were 24% of US added sugars in the earlier survey. In adults, taking them out gave 0.49 kg of weight loss in trials.
• Read the label for added sugars. A US label lists “Includes X g Added Sugars” (Daily Value 50 g), and syrups, honey and concentrated juice count. The current Dietary Guidelines add: look for names with “sugar” or “syrup” or ending in “-ose”. On an EU label the sugars line is total sugars, so check the ingredient list for syrups and honey.
• Keep whole fruit, cut sweet extras. The WHO guideline leaves out the sugar in fresh fruit, and whole fruit was linked to slightly lower diabetes risk. Desserts and sweet snacks supply 19% of US added sugar, so they are the next place to cut.

History of sugar research

The Vipeholm dental caries study, reported in 1954, followed 436 people for five years while the amount and form of their carbohydrate intake was varied. Its main finding is generally accepted: sugary foods eaten in a sticky form often between meals cause a lot of tooth decay. The study has also been criticized on ethical grounds.

Early warning signs of a heart-disease risk from sucrose appeared in the 1950s. Cristin Kearns and colleagues analyzed documents from the sugar industry. They show that in 1965 the Sugar Research Foundation paid for a literature review in the New England Journal of Medicine. The review played down sucrose and pointed to fat and cholesterol, and the funding was not disclosed.

The same group found that the foundation ended an animal project on sugar and blood fats (Project 259, 1967 to 1971) without publishing its results. And when the US dental institute planned its 1971 National Caries Program, 78% of the sugar industry’s submission was written into the call for research.

In 1976 the US Sugar Association won a public-relations award for a campaign that, the authors say, limited the spread of policies to restrict sugar. Funding still shapes the field. A 2013 review found that reviews of sugary drinks and weight were five times likelier to find no link when the authors had industry conflicts.

Sugar is now in most of the food supply. A 2016 analysis reported that 74% of products in the US food supply contain caloric or low-calorie sweeteners.

Policy has moved. The WHO published its free sugars guideline on 4 March 2015, and US labels now list added sugars. EFSA’s 2022 opinion, requested by five Nordic countries in 2016, found no safe level. Most of the evidence on this page is newer than the debate it follows.

Frequently asked questions about sugars

Is natural sugar better than added sugar?

Not as molecules, but the food around them matters. The WHO guideline does not refer to sugars in fresh fruits and vegetables or in milk, because no adverse effects have been reported for them. In three US cohorts, every 3 weekly servings of whole fruit went with a hazard ratio of 0.98 for type 2 diabetes, juice 1.08. Honey, syrups and juice are free sugars, so they count toward the limit.

Does sugar cause diabetes?

Sugary drinks are linked to it: across 17 cohorts, each daily serving went with 13% higher risk after adjusting for body fat. Sugar in general is less clear: across 15 cohorts, total sugars were not linked (risk ratio 0.91). EFSA rates the certainty as low for added and free sugars and type 2 diabetes in trials, and high for sugar-sweetened beverages in cohorts. Extra energy and weight gain look like the main route.

Does sugar make children hyperactive?

Not in blinded studies. A meta-analysis of 23 studies found no effect of sugar on behavior or thinking, with the confidence interval for all 14 measures including zero. The authors suggest parents’ strong belief may come from expectation, though a small effect, or an effect in some children, cannot be ruled out.

Is sugar addictive?

A 2016 review found little evidence for sugar addiction in humans. Bingeing in animals appeared with intermittent access to sweet or very tasty food, rather than from sugar’s effects on the brain’s chemistry. The authors argue against adding sugar addiction to policy until there is better evidence.

Is honey or brown sugar healthier than white sugar?

At best only slightly. In a 2-week trial, 50 g of carbohydrate a day from honey, sucrose or HFCS55 had similar effects, and all three raised triglycerides. A meta-analysis of 18 trials found small gains in fasting glucose and blood fats with honey, on low-certainty evidence. Brown sugar had more antioxidant capacity than refined sugar in a lab assay, but we found no trial of it. All of these count as free or added sugars.

Is fruit juice as bad as soda?

Not quite, but it is not a free pass. Per daily serving, sugary drinks went with 13% higher diabetes risk after adjusting for body fat, and fruit juice with 7%. In children each daily serving of 100% juice went with a 0.03 higher BMI change, against 0.07 kg/m² for sugary drinks. In cohort studies, EFSA found moderate certainty that fruit juice raises the risk of type 2 diabetes, and high certainty for sugary drinks.

Do sugar taxes work?

They reduce purchases of taxed drinks: a WHO-commissioned review of 62 studies found a 15% fall in sales, with no clear switch to untaxed drinks. A smaller review put a 10% tax at a 10% fall in purchases and intake. After England’s soft drinks levy, obesity fell by 1.6 percentage points in 10-to-11-year-old girls but not in boys or younger children. Other changes at the time cannot be ruled out.

What does “added sugars” on a label mean?

It means sugar put in during processing or packed as an ingredient. The FDA rule counts syrups, honey and the sugars of concentrated fruit or vegetable juice beyond what 100% juice would hold. US labels show it under total sugars as “Includes X g Added Sugars”, with a Daily Value of 50 g. EU labels give total sugars, with an EU Reference Intake of 90 g.