Sugars, Food and Health, Why the Source Matters More Than the Sweetness
- Alastair Hunt
- 3 days ago
- 8 min read
Updated: 2 days ago
It’s no secret that excessive sugar intake is a health concern, especially with its links to obesity, diabetes and heart disease. But what if not all sugars are created equal? Many large-scale studies - spanning cohort data, systematic reviews and controlled feeding trials- suggest it’s not just about how much sugar you eat but where that sugar comes from - after all, we eat 'food', be it whole or (increasingly) processed. Let’s break down the evidence to understand which sugars might be problematic and which could even be beneficial.
As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment. Links to all studies at bottom of page.
Free vs. Intrinsic Sugars: A Crucial Distinction
A recent UK Biobank cohort study followed nearly 187,000 people over 12 years to explore how different sugars affect mortality. Free sugars - those added during processing or naturally present in syrups and fruit juices - were associated with an increased risk of death, particularly when they came from sugary drinks like sodas or flavoured milk. Interestingly, the study found that free sugars in solid foods such as cereals, sauces or baked treats did not carry the same risk.
Even more notably, intrinsic sugars - the kind found naturally in fruit, vegetables and dairy - were not associated with any increased risk at all.
Not All Sugar-Rich Foods Affect Metabolic Health Equally
Digging deeper into the metabolic effects of sugar, a second study analysed data from 13 prospective cohort studies to assess the risk of developing metabolic syndrome. Unsurprisingly, sugar-sweetened beverages came out on top as a risk factor. Drinking just one can a day was linked to a 14 percent increase in the likelihood of developing this cluster of conditions that raise your risk of heart disease and diabetes.
However, this wasn't true across the board. Foods like yogurt and whole fruits were actually associated with a reduced risk - by about a third and a fifth, respectively. Even fruit juices, often demonised for their sugar content, showed a more nuanced effect. Small daily amounts, around 125 millilitres, appeared to offer some protection, but this benefit vanished at higher intakes. Note however that 125 ml is very small serving compared to the usual pour.
How Much Fruit Is “Healthy”?
These findings support what many nutrition experts have said for years: whole fruit, in sensible amounts, is good for you. Across the studies, the greatest health benefits were seen when people consumed about three to five servings a day. This level of intake fits well within most national dietary guidelines and doesn’t appear to pose any metabolic or weight-related risks.
In fact, keeping fruit intake within 10 percent of daily calories was consistently associated with neutral or beneficial outcomes - even in studies looking specifically at weight management.
Dried Fruit and Honey: A Matter of Portion Size
Moderation, it turns out, really is key when it comes to dried fruits, which pack in nutrients but also concentrated sugar. Servings in the studies showing benefit were small - roughly 40 to 60 grams a day. And then there's honey, which, despite its sticky-sweet reputation, was linked with modest weight loss in trials where it replaced other sources of sugar. This may be due to its unique composition, which includes rare sugars like allulose and tagatose.
Sugar, Energy Balance, and Weight: What Feeding Trials Show Us
To understand the effects of sugar in real-world eating patterns, researchers looked at 169 controlled feeding trials. These studies examined how different sugar sources affected body weight under various conditions - when they replaced other foods, were added to the diet, or were consumed freely without instructions.
Sugar-sweetened drinks once again showed their downside. When added on top of a regular diet, they led to consistent weight gain. Removing them had the opposite effect: people lost weight, especially if they had been consuming high amounts. But interestingly, when sugars were swapped for other foods in a calorie-matched way, most sweet foods - including fruit, dried fruit and even fruit juice - had little to no impact on body weight. The key factor was not just the sugar but whether it came with extra calories.
The Food Matrix Matters
Why do sugary drinks pose such a risk, while fruit and yogurt don’t? One reason lies in how these foods are digested. Liquids like soft drinks pass quickly through the digestive system, offering little satiety and often leading to overeating. Whole fruits, on the other hand, contain fibre, water, and nutrients that slow digestion and help you feel full.
This is part of what's known as the food matrix effect - the idea that the structure and composition of a food can influence how it's metabolised. Sugars bound up in fibre-rich foods behave very differently from those floating freely in a sweetened drink.
What About “Brain Fog”? Sugar and Cognitive Health
There’s also growing interest in how sugar affects our brains. A major review of 77 studies found strong evidence linking long-term intake of added sugars - especially from sugary beverages - with cognitive impairments like memory problems, reduced attention and even a higher risk of dementia. These effects were seen not only in adults but also in children and prenatal exposure through maternal diet.
However, not all sugars were implicated. In fact, natural fructose from fruits was associated with better cognitive performance in several studies. This could again be due to the protective compounds in fruit, which may buffer the brain against sugar-induced spikes and crashes in blood glucose. While small amounts of glucose can temporarily enhance memory- particularly in older or fasted individuals - regular overconsumption may lead to the very “brain fog” many people seek to avoid. The evidence suggests that fruit helps, while sugary drinks and ultra-processed sweets hinder.
Practical Recommendations
What are your health goals? The nutritional requirements and goals of someone who is dieting for weight loss might be different from an active athlete or person who needs to fuel for a workouts. Below are some of the key findings from the reports...
Whole Fruit
Across the studies, eating three to five servings of fruit per day - roughly 240 to 450 grams - was consistently associated with health benefits, including lower mortality, reduced risk of metabolic syndrome, and even better cognitive performance. This amount fits within standard dietary guidelines and does not increase risk when part of a balanced diet. One serving might be a medium apple, a banana, a slice of melon or a small bowl of berries.
Fruit Juice
For 100% fruit juice, up to 125 to 150 millilitres per day - about half a small glass - was found to be neutral or beneficial in terms of metabolic and cognitive health. Beyond this amount, the benefits flatten or reverse, likely due to the lack of fibre and the concentration of free sugars. If you're including juice, it's best consumed with meals rather than on its own.
Dried Fruit and Honey
Moderate amounts of dried fruit (around 40 to 60 grams per day) were linked to either neutral or modestly beneficial effects on weight. Similarly, up to 50 grams of honey per day showed some promise for modest weight reduction in trials, possibly due to its unique sugar composition. These should be treated as supplements to, not replacements for, whole fruit.
Sugar-Sweetened Beverages
The clearest advice from all studies is to minimise or eliminate sugary drinks like sodas and sweetened milk beverages. These were consistently associated with increased risks across all health outcomes - mortality, metabolic syndrome, weight gain, and cognitive decline.
Recently there has been some online fear mongering about glucose 'spikes' from consuming fruit, muesli and blended fruit smoothies. We address both these issues in detail, learn more here on fruit and muesli; and here on smoothies.
Final Thoughts
While sugar continues to be a public health concern, multiple studies show that blanket recommendations to avoid all sugars may miss the mark. It's not just the sweetness- it's the source, context and how much you're consuming. Sugary drinks remain a clear target for reduction but whole fruits, modest amounts of fruit juice can still fit within a healthy diet. The food matrix, portion size, and total energy balance all matter more than sugar content alone.
So next time you reach for something sweet, consider not just the sugar it contains - but the company it keeps.
Changing health for the better is about progress, not perfection, and even small changes can have a powerful and positive effect on health. For most people, improving health is about finding motivation and prioritising self-care - with an ultimate goal of taking action. If you want to take effective and targeted steps that fit into your unique lifestyle and circumstances, The Whole Health Practice is here to help.
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Stay Healthy,
Alastair
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Related Studies and Resources
Chiavaroli L, Cheung A, Ayoub-Charette S, Ahmed A, Lee D, Au-Yeung F, Qi X, Back S, McGlynn N, Ha V, Lai E, Khan TA, Blanco Mejia S, Zurbau A, Choo VL, de Souza RJ, Wolever TM, Leiter LA, Kendall CW, Jenkins DJ, Sievenpiper JL. Important food sources of fructose-containing sugars and adiposity: A systematic review and meta-analysis of controlled feeding trials. Am J Clin Nutr. 2023 Apr;117(4):741-765. doi: 10.1016/j.ajcnut.2023.01.023. Epub 2023 Feb 23. PMID: 36842451.
Kaiser A, Schaefer SM, Behrendt I, Eichner G, Fasshauer M. Association of all-cause mortality with sugar intake from different sources in the prospective cohort of UK Biobank participants. Br J Nutr. 2023 Jul 28;130(2):294-303. doi: 10.1017/S0007114522003233. Epub 2022 Oct 7. PMID: 36204988; PMCID: PMC10277665.
Semnani-Azad Z, Khan TA, Blanco Mejia S, de Souza RJ, Leiter LA, Kendall CWC, Hanley AJ, Sievenpiper JL. Association of Major Food Sources of Fructose-Containing Sugars With Incident Metabolic Syndrome: A Systematic Review and Meta-analysis. JAMA Netw Open. 2020 Jul 1;3(7):e209993. doi: 10.1001/jamanetworkopen.2020.9993. PMID: 32644139; PMCID: PMC7348689.
Ramne S, Alves Dias J, González-Padilla E, Olsson K, Lindahl B, Engström G, Ericson U, Johansson I, Sonestedt E. Association between added sugar intake and mortality is nonlinear and dependent on sugar source in 2 Swedish population-based prospective cohorts. Am J Clin Nutr. 2019 Feb 1;109(2):411-423. doi: 10.1093/ajcn/nqy268. PMID: 30590448.
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