Ingredient Reviews

Why is sugar not good for you?


When starting my research for this post I was under no illusion that sugar is probably not the healthier ingredient out there but I wanted to delve deeper to understand what exactly the problem with it is. The amount of exaggerated claims and myths about sugar is astounding and it’s important we separate the real dangers from “clickbait” headlines.

For the purposes of this post I am omitting alcohol sugars and dairy sugar (galactose) and focusing on sugars that are widely used as sweeteners. Basically all of these sugars (table sugar aka sucrose, agave nectar, corn sweetener, honey, corn syrup, molasses etc) are a combination of fructose and glucose and are broken down into these two molecules early in the digestion process.

Are natural sugars (i.e. naturally occurring in foods, such as fruit) better than added sugar? The body doesn’t care what particular food it received the sugars from, it processes them exactly the same whether it’s from fruit or from a can of coke. But there are a couple of reasons why natural sugars are healthier for you.

1. From a nutritional standpoint, the food sources in which natural sugars are found (fruit and vegetables) usually contain vitamins, minerals or fiber. It’s unlikely you will find any of these nutrients in sweets and soft drinks. If your intake is, say, 2000 calories a day and 500 of them are from added sugar, you are potentially missing out on the nutrients you would have consumed had you chosen a different source of sugar. So you either become deficient in some nutrients or have to intake extra calories to make up the difference which leads to weight gain.

2. Due to the presence of fiber, fruit take longer to digest, causing a less dramatic spike in blood sugar.

3. Apparently it’s harder to consume too much sugar from natural sources as it usually contains less of it. I actually have my doubts about this one as a can of Coke contains the same amount of sugar as two medium apples. I honestly expected the difference to be much larger.

Sugar has received its fair share of sensational headlines, from being compared to cocaine in its addictive qualities to being discovered as a cause of cancer. When you see headlines like this it’s very important to put your sceptic hat on and try to look at the source data. 99% of the time such “news” is nothing more than a detail taken out of context and blown out of proportions.

When sugar is compared to cocaine, it’s because it causes activation in the same “pleasure centres” of the brain. But so do many other things, like receiving money after completing a task, getting a pleasant surprise, having sex, being shown pictures of your romantic partner, and even learning a new language.
French researchers reported that when rats were allowed to choose between water sweetened with sugar, saccharin or intravenous cocaine, over 90% preferred the sucrose-enhanced water to cocaine. I’m not quite sure what this result is supposed to prove as we know that humans often tend to do the opposite.

Does sugar cause cancer? Most sugars contain glucose which is the main fuel that powers every single one of our cells. The misunderstanding stemmed from the fact that cancer cells also use glucose as fuel but it doesn’t mean that having glucose in the body causes cancer to appear. There’s also no evidence that following a “sugar-free” diet lowers the risk of getting cancer, or boosts the chances of surviving if you are diagnosed. At the same time, high sugar consumption can cause weight gain (as can overconsumption of any other foods, really), and obesity is, indeed, linked to higher risk of getting cancer.

This takes us to the next thing that sugar has been accused of, which is obesity epidemic. While it’s true that eating too much sugar is likely to cause weight gain, this applies to all food in general – if you consume more calories than you expend, you will gain weight. At the moment there is insufficient evidence that an exchange of sugar for non-sugar carbohydrates in the context of a reduced-fat or energy-restricted diet results in greater weight reduction.

And last but not least, let’s look at the connection between sugar and diabetes. First we need to understand what happens in your body when you ingest sugar. As mentioned earlier, sugars are quickly broken down to glucose and fructose, which are then processed differently.

Glucose causes an increase in blood sugar, which triggers release of insulin from the pancreas. Insulin binds to the glucose and transports it to the cells that need energy. When we eat a lot of sugar over a prolonged period of time the pancreas becomes exhausted and unable to efficiently release insulin any longer. This can result in the chronically elevated blood glucose levels. At the same time, glucose is no longer being delivered to the cells that need it, resulting in cell starvation.

Fructose, on the other hand, is metabolised in liver, where most of it is converted to glucose or used to replenish liver glycogen (a form of energy storage). Under 1% is converted to triglyceride (high triglycerides are linked to increased risk of atherosclerosis and heart disease).  In rodents, large amount of fructose stimulates formation of fat and leads to insulin resistance (precursor to type 2 diabetes) and high blood pressure. In humans, fructose consumed in moderate to high quantities increases triglycerides, but does not appear to cause insulin resistance or high blood pressure in the short term. The authors of the review have concluded that further human studies are required to outline the effects of fructose in humans.

It has been considered that moderate fructose consumption of ≤50g/day or ~10% of energy has no deleterious effect on lipid and glucose control and of ≤100g/day does not influence body weight. Another review has concluded that no fully relevant data has demonstrated a direct link between moderate fructose intake and health risks.


So where does this leave us? A lot of articles about sugar talk about “further studies” and “insufficient evidence”. I’m not sure if it’s good news or bad news. On one hand, you’d think that if sugar was that bad, we’d have more defined and consistent results. At the same time, the lack of certainty can create a sense of anxiety when you don’t know for sure how bad something you consume every day is for your health.

Do we actually need sugar? And how much is too much? Our bodies can function perfectly well without any sugar as long as we consume other carbohydrates (such as oats and grains, whole wheat bread / pasta, potato / sweet potato) as they are full of glucose. There is no minimum “healthy” amount of sugar but as per the UK Government guideline it looks like healthy adults can get away with consuming about 90g of sugar (including natural sugars, which are preferable) per day as a part of a balanced diet without negative effects as long as they are watching their total calorie intake.

It might not be easy to stick to this number though as sugars are added to so many foods, such as sauces, low-fat and fat free foods, yogurt, cereal, as well as the usual suspects like cake, chocolate, fizzy drinks, fruit juice etc. Next time you pick these up at the shop read the label to see how much sugar they contain.

~Ellen’s conclusion~

The healthiest option is to avoid sugar, especially non-natural variety, but for the majority of people this is not realistic. If you don’t have any heart or liver problems or any predisposition to diabetes (including being overweight) there is no need to run away in panic when you see sugar. As long as it’s a part of a healthy balanced diet, some sugar can be consumed, preferably from natural sources. For most people, though, that would mean reducing their current sugar intake as many of us are well above the 90g (including natural sugars) recommendation.

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