Sugar, a risk factor for cancer?

Consuming too much sugar is bad for your health, it is now a well-documented fact. Too much sugar, especially sugary drinks, increases the risk of tooth decay, overweight and obesity. Sugar abuse is also associated with an increased risk of type 2 diabetes and cardiovascular disease.

But what about the links between sugar consumption and cancer? If this relationship is less clear, many research works are in progress to explore it, and their first results give food for thought. What do we know so far? What’s left to discover? Which sugars are affected? Could artificial sweeteners be an alternative?

Complex carbohydrates or simple sugars?

Proteins, lipids (“fats”) and carbohydrates (“sugars”) constitute the major part of our energy intake. Together with water, these three families of nutrients represent 98% of the weight of the food we eat, hence their name “macronutrients”.

The term carbohydrates covers not only complex carbohydrates, provided in particular in the form of starch by starchy foods such as potatoes, rice or pasta, but also simple sugars, more commonly referred to as “sugars”. These simple sugars are naturally present in certain foods, such as fruits, mainly in the form of fructose, and dairy products, in the form of lactose and galactose. They can also be added by the consumer, the cook or the industrialist, in the form of sucrose.

To determine the impact of a food on the level of sugar in the blood, called glycemia, two specialists in nutritional sciences, David Jenkins and Tom Wolever, developed the glycemic index in the 1980s. It reflects the ability of a food to change blood sugar within two hours of ingestion.

To read also:
Sugar and diet: what do we really know about the links between glycemic index and health?

From its glycemic index, we can calculate the glycemic load of a food. This concept, developed in the late 1990s, corresponds to the impact it will have on blood sugar levels, depending on the portion ingested. Since then, several studies have looked at the link between sugar intake or glycemic load and the risk of cancer.

Sugar, weight gain, insulin and cancer

Some hypotheses maintain that the role of simple sugars in the appearance of certain cancers would go through weight gain. Indeed, studies have established high levels of evidence between the consumption of sugary drinks, important sources of simple sugars and the increased risk of overweight and obesity, overweight and obesity being themselves known risk factors for different cancers: cancers of the oesophagus, pancreas, liver, breast after menopause, endometrium, kidney and colorectal cancer.

However, other mechanisms could also be involved, even in the absence of weight gain. Indeed, having a diet rich in simple sugars induces a significant production of insulin, the hormone that regulates blood sugar. However, insulin is an agent which is said to be “mitogenic”, that is to say that it can promote the proliferation of tumor cells.

In 2018, the latest joint report by the World Cancer Research Fund and the American Institute for Cancer Research indicated that a high glycemic load from the diet is a probable risk factor for cancer of the endometrium, the lining that lines inside the uterus where the pregnancy takes place.

Finally, studies carried out within the NutriNet-Santé cohort, on more than 100,000 people, have suggested associations between the consumption of simple sugar, that of sugary drinks and sugary products as well as the glycemic load and an increased risk of cancers, especially breast cancer. And this, regardless of weight gain.

However, further studies are needed to explore these results further. In particular, it is necessary to determine the differences between the types or sources of sugars and the risk of cancer. One can indeed wonder if the sugars of fruits, sugary drinks, dairy products all have the same effect on health.

Limit intake of simple sugars

Given these potential deleterious effects on health, public health organizations recommend limiting your intake of simple sugars. In France, the National Agency for Health, Food, Environment and Work Safety (Anses) recommends consuming less than 100 grams per day (excluding lactose and galactose, which are present in milk and dairy products).

It is also recommended to limit your consumption of sugary drinks, including sodas and fruit juices, which are as high in sugar as sodas on average, to no more than one per day.

One would think that an alternative would be to replace sugar with artificial sweeteners. But this might not be an ideal solution, as several experimental and epidemiological studies indeed suggest potential adverse effects of these food additives on health.

Artificial sweeteners, a false good solution?

Artificial sweeteners are sweeteners that are not carbohydrates. They reduce the added sugar content in foods and beverages – and the calories associated with them – while maintaining a sweet taste. Aspartame (E951) or acesulfame potassium (E950) are probably among the best known of these food additives, which are now consumed every day by millions of consumers.

Present in thousands of products manufactured by the agro-food industries, artificial sweeteners can also be added later to foods, in the form of “sweets” or powders, for example.

However, for several years, data seem to indicate that the consumption of these products could not be insignificant. Thus, recent studies carried out as part of the NutriNet-Santé study (a public health study launched in 2009 with the aim of advancing knowledge between diet and health) show an association between the consumption of sweeteners and a increased risk of cancer.

These are, overall, breast cancer, and cancers “linked to obesity”, in other words for which obesity is one of the risk factors: cancer of the pancreas, liver, colon-rectum, breast after menopause, endometrium, kidney, esophagus, mouth, larynx, pharynx, stomach, gallbladder, ovaries and prostate. An increased risk of cardiovascular disease has also been demonstrated.

Beyond these links, it should be noted that health authorities do not recommend sweeteners, which maintain the craving for sweet taste, as a safe alternative to sugar… They rather recommend the opposite, namely to tend overall towards a reduction in the sweet taste in our food. Sweet, yes, but in moderation, in short…

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