Sugar and Cancer: sweet indulgence, or sinister consequences?

There’s a lot of conflicting information when it comes to sugar and its involvement in the cancer process. Common questions we hear include: Does sugar feed cancer cells? Are we talking refined sugars or all carbohydrates? Do sweeteners cause cancer? What are safe alternatives? The list goes on... Information on the internet is increasingly confusing, making it difficult for anyone trying to get reliable information about how sugar may affect their personal situation.

We are here to help.

The links between sugar and chronic disease are plastered all over the internet and Netflix documentaries. Sugar is painted as the bad guy, resulting in fear and radical diets to quit all carbohydrates. Certainly, refined sugars are undoubtedly detrimental to health, however, the idea that sugar is the only culprit behind fuelling a cancer’s growth is an easy scapegoat for a much more complicated cellular process.

This blog will aim to answer the above questions to help form an understanding around sugar and its effect on cancer- but before we do that, we’ll need to lay down some foundations.

What is sugar?

Sugar comes in many different forms; the most common and simplest form of sugar is known as glucose. This simple sugar can be bound together in pairs or longer chains of glucose in various combinations, making up one of our major macronutrients called carbohydrates. In short, carbohydrates are our body’s main and most effective source of energy.

Common carbohydrate-rich foods we have in our diet include starchy vegetables, fruit, legumes and grains. These are complex carbohydrates, and they all contribute largely to our intake of fibre, proteins, vitamins and minerals. Processed foods are also rich in carbohydrates but the simple kind, usually via the addition of refined flours and refined sweeteners. They may have many names on an ingredient label: sugar, glucose, sucrose, lactose, dextrose, fructose, high fructose corn syrup, corn syrup solids, maltodextrin, maple syrup, brown rice syrup, honey, blackstrap molasses, agave nectar, evaporated cane juice, fruit juice concentrate, invert sugar… the list goes on.

Now when we talk about “sugar” we do need to distinguish between the complex carbs (in whole food, as they are found in nature, and combined with many other nutrients) versus simple carbohydrates which rapidly increase blood sugar levels and provide no nutritional value other than a spike in energy.

Source: < https://www.tasteofhome.com/article/how-is-sugar-made/>

Is there a link between sugar and cancer?

Cancer essentially is a situation of rapid and excessive growth of dodgy cells. These fast growing and multiplying cells require a lot of energy compared to normal cells, and many cancer types (but not all) do have a preference for glucose as their main fuel source. This phenomenon was identified almost a century ago and termed “the Warburg Effect”: the characteristic that cancer cells rewire their metabolism to increase glucose uptake and efficiently ferment it to produce lactate. Research into the detailed metabolism of cancer cells has really been ramping up in the last decade, leading to the interpretation that drastic dietary restriction such as a Ketogenic Diet, should be an effective strategy to “starve cancer”.  

It does make logical sense: If a cancer cell needs glucose to multiply, then cutting out sugar must stop cancer cell growth or even cause cell death. However, this is being debunked clinically, as we see individuals going keto or sugar-free but this not resulting in the desired reduction in cancer progression. Not to mention, the body will always have a level of glucose in the blood stream, due to an essential process called homeostasis (or balance). If there isn’t enough glucose in the body, it will simply make some (for example, via glycogenolysis and gluconeogenesis).

PS – to see our blog posts on a Ketogenic Diets in Cancer Care here, and a blog on Mediterranean versus Keto in Breast Cancer here .

What IS becoming evident is that not all cancer cells are alike and most of them also use other nutrients as fuel sources, such as amino acids (proteins) and fats. The reality is that the other, healthy cells in body need glucose too, and the carbohydrate food sources contain other valuable macro- and micronutrients we need for optimal physiological function. When we cut out any major food group, this puts the body at risk of becoming deficient in key nutrients that help the immune system fight against cancer cells. In short, dietary change should be personalised to the individual, their health and their situation, not based on fear and misinformation.

Let’s break down some more of the above questions down below.

Does sugar intake cause cancer?

Although there is no evidence that explicitly shows a sugar-free diet lowers the risk of cancer, there is evidence that shows a Western-style diet, rich in refined carbohydrates, processed foods and saturated fats, indeed increases cancer risk (and various other health issues, for that matter). Furthermore, the weight-gain caused by a diet high in sugar can also contribute to cancer risk and progression. Excess abdominal fat (aka central adiposity) in particular is more strongly linked to Colorectal Cancer risk than overall obesity, and contributes to Breast Cancer risk, mortality and risk of recurrence, amongst others.

Source: Unsplash

Now, what does this have to do with sugar? When we consume large amounts of sugar that is not used for energy, the body will store this sugar as fat to be used at a later stage. However, if we don’t ever use that stored fat and allow it to keep building, the fat begins to become more and more biologically active, and it can cause changes in the body’s biochemistry. These changes include things like ineffective blood sugar control, chronic inflammation and dysregulated hormone function (yep ladies and gentlemen, we store excess oestrogen and cortisol in our fat).

It's these changes that chronically alter the biochemistry of the body that begin to create the microenvironment for the first cancer cells to start growing, multiplying and spreading. Let’s break down some of these biochemical changes some more and understand how and why they may contribute to cancer growth.

Blood Sugar Control

Efficient blood sugar control is vital for our survival. Insulin is like the bodyguard that allows glucose to enter our cells to be used for energy and signal the body to grow and store resources for later. Insulin in turn activates a range of other biochemical cascades, including the elevation of  insulin-like growth factors (IGF) and other growth hormones (GH). Under normal conditions, IGF and GH are mainly seen in high levels during childhood and puberty (ie life stages of growth) during which they work together to ensure normal energy production for development. Later in life, IGF and GH elevation are seen with lifestyle factors like poor dietary choices, central adiposity and metabolic syndrome, chronic stress, and hormonal dysregulation. Particularly elevated IGF levels are known to be involved in growth, proliferation and cancer risk.

Stress

When we are highly stressed our body produces a hormone called cortisol. In small doses, cortisol activates our fight or flight response, helps us fight infection, lowers sensitivity to pain and has some anti-inflammatory benefits in the short-term. When cortisol release becomes chronic, a shift in these protective effects begins to happen, causing adaptive changes in the body including slowed metabolism, nervous system impacts and chronic inflammation. In fact, long-term cortisol release can increase blood sugar levels - a mechanism which may increase an individual’s risk for type-2 diabetes. This process can contribute to further inflammation and oxidative stress in the body that can cause damage to the DNA of healthy cells. The changes in DNA of healthy cells begins the process of cancer cell growth.

Inflammation

We often think of inflammation as being a negative process, but it is actually a normal and necessary part of a healthy immune system. In the short-term, inflammation increases blood flow to an area, to send messengers which help us fight off infections, repair wounds and more. The problem with inflammation is when it becomes long-term, or chronic. There are several things that can cause inflammation like tissue injury, exposure to toxins, bacteria, viruses, foods, long-term stress and environmental pollutants, and long-term exposure to some of these factors may contribute to a chronic inflammatory response. Alternatively, there may also be a lack of certain control mechanisms in charge of regulating the inflammatory response. Thus, when we have this chronic inflammatory picture cell mutations and proliferation can result, often contributing to the microenvironment that is associated with the development of cancer. In the context of sugar, it’s important to know that one incidence of sugar intake is not going to cause an inflammatory response, however, excessive or frequent intake of refined sugars will cause metabolic changes that contribute to inflammation. It’s the intake of excessive sugars that we want to avoid to try and minimise the effects of long-term inflammation.

Hormone Function

Hormones are the body’s chemical messengers, and they influence metabolism and body composition, immune function, the puberty and the menstrual cycle, and overall reproductive health. Many factors can cause fluctuating hormone levels, including lifestyle and environmental factors, such as high levels of stress, poor sleep, lack of exercise, and an unhealthy diet full of saturated fat and sugars.

Aside from weight gain, a high intake of refined carbohydrates is associated with insulin resistance, which in turn has an effect on reproductive hormones and is associated with polycystic ovarian syndrome in women, and excess oestrogen in men and women. And it turns into a vicious cycle – excess fatty tissue is very active, further producing hormones like oestrogen, storing cortisol, and producing inflammatory chemicals such as interleukins, resulting in changes to the body’s metabolism, immune function and neuro-endocrine function.

These changes in the body’s chemistry can slowly contribute to the growth of cancer cells by influencing different receptors on cells that cause oxidative stress, facilitate abnormal growth, increase blood supply to the tissues, influence immune responsiveness and cell signalling. Experimental evidence has demonstrated cross-talk between IGF, oestrogen and their respective receptors. Recent studies are elucidating a possible synergistic effect of oestrogen receptor activation and increased IGF signalling as contributing factors to breast tumour development.

Now, it’s important to note that small amounts of weight-gain aren’t necessarily indicative of cancer growth, however when combined with other chronic factors like poor blood sugar control, stress and hormonal dysregulation it can begin to start the process of carcinogenesis.

The gist is: sugar intake affects many systems and chemical pathways in the body. Infrequent indulgence is not going to be a significant problem, but what we do MOST of the time does have a significant impact on many facets of health. It is the complex interplay of many factors, particularly chronic imbalances, that impact chronic disease, including cancer development and growth.

Does sugar feed cancer cells? Does cancer get worse from sugar?

The short answer to this question is yes. Glucose feeds all our cells via a process known as oxidative phosphorylation. Many cancer cells, as mentioned above, use a different process called aerobic glycolysis (ie the Warburg Effect). However this is only one part of the complex metabolism of cancer cells that is becoming evident. Cancer cells also require other nutrients like fats (for example phospholipids and cholesterol) and proteins (for example various individual amino acids) to grow and multiply. This suggests that eliminating one macronutrient category simply doesn't make sense, and we need to use other strategies to affect metabolism at a cellular level.

When it comes to sugar, it is important to differentiate the between the different types of sugar. All carbohydrates are broken down into glucose – the question is, how quickly and how much glucose is produced.  Refined sugars like those found in processed foods, contain a lot of glucose that is very easily absorbed into the blood stream – causing a rapid rise in blood sugar levels, followed by a spike in insulin and other growth factors mentioned above, contributing to weight gain and upregulated growth hormones and inflammation. And certainly having plenty of glucose in the blood stream provides easy access to more fuel for cancer cells.

Contrastingly, if we look at complex carbohydrates like the those found in whole food sources like fruits and vegetables, this has less of an impact on contributing to cancer cell growth because blood sugar levels rise slowly and steadily. Furthermore, you are also receiving an intake of essential vitamins, minerals, antioxidants and fibre that help the body function well to essentially help fight off cancer and help you tolerate treatment better. So we say this again - there are a multitude of complex mechanisms at play like inflammation, hormones, lifestyle, stress and overall caloric intake. Sugar is one piece of the pie and only holds significance when poor quality carbohydrates are consumed in large amounts.

Source: < https://www.ruled.me/ketogenic-diet-cancer-interpreting-research/>

What about artificial sweeteners and natural non-sugar alternatives? Do sweeteners cause cancer?

Sweeteners are often advertised as non-sugar alternatives and are found in products like processed foods, “diet” yoghurts, soft drinks, ice creams and other desserts. Sweeteners can create confusion as these products are marketed as ‘healthier’ and ‘no sugar’, but are still combined with ingredients like artificial colours, flavours and preservatives that may be contributing to an imbalance in the body. When we look at sweeteners it’s important to note that there are artificial and natural sweeteners. The 2 sweeteners up for discussion are aspartame and stevia, which are the most commonly used sweeteners currently in commercial products.

The biggest trouble makers are artificial sweeteners, also known as non-nutritive sweeteners, such as Aspartame (aka 950), and many others that are used in commercial food production in Australia (eg 951, 952, 954, 955 etc). These are chemical additives that are sweeter than sugar but contain no caloric value and don’t impact blood sugar levels – which is why they are very popular in food products for Diabetics.

Aspartame was synthesized in 1965 by James Schlatter, who discovered the sweetness of the compound by accident. After initial obstacles in legalisation of the sweetener, large scale production of aspartame began in 1981. Aspartame was widely added to zero-sugar soft drinks, ice creams, cereals, gums, and often sold under the brand names of Splenda and Equal. The draw to aspartame as a sweetener was that its sweetness is approximately 200 times sweeter than sugar, while its caloric value is almost zero. A perfect marketing strategy for the increasing obesity epidemic of the 1980s.

Although the risk of negative outcomes with artificial sweeteners is minimal when consumed in very small doses, research is suggesting that average individual consumption is far exceeding recommended daily intake and was found to be highest in children aged 6-10 years. Amongst other nasty side effects, a large-scale population-based cohort study found that individuals consuming above the median intake of sweeteners, mainly aspartame and acesulfame-k, were associated with an increased cancer risk, mainly breast and obesity-related cancers. These results are clinically relevant when determining the level of artificial sweetener intake and assessing overall dietary contribution to cancer risk. The other sneaky fact about artificial sweeteners is that they actually increase risk of obesity and metabolic syndrome. By altering the hosts microbiome composition, they decrease the feeling of satiety and disrupt blood sugar control, leading to increased calorie consumption and weight gain. Yup – people that drink diet soft drinks are at even higher risk of weight gain compared to those drinking soft drinks with real sugar.

Source: < https://riverview.org/blog/uncategorized/artificial-sweeteners-are-they-safe/>

Luckily, Stevia is becoming a popular alternative to Aspartame that is much more natural. Stevia is a plant that was originally cultivated in Paraguay and Brazil, then later manufactured in Japan in the 1970’s. Today there are over 80 different species of stevia, but the one that is commonly used as a sweetener is known as Stevia Rebaudiana Bertoni, mainly for its ability to act like sugar in onset, intensity, and duration of sweetness. This species of stevia contains a compound called rebaudioside A, which is the sweet component of the plant that tastes 100 to 300 times sweeter than table sugar. Stevia was then later approved by the FDA in 1995 and began its expansion in global commercial products like Coca-Cola, Pepsi and Stoneyfield Yoghurt. When the evidence around stevia is examined, it has a good safety profile. Firstly, on a historical note, the plant has been used for over 1500 years in South America with no reports on adverse side effects. Secondly, confirmation of safety is also recognised in Japan where considerable amounts of stevia are used and consumed in large quantities. In addition to this, most of the studies that have investigated stevia have demonstrated no side effects with its consumption when used in appropriate amounts. The safety of stevia has been confirmed for up to 4mg/kg of body weight, which would equate to about 300mg for a weight of 75kg. This is a lot  of stevia, way more than one person would consume in a day. From a blood sugar perspective, stevia has no effect on blood sugar or insulin levels – woohoo.

Needless to say, this isn’t a green light to start consuming all things stevia. As health practitioners we promote everything in moderation along with a balanced lifestyle and diet. What we do want from this information is piece of mind that stevia is a safe and sweet alternative to sugar when consumed appropriately.

Image URL: < https://www.healthline.com/nutrition/is-stevia-safe>

Are there any natural ways to reduce the risk factors of some cancers?

When we look at reducing risk factors of cancers, there are several modifiable factors one can take into consideration. There are factors like lifestyle, level of physical activity, diet, rest and recovery, immune function, and hormonal health that can all be taken into consideration when looking at an individual holistically. There is also evidence to support the use of targeted products and therapies that may be used to create a shift in the body’s chemistry to help reduce the risk of cancer like herbs, nutritional supplements, acupuncture, massage and stress reduction therapies (*please always talk to a qualified practitioner before commencing any new supplement or therapy).

The main outcome we want to ensure is that these modifiable factors and use of external products or therapies are individually tailored to patients. For example, what would be recommended for someone with a higher risk of breast cancer would be different for what would be recommended for someone who recently had a prostate cancer diagnosis. It’s the individual presentation and biochemistry that gives MIOG practitioners the appropriate lens to tailor holistic treatment for patients.

Certainly, diet matters. A diet that is low in processed foods, refined carbohydrates and sugars, but rich in colourful vegetables, fruit, legumes, nuts and seeds, and lean good-quality sources of protein is most protective. A Mediterranean style diet time and time again comes out on top when we compare to other dietary patterns such as a Standard Western Diet.

Aside from reducing sugar intake, there are other things you can do to support the balancing of blood sugar levels, improve insulin sensitivity, and reduce metabolic syndrome: and that is (drum roll please) exercise.

When looking at reducing cancer risk in the scientific literature, exercise is the one modifiable factor that supports the highest reduction in cancer risk. Interestingly, in a systematic review that analysed 45 reports comprising of epidemiological studies that examined the relationship between highest versus lowest physical activity levels of cancer patients found a reduced risk of bladder, breast, colon, endometrial, oesophageal, renal, and gastric cancers. Further to this, the report also found moderate associations between greater amounts of exercise and physical activity decreased all-cause and cancer-specific mortality in individuals with breast, colon and prostate cancer with a relative risk reduction of up to 40% to 50% (that’s huge!!). This is very important clinically as this one of the best modifiable factors individuals can apply to their daily lives to reduce the risk of cancer – it is the lifestyle adjustment we MOST recommend. And no need to sweat profusely – a balanced but consistent approach between low intensity cardiovascular and weight-bearing exercise, with movement happening most days, is sufficient.

Image URL: < https://globalsportmatters.com/health/2018/10/30/over-1-in-4-people-across-the-world-dont-get-enough-exercise-study-says/>

Of course, to ensure you’re covering all bases, it’s important to look at other lifestyle factors like stress management, sleep, immune function, levels of inflammation, microbiome health and in some complex cases, genetics. Functional testing may be appropriate for some patients to add success to treatment by analysing individual biochemistry and tailoring the treatment around those results. At MIOG, we offer a variety of different functional testing to assess factors that may contribute to cancer growth like inflammatory markers, hormone metabolism, GIT mapping and cancer markers. These tests help practitioners paint a better picture of what the biochemistry is doing so that we can treat accordingly.

Conclusion

“Sugar” is a broad term that is not the be-all-end-all when it comes to cancer risk and growth. Certainly, refined sugars affect many systems and chemical pathways in the body, spiking blood sugar levels to promote weight gain, hormonal imbalance, and providing an easy instant fuel source for cancer cells. However complex carbohydrates found in natural whole foods contain valuable nutrients and fibre, important for general wellbeing as part of a balanced diet. Aside from dietary guidance, people should be supported with lifestyle education and other helpful therapies to achieve balance and wellbeing in all facets of their lives, both for preventative care and the management of chronic disease.