Cancer Research UK: There’s a lot of confusing information and advice out there around sugar.
It’s been made the villain of our diet, but where does the consensus lie between how sugar and cancer are linked?
Does it cause cancer? Does sugar feed cancer cells, making them grow more aggressively? And how does the sugar we consume through food and drink affect our health, and what can be done about this?
In this post we’re taking a long hard look at sugar.
We’ll focus specifically on sugar and cancer, busting some myths and covering what researchers are studying in the hopes of finding new ways to treat people with cancer.
And we’ll cover why the amount of sugar in our diets is cause for concern. A high-sugar diet can be bad news when it comes to cancer risk, but not for the reasons that often appear in the headlines.
But first the basics, what our bodies need sugar for and where it comes from in our diet.
GLUCOSE – THE FUEL OF LIFE
Search for sugar and cancer on the internet and it doesn’t take long to find alarming warnings that sugar is the “white death” and “cancer’s favourite food”.
But this idea that sugar is responsible for kick-starting or fuelling a cancer’s growth is an over-simplification of some complicated biology. Let’s start with what sugar actually is.
Sugar comes in many different forms. The simplest form is just as a single molecule, such as glucose and fructose. These molecules of simple sugars can also stick together, either in pairs or as longer chains of molecules. All of these combinations of molecules are carbohydrates, and are our body’s main source of energy.
The form of sugar most of us will be familiar with is table sugar, which is a simple sugar that dissolves in water and gives things a sweet taste. Its proper name is sucrose, and it’s made up of crystals of glucose and fructose. Table sugar is refined, meaning it’s been processed to extract it from a natural source (usually sugar beet). Unprocessed foods can be high in simple sugars too, for example honey (also made mostly of glucose and fructose) is nearly pure sugar.
As chains of sugar get longer, they lose their sweet taste and won’t dissolve in water anymore. These chains are called polysaccharides and form a large component of starchy foods. Starchy foods such as rice, bread, pasta and vegetables like potatoes might not taste sweet, but they are high in carbohydrate too.
Sugar, in some form, is in many things we eat. And this is good, because our bodies rely heavily on it to work.
Nearly every single part of our body is made of living cells. And it’s these cells that help us see, breathe, feel, think and much more.
While their jobs in the body may differ, one thing all these cells have in common is that they need energy to survive and perform their duties.
Cells somehow need to turn nutrients in our diet into a form of energy that they can use, called ATP. It would take a long time to explain this (if you’re interested you might want to read more), but simplistically the process starts with glucose.
Glucose is the basic fuel that powers every single one of our cells. If we eat or drink things that are high in glucose, such as fizzy drinks, the glucose gets absorbed straight into our blood ready for our cells to use. If a starchy food, such as pasta, is on the menu, the enzymes in our saliva and digestive juices break it down and convert it into glucose. And if for some reason there’s no carbohydrate in our diet, cells can turn fat and protein into glucose as a last resort, because they need glucose to survive.
It’s here that sugar and cancer start to collide, because cancer is a disease of cells.
SUGAR AND CANCER
Cancer cells usually grow quickly, multiplying at a fast rate, which takes a lot of energy. This means they need lots of glucose. Cancer cells also need lots of other nutrients too, such as amino acids and fats; it’s not just sugar they crave.
Here’s where the myth that sugar fuels cancer was born: if cancer cells need lots of glucose, then cutting sugar out of our diet must help stop cancer growing, and could even stop it developing in the first place. Unfortunately, it’s not that simple. All our healthy cells need glucose too, and there’s no way of telling our bodies to let healthy cells have the glucose they need, but not give it to cancer cells.
There’s no evidence that following a “sugar-free” diet lowers the risk of getting cancer, or boosts the chances of surviving if you are diagnosed.
And following severely restricted diets with very low amounts of carbohydrate could damage health in the long term by eliminating foods that are good sources of fibre and vitamins.
This is particularly important for cancer patients, because some treatments can result in weight loss and put the body under a lot of stress. So poor nutrition from restrictive diets could also hamper recovery, or even be life-threatening.
A STICKY END FOR SUGAR RESEARCH?
Although there’s no evidence that cutting carbohydrates from our diet will help treat cancer, important research has shown that understanding the abnormal ways that cancer cells make energy could lead to new treatments.
Back in the 50s, a scientist called Otto Warburg noticed that cancer cells use a different chemical process from normal cells to turn glucose into energy.
Healthy cells use a series of chemical reactions in small cellular ‘batteries’ called mitochondria. The Warburg Effect, as it was dubbed following Otto’s discovery, describes how cancer cells bypass their ‘batteries’ to generate energy more rapidly to meet demand.
This shortcut for making energy might be a weakness for some cancers that gives researchers an advantage for developing new treatments.
Firstly, it opens up the potential for developing drugs that shut down cancer cells’ energy-making processes but don’t stop healthy cells making energy. And researchers are testing drugs that work in this way.
Secondly, the abnormal processes in cancer cells can also leave them less able to adapt when faced with a lack of other nutrients, like amino acids. These potential vulnerabilities could lead to treatments too.
But these approaches are still experimental, and we don’t know yet if treatments that starve cancer cells are safe or if they work.
It’s certainly not grounds for cancer patients to try and do it themselves by restricting their diet during treatment – and going back to our earlier point, it could be dangerous to do so.
IF SUGAR DOESN’T CAUSE CANCER, WHY WORRY ABOUT IT?
Cutting out sugar doesn’t help treat cancer, and sugar doesn’t directly cause cancer. Why then do we encourage people to cut down on sugary foods in our diet advice?
That’s because there is an indirect link between cancer risk and sugar. Eating lots of sugar over time can cause you to gain weight, and robust scientific evidence shows that being overweight or obese increases the risk of 13 different types of cancer. In fact, obesity is the single biggest preventable cause of cancer after smoking, which we’ve written about many times before.
It’s added sugar we’re mainly concerned with when it comes to weight gain, not sugar that is naturally found in foods like fruits and milk or healthy starchy foods like wholegrains and pulses (which people should be eating more of*).
HOW CAN I CUT DOWN ON ADDED SUGAR?
One of the easiest ways to lower your added sugar is to cut down on sugary drinks, which are the largest source of sugar in the UK diet.
Some sugary drinks, such as fizzy drinks and energy drinks, can have more than the recommended daily maximum amount of added sugar in one serving alone. And while these extra calories promote weight gain, they offer no other nutritional benefits.
Multiple cues push us as customers to stack junk food into our shopping baskets, even if we weren’t planning to
– Professor Linda Bauld, Cancer Research UK
Other obviously sugary foods such as sweets, chocolate, cakes and biscuits are all best kept as treats too. But some foods that have hidden high amounts of added sugar may surprise you. Some breakfast cereals, ready meals (including ‘healthy’ ones), pasta sauces and yoghurts can have shocking amounts of sugar added to them. Reading nutrition information labels and checking the ingredients list can help you choose lower sugar options.
While there are steps you and your family can take to cut down on added sugar, making these changes can be easier said than done. And it’s here that governments need to lend a hand.
“Multiple cues push us as customers to stack junk food into our shopping baskets, even if we weren’t planning to,” says Professor Linda Bauld, our cancer prevention champion based at the University of Edinburgh. “That’s why we want the Government to help create a better food environment where the healthy choice is the easy choice for everyone.”
We’re delighted that the sugar tax, which came into effect in April 2018, has already had an impact, with some of the biggest drink companies changing their recipes to reduce sugar. The tax could prevent millions of cases of obesity, and obesity-linked cancers in the future, by reducing the amount of sugar the nation consumes in fizzy drinks.
But the Government hasn’t made much progress in its plan to reduce the amount of sugar in the types of foods that are very popular with children. One year into the programme, industry has failed to meet the voluntary targets set by Government, showing that a voluntary approach just isn’t as effective.
NO SWEET ENDINGS
The story about sugar and cancer is complicated.
On the one hand, sugar itself doesn’t cause cancer, and there’s no way (at the moment) of specifically starving cancer cells of glucose without harming healthy cells too.
There’s also no evidence that adopting a diet very low in carbohydrate will lower your cancer risk or help as a treatment. And for patients, getting adequate nutrition is important for helping their bodies cope with treatment.
But we’re concerned about the amount of added sugar people are consuming because it’s promoting weight gain. And being overweight or obese increases the risk of least 13 types of cancer.
So the take home message is that although banishing sugar won’t stop cancer in its tracks, we can all reduce our risk of getting cancer by making healthy choices, and lowering the amount of added sugar in our diets is a good way to help maintain a healthy body weight.
*While foods like fruit, milk and healthy starchy foods are high in carbohydrate, they have other important nutritional benefits. We should all be eating more whole fruits, vegetables, wholegrains and pulses as these nutritious foods are also high in fibre – this not only helps your body digest the natural sugar more slowly (which helps you keep a healthy weight), it also reduces the risk of bowel cancer.
Image credit: SlideShare
POPULAR MYTHS ABOUT THE CAUSES OF CANCER
(Cancer Research UK – Science blog) Google ‘cancer’ and you’ll be faced with millions of web pages. And the number of YouTube videos you find if you look up ‘cancer cure’ is similarly vast.
The problem is that much of the information out there is at best inaccurate, or at worst dangerously misleading. There are plenty of evidence-based, easy to understand pages about cancer, but there are just as many, if not more, pages spreading myths.
And it can be hard to distinguish fact from fiction, as much of the inaccurate information looks and sounds perfectly plausible. But if you scratch the surface and look at the evidence, many continually perpetuated ‘truths’ become unstuck.
Mayo Clinic: Misconceptions about cancer causes can lead to unnecessary worry about your health. Find out whether there’s any truth to these common myths about the causes of cancer.
Scary claims circulate on the internet that everyday objects and products, such as plastic and deodorant, are secret cancer causes. Beyond being wrong, many of these myths may cause you to worry unnecessarily about your own health and the health of your family.
Before you panic, take a look at the facts.
Here, Timothy J. Moynihan, M.D., a cancer specialist at Mayo Clinic, Rochester, Minnesota, takes a closer look at some popular myths about cancer causes and explains why they just aren’t true.
MYTH: PEOPLE WITH CANCER SHOULDN’T EAT SUGAR, SINCE IT CAN CAUSE CANCER TO GROW FASTER
Fact: Sugar doesn’t make cancer grow faster. All cells, including cancer cells, depend on blood sugar (glucose) for energy. But giving more sugar to cancer cells doesn’t speed their growth. Likewise, depriving cancer cells of sugar doesn’t slow their growth.
This misconception may be based in part on a misunderstanding of positron emission tomography (PET) scans, which use a small amount of radioactive tracer — typically a form of glucose. All tissues in your body absorb some of this tracer, but tissues that are using more energy — including cancer cells — absorb greater amounts. For this reason, some people have concluded that cancer cells grow faster on sugar. But this isn’t true.
However, there is some evidence that consuming large amounts of sugar is associated with an increased risk of certain cancers, including esophageal cancer. It can also lead to weight gain and increase the risk of obesity and diabetes, which may increase the risk of cancer.
MYTH: ANTIPERSPIRANT OR DEODORANTS CAN CAUSE BREAST CANCER
Fact: There’s no conclusive evidence linking the use of underarm antiperspirants or deodorants with breast cancer, according to the National Cancer Institute and other research.
Some reports have suggested that these products contain harmful substances such as aluminum compounds and parabens that can be absorbed through the skin or enter the body through nicks caused by shaving. No clinical studies have yet given a definitive answer to the question of whether these products cause breast cancer. But the evidence to date suggests these products don’t cause cancer.
If you’re still concerned that your underarm antiperspirant or deodorant could increase your risk of cancer, choose products that don’t contain chemicals that worry you.
MYTH: MICROWAVING PLASTIC CONTAINERS AND WRAPS RELEASES HARMFUL, CANCER-CAUSING SUBSTANCES INTO FOOD
Fact: Microwave-safe plastic containers and wraps are safe to use in the microwave.
But plastic containers not intended for use in the microwave could melt and potentially leak chemicals into your food. So avoid microwaving containers that were never intended for the microwave, such as margarine tubs, takeout containers or whipped topping bowls.
Check to see that any container you use in the microwave is labeled as microwave-safe.
MYTH GOOD PEOPLE DON’T GET CANCER
Fact: In ancient times, illness was often viewed as punishment for bad actions or thoughts. In some cultures that view is still held.
If this were true, though, how would you explain the 6-month-old or the newborn who gets cancer? These little ones haven’t been bad.
There’s absolutely no evidence that you get cancer because you deserve it.
MYTH: CANCER IS CONTAGIOUS
Fact: There’s no need to avoid someone who has cancer. You can’t catch it. It’s OK to touch and spend time with someone who has cancer. In fact, your support may never be more valuable.
Though cancer itself isn’t contagious, sometimes viruses, which are contagious, can lead to the development of cancer. Examples of viruses that can cause cancer include:
- Human papillomavirus (HPV) — a sexually transmitted infection — that can cause cervical cancer and other forms of cancer
- Hepatitis B or C — viruses transmitted through sexual intercourse or use of infected IV needles — that can cause liver cancer
Cancer.Net: MYTH: IF YOU HAVE A FAMILY HISTORY OF CANCER. YOU WILL GET IT TOO
FACT: Although having a family history of cancer increases your risk of developing the disease, it is not a complete prediction of your future health. An estimated 4 out of 10 cancers can be prevented by making simple lifestyle changes, such as forming healthy eating habits, maintaining a healthy weight, exercising, limiting alcoholic beverages, and avoiding tobacco products. Additionally, if you have inherited certain cancer genes that put you at high risk for cancer, your doctor may recommend surgery or medications to reduce the chance that cancer will develop.
MYTH: CANCER TREATMENT IS USUALLY WORSE THAN THE DISEASE
FACT: Although cancer treatments, such as chemotherapy and radiation therapy, can cause unpleasant and sometimes serious side effects, recent advances have resulted in many drugs and radiation treatments that are much better tolerated than in the past. As a result, symptoms like severe nausea and vomiting, hair loss, and tissue damage are much less common. However, managing side effects, also called palliative care, remains an important part of cancer care. Palliative care can help a person feel more comfortable at any stage of illness. In fact, people who receive both treatment for the cancer and treatment to ease side effects at the same time often have less severe symptoms, better quality of life, and report they are more satisfied with treatment.
Mayo Clinic: Dr. Timothy Moynihan, an emeritus Mayo Clinic oncologist, explains the facts surrounding five widespread myths about the causes of cancer.
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Chronic lymphocytic leukemia is a type of cancer of the blood and bone marrow that most commonly affects older adults. Complications include frequent infections, increased risk of other cancers and immune system problems. People with early stage chronic lymphocytic leukemia typically don’t receive treatment. Treatment for the intermediate and advanced stages may include chemotherapy, targeted drug therapy, immunotherapy and bone marrow transplant. Learn more about these treatment options and what your health care provider may recommend for you.
Talk to your doctor about ways to protect yourself from these viruses.
What are your thoughts?