Myth Busting: Sugar, Dairy, and Soy & Cancer

There are many myths associated with diet and cancer. The top three that I am asked about most are sugar, dairy, and soy. So, in this article, we’ll discuss all three.

Sugar

Let’s start with sugar because this is a topic that frequently raises concerns across most cancer types.

There’s a common misconception that sugar from your food is going to directly cause or feed cancer. Let’s clarify this with some science.

Sugar in its simplest form is a molecule called glucose. Glucose provides energy for all cells in the body, including both healthy and cancer cells. Like healthy cells, cancer cells don't rely on glucose alone. They also need proteins and fat. It isn’t possible to starve cancer cells only, without impacting the rest of our body's cells too.

Taking out all sources of glucose from the diet is not only unsupported by robust evidence, but it can also lead to a lack of essential nutrients like fibre, vitamins, minerals and plant-based chemicals that whole foods provide.

Instead of removing sugar, focus on a balanced diet that nourishes healthy cells and supports your immune system.

It’s important to remember that glucose is found in a lot of different foods, and that not all foods are nutritionally equal.

Sugary foods like sweets, cakes, biscuits and sugary drinks are high in calories but low in nutrients and fibre. These foods can cause a rapid rise and fall in blood glucose levels, leading to energy crashes and craving more sugary foods.

Healthier sources of sugar are found in plant foods such as fruits, vegetables, beans, chickpeas, lentils, grains, nuts and seeds. There is a lot of science that tells us these types of foods are beneficial for our bodies in many ways, so we should focus on including plenty of them in our diet.

There’s no need to completely cut out all added sugars. If you want to enjoy a cake, sweet, biscuit or chocolate then that's fine and can be part of a balanced diet that includes plenty of fibre-rich plant foods.

Remember, food is for enjoyment too! By keeping a balanced approach, you can nourish your body while enjoying the foods you love.

Dairy

Dairy is another topic that dietitians commonly get asked about when it comes to diet and cancer. There’s some conflicting evidence around dairy, so it’s no wonder people feel confused about what to do.

Extensive research shows no strong evidence linking dairy to increased cancer risk. In fact, some studies suggest dairy may help protect against breast and colorectal cancers due to the calcium it contains.

There is also no strong evidence that dairy promotes cancer growth due to naturally occurring hormones.

In the UK, growth hormones are not used in cattle, and regulations ensure no antibiotics are in dairy products. So, if you enjoy dairy, it's safe to include it in your diet.

If you prefer to be dairy-free, it’s important to know that very few plant milks match the nutritional profile of cow’s milk. Wherever possible, choose a product that has:

• Added calcium

• Preferably iodine and other nutrients to replace what you'd get from dairy

Be aware that organic plant-based alternatives often lack added vitamins and minerals, which means you might be missing out.

Check the ingredients list and aim for products with little or no added sugars and minimal preservatives. Finally, shake your plant-based milk well before using it, as the vitamins and minerals can settle at the bottom of the carton.

Incorporate dairy in moderation — milk or kefir with breakfast, cheese at lunch, and yoghurt with fruit in the evening.

Enjoy dairy if you like it, and ensure your diet remains balanced.

Soy

Soy is often debated for its safety in the diet. Let's clear up the confusion with some science.

Historically, concerns arose that plant chemicals in soy could stimulate cancer cell growth, particularly in hormone-sensitive cancers. Soy contains isoflavones, which are a type of plant-based chemical known as phytoestrogens. Phytoestrogen has a similar structure to the hormone oestrogen, but they behave differently to the hormone.

When consumed, they interact with oestrogen receptors in the body, in a helpful and protective way. Recent global evidence suggests soy foods might reduce the risk of breast cancer recurrence and promote longevity.

Try incorporating soy foods such as:

• Tofu