Are fizzy drinks bad for you?
Whether it’s worries about sugar levels or health concerns over sweeteners, or even being blamed for the nation’s obesity issues, fizzy drinks are always in the news. But are they really so unhealthy? Nutritionist Kerry Torrens explores.
With a market share of 38.3% (2021) fizzy or carbonated drinks (also known as soda) make up the biggest category of soft drinks in the UK. Ranging from plain carbonated water to cola, lemonade, fruit drinks, ginger ales and mixers such as tonic water, it’s the carbon dioxide in these drinks that makes them fizzy. In addition to the bubbles, your glass is likely to contain sugar, artificial sweeteners such as aspartame, Acesulfame K, sucralose and saccharin, along with flavourings, preservatives and colours.
In 2018 the UK introduced the Soft Drink Industry Levy (‘sugar tax’), which prompted a number of manufacturers to reformulate their products to lower sugar levels – in practical terms this means artificial sweeteners may now be found in both diet and non-diet versions of fizzy drinks. Caffeine is a common ingredient especially in cola, with typical preservatives being phosphoric and citric acid.
Although you’d be forgiven for thinking these popular drinks were a recent invention, they’ve been around since the late 18th century when Dr Joseph Priestley discovered a way of artificially carbonating water. Of course, they’ve evolved a lot since then and are now designed to hit the ‘sweet’ spot, being engineered so the bubbles deliver just the right amount of acidity that, when combined with sugar, you receive a euphoric feel-good feeling. It all makes a chilled can hard to resist.
Are fizzy drinks bad for our health?
Regularly drinking sugary fizzy drinks has been linked to various health problems from tooth decay and weight gain to an increased risk of chronic diseases including heart disease and type 2 diabetes. The reason for this is that these drinks often have high levels of sugar and calories, contribute no vitamins or minerals, and are very acidic.
Read on to discover how fizzy drinks impact:
More like this
· blood sugar levels
· liver function
· type 2 diabetes
· appetite
· weight gain and obesity
· dental health
· heart disease
· bone health
· reproductive hormones
· cancer
Read more about how much sugar we should have in a day and how much sugar children should have.
10 reasons to drink fewer fizzy drinks
1. They disrupt blood sugar levels
Fizzy drinks are acidic, which causes the sugar they contain to break down into its component parts – glucose and fructose. This readily available glucose is absorbed quickly by the body and the sudden surge in levels triggers the pancreas to release the hormone insulin to manage supply. The burst of ready energy is short lived and typically followed by a rapid drop, triggering a roller coaster effect that influences our appetite, behaviour and ability to concentrate.
2. They make the liver work harder
The fructose in a can of pop is metabolised by the liver, meaning high levels in the diet put an extra burden on this key organ. Excessive fructose is known to be a key driver in non-alcoholic fatty liver disease as this sugar is often converted to fat by the liver.
3. Could lead to type 2 diabetes
Regular disruption of blood sugar levels due to too much sugar means our cells become less sensitive to the effects of insulin and, as a result, the pancreas needs to make even more to be effective. In conjunction with this, too much fructose promotes insulin resistance in the liver. No surprise then that studies suggest drinking as little as one can of fizzy drink per day has consistently been linked to an increased risk of type 2 diabetes.
4. They disrupt appetite
Sweetness in the form of fructose doesn’t lower the hungry hormone, ghrelin, in the same way as glucose. This means that when we drink fizzy drinks, despite the calories we are consuming, we don’t receive the same fullness message, leaving us prone to consume more.
5. They cause weight gain
Studies show people who drink sugary drinks consistently gain more weight than those who don’t and – contrary to popular belief – ‘diet’ drinks also show a correlation with weight gain.
6. They cause tooth decay
Fizzy, sugary drinks are the largest single source of sugar for children aged 11-18 years, providing an average of 29% of their daily sugar intake. This high sugar consumption leads to tooth decay, with the acid in the drink also weakening tooth enamel. While drinking ‘diet’ versions of fizzy drinks cuts the sugar, they are still highly acidic and remain a cause of enamel erosion.
Read more about caring for your child’s teeth.
7. They may increase heart disease risk
There has long been an association between sugar intake and heart disease, with sugary drinks increasing risk factors such as blood sugar and blood triglycerides including LDL cholesterol (the type typically referred to as ‘bad’ cholesterol).
8. They may weaken bones
Phosphoric acid (used as a preservative in many fizzy drinks) is thought to have an impact on bone density, perhaps because it reduces the amount of calcium the body can absorb. Some studies suggest more than just two of these drinks a day increases the risk of hip fracture in post-menopausal women.
9. May influence reproductive hormones
A study from 2015 reported that girls who drank more than 1½ servings of sugar-sweetened drinks, including fizzy drinks per day, experienced an estimated 2-7 month earlier first menstrual cycle than those who did not. In older adults, the consumption of sugary fizzy drinks has been associated with reduced fertility for both men and women.
10. May increase the risk of cancer
A number of observational studies suggest a strong association between sugary drink consumption and cancer. One study reported that for each additional 100ml per day there was an 18% relative risk increase of any cancer, with also a significant association with breast cancer for both pre- and post-menopausal women.
What is the recommended limit of fizzy drinks per day?
Although there is no set limit for the number of fizzy drinks that are acceptable each day, there are recommended limits for the amount of ‘free sugar’ we consume. The UK government recommends ‘free sugars’ make up no more than 5% of our daily calories. This equates to no more than 30g of ‘free sugars’ per day for adults and children over 11 years and 24g for children aged between seven and 10 years. In practical terms, if you are an adult or older child this limit is less than one can (330ml) of regular cola, which contains 35g of ‘free sugar’ or nearly nine teaspoons.
If you do choose to drink fizzy drinks, enjoy them as an occasional treat rather than every day, and if plain water is simply too boring, try one of these refreshing alternatives:
- Dilute a small amount of 100% unsweetened fruit juice with sparkling water
- Make up a pot of herbal fruit tea, allow to cool and chill in the fridge, enjoy chilled on its own or combine with sparkling water
- Add slices of lemon or lime to sparkling water
- Make your own fruit-infused water
- A chilled glass of mildly fizzy kombucha makes a refreshing grown-up alternative, but be aware that commercial varieties may contain added sugar, including fructose
For more ways to cut your sugar intake check out our article 8 ways to cut down on sugar.
The bottom line…
While sugary fizzy drinks may be consumed in moderation as part of a varied and balanced diet, excessive consumption may have detrimental effects on your health. This is because:
- Fizzy drinks have high levels of sugar and calories, and contribute no nutritional value
- Consuming them regularly may lead to poor dental health, blood sugar swings, weight gain, hormonal disruption and appetite disturbance
- UK guidelines recommend adults and children over 11 years limit their sugar intake to 30g of sugar per day (7½ teaspoons) – you can easily blow this by drinking just one 330ml can of cola
If you do prefer carbonated drinks and they make up a substantial part of your daily hydration, stick to carbonated water. Studies suggest it damages tooth enamel substantially less than a glass of sugary soda. That said, to minimise damage further, enjoy it at meal times when the chewed food and increased saliva flow helps neutralise the acidity in the mouth.
Enjoyed this? Now read:
How much sugar is in a can of cola?
Sweet tooth? 10 ways to manage your sugar cravings
How much sugar is in your snack?
Kerry Torrens is a qualified Nutritionist (MBANT) with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Applied Nutrition and Nutritional Therapy (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food.
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