Still or sparkling? It’s a question you’ll commonly hear in a café or restaurant and you probably have a preference. But is there any difference for your health?

If you love the fizz, here’s why you don’t have to pass on the sparkling water.

What makes my water sparkle?

This article specifically focuses on comparing still filtered water to carbonated filtered water (called “sparkling water” or “unflavoured seltzer”). Soda water, mineral water, tonic water and flavoured water are similar, but not the same product.

The bubbles in sparkling water are created by adding carbon dioxide to filtered water. It reacts to produce carbonic acid, which makes sparkling water more acidic (a pH of about 3.5) than still (closer to neutral, with a pH around 6.5-8.5).

Which drink is healthiest?

Water is the best way to hydrate our bodies. Research shows when it comes to hydration, still and sparkling water are equally effective.

Some people believe water is healthier when it comes from a sealed bottle. But in Australia, tap water is monitored very carefully. Unlike bottled water, it also has the added benefit of fluoride, which can help protect young children against tooth decay and cavities.

Sparkling or still water is always better than artificially sweetened flavoured drinks or juices.

Isn’t soda water bad for my teeth and bones?

There’s no evidence sparkling water damages your bones. While drinking a lot of soft drinks is linked to increased fractures, this is largely due to their association with higher rates of obesity.

Sparkling water is more acidic than still water, and acidity can soften the teeth’s enamel. Usually this is not something to be too worried about, unless it is mixed with sugar or citrus, which has much higher levels of acidity and can harm teeth.

However, if you grind your teeth often, the softening could enhance the damage it causes. If you’re undertaking a home whitening process, sparkling water might discolour your teeth.

In most other cases, it would take a lot of sparkling water to pass by the teeth, for a long period of time, to cause any noticeable damage.

How does drinking water affect digestion?

There is a misconception drinking water (of any kind) with a meal is bad for digestion.

While theoretically water could dilute stomach acid (which breaks down food), the practice of drinking it doesn’t appear to have any negative effect. Your digestive system simply adapts to the consistency of the meal.

Some people do find that carbonated beverages cause some stomach upset. This is due to the build-up of gases, which can cause bloating, cramping and discomfort. For people with an overactive bladder, the acidity might also aggravate the urinary system.

Interestingly, the fizzy “buzz” you feel in your mouth from sparkling water fades the more you drink it.

Is cold water harder to digest?

You’ve chosen still or sparkling water. What about its temperature?

There are surprisingly few studies about the effect of drinking cold water compared to room temperature. There is some evidence colder water (at two degrees Celsius) might inhibit gastric contractions and slow down digestion. Ice water may constrict blood vessels and cause cramping.

However other research suggests drinking cold water might temporarily boost metabolism, as the body needs to expend energy to warm it up to body temperature. This effect is minimal and unlikely to lead to significant weight loss.

Which water wins?

The bottom line is water is essential, hydrates us and has countless other health benefits. Water, with carbonated bubbles or without, will always be the healthiest drink to choose.

And if you’re concerned about any impact to teeth enamel, one trick is to follow sparkling water with a glass of still. This helps rinse the teeth and return your mouth’s acidity back to normal.

Christian Moro, Associate Professor of Science & Medicine, Bond University and Charlotte Phelps, Senior Teaching Fellow, Medical Program, Bond University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The anterior cruciate ligament (ACL) is an important ligament in the knee. It runs from the thigh bone (femur) to the shin bone (tibia) and helps stabilise the knee joint.

Injuries to the ACL, often called a “tear” or a “rupture”, are common in sport. While a ruptured ACL has just sidelined another Matildas star, people who play sport recreationally are also at risk of this injury.

For decades, surgical repair of an ACL injury, called a reconstruction, has been the primary treatment in Australia. In fact, Australia has among the highest rates of ACL surgery in the world. Reports indicate 90% of people who rupture their ACL go under the knife.

Although surgery is common – around one million are performed worldwide each year – and seems to be the default treatment for ACL injuries in Australia, it may not be required for everyone.

What does the research say?

We know ACL ruptures can be treated using reconstructive surgery, but research continues to suggest they can also be treated with rehabilitation alone for many people.

Almost 15 years ago a randomised clinical trial published in the New England Journal of Medicine compared early surgery to rehabilitation with the option of delayed surgery in young active adults with an ACL injury. Over half of people in the rehabilitation group did not end up having surgery. After five years, knee function did not differ between treatment groups.

The findings of this initial trial have been supported by more research since. A review of three trials published in 2022 found delaying surgery and trialling rehabilitation leads to similar outcomes to early surgery.

A 2023 study followed up patients who received rehabilitation without surgery. It showed one in three had evidence of ACL healing on an MRI after two years. There was also evidence of improved knee-related quality of life in those with signs of ACL healing compared to those whose ACL did not show signs of healing.

Regardless of treatment choice the rehabilitation process following ACL rupture is lengthy. It usually involves a minimum of nine months of progressive rehabilitation performed a few days per week. The length of time for rehabilitation may be slightly shorter in those not undergoing surgery, but more research is needed in this area.

Rehabilitation starts with a physiotherapist overseeing simple exercises right through to resistance exercises and dynamic movements such as jumping, hopping and agility drills.

A person can start rehabilitation with the option of having surgery later if the knee remains unstable. A common sign of instability is the knee giving way when changing direction while running or playing sports.

To rehab and wait, or to go straight under the knife?

There are a number of reasons patients and clinicians may opt for early surgical reconstruction.

For elite athletes, a key consideration is returning to sport as soon as possible. As surgery is a well established method, athletes (such as Matilda Sam Kerr) often opt for early surgical reconstruction as this gives them a more predictable timeline for recovery.

At the same time, there are risks to consider when rushing back to sport after ACL reconstruction. Re-injury of the ACL is very common. For every month return to sport is delayed until nine months after ACL reconstruction, the rate of knee re-injury is reduced by 51%.

Historically, another reason for having early surgical reconstruction was to reduce the risk of future knee osteoarthritis, which increases following an ACL injury. But a review showed ACL reconstruction doesn’t reduce the risk of knee osteoarthritis in the long term compared with non-surgical treatment.

That said, there’s a need for more high-quality, long-term studies to give us a better understanding of how knee osteoarthritis risk is influenced by different treatments.

Rehab may not be the only non-surgical option

Last year, a study looking at 80 people fitted with a specialised knee brace for 12 weeks found 90% had evidence of ACL healing on their follow-up MRI.

People with more ACL healing on the three-month MRI reported better outcomes at 12 months, including higher rates of returning to their pre-injury level of sport and better knee function. Although promising, we now need comparative research to evaluate whether this method can achieve similar results to surgery.

What to do if you rupture your ACL

First, it’s important to seek a comprehensive medical assessment from either a sports physiotherapist, sports physician or orthopaedic surgeon. ACL injuries can also have associated injuries to surrounding ligaments and cartilage which may influence treatment decisions.

In terms of treatment, discuss with your clinician the pros and cons of management options and whether surgery is necessary. Often, patients don’t know not having surgery is an option.

Surgery appears to be necessary for some people to achieve a stable knee. But it may not be necessary in every case, so many patients may wish to try rehabilitation in the first instance where appropriate.

As always, prevention is key. Research has shown more than half of ACL injuries can be prevented by incorporating prevention strategies. This involves performing specific exercises to strengthen muscles in the legs, and improve movement control and landing technique.

Anthony Nasser, Senior Lecturer in Physiotherapy, University of Technology Sydney; Joshua Pate, Senior Lecturer in Physiotherapy, University of Technology Sydney, and Peter Stubbs, Senior Lecturer in Physiotherapy, University of Technology Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.