We know the importance of staying hydrated, especially in hot weather. But even for something as simple as a drink of water, conflicting advice and urban myths abound.

Is cold water really bad for your health? What about hot water from the tap? And what is “raw water”? Let’s dive in and find out.

Myth 1: Cold water is bad for you

Some recent TikToks have suggested cold water causes health problems by somehow “contracting blood vessels” and “restricting digestion”. There is little evidence for this.

While a 2001 study found 51 out of 669 women tested (7.6%) got a headache after drinking cold water, most of them already suffered from migraines and the work hasn’t been repeated since.

Cold drinks were shown to cause discomfort in people with achalasia (a rare swallowing disorder) in 2012 but the study only had 12 participants.

For most people, the temperature you drink your water is down to personal preference and circumstances. Cold water after exercise in summer or hot water to relax in winter won’t make any difference to your overall health.

Myth 2: You shouldn’t drink hot tap water

This belief has a grain of scientific truth behind it. Hot water is generally a better solvent than cold water, so may dissolve metals and minerals from pipes better. Hot water is also often stored in tanks and may be heated and cooled many times. Bacteria and other disease-causing microorganisms tend to grow better in warm water and can build up over time.

It’s better to fill your cup from the cold tap and get hot water for drinks from the kettle.

Myth 3: Bottled water is better

While bottled water might be safer in certain parts of the world due to pollution of source water, there is no real advantage to drinking bottled water in Australia and similar countries.

According to University of Queensland researchers, bottled water is not safer than tap water. It may even be tap water. Most people can’t tell the difference either. Bottled water usually costs (substantially) more than turning on the tap and is worse for the environment.

What about lead in tap water? This problem hit the headlines after a public health emergency in Flint, Michigan, in the United States. But Flint used lead pipes with a corrosion inhibitor (in this case orthophosphate) to keep lead from dissolving. Then the city switched water sources to one without a corrosion inhibitor. Lead levels rose and a public emergency was declared.

Fortunately, lead pipes haven’t been used in Australia since the 1930s. While lead might be present in some old plumbing products, it is unlikely to cause problems.

Myth 4: Raw water is naturally healthier

Some people bypass bottled and tap water, going straight to the source.

The “raw water” trend emerged a few years ago, encouraging people to drink from rivers, streams and lakes. There is even a website to help you find a local source.

Supporters say our ancestors drank spring water, so we should, too. However, our ancestors also often died from dysentery and cholera and their life expectancy was low.

While it is true even highly treated drinking water can contain low levels of things like microplastics, unless you live somewhere very remote, the risks of drinking untreated water are far higher as it is more likely to contain pollutants from the surrounding area.

Myth 5: It’s OK to drink directly from hoses

Tempting as it may be, it’s probably best not to drink from the hose when watering the plants. Water might have sat in there, in the warm sun for weeks or more potentially leading to bacterial buildup.

Similarly, while drinking water fountains are generally perfectly safe to use, they can contain a variety of bacteria. It’s useful (though not essential) to run them for a few seconds before you start to drink so as to get fresh water through the system rather than what might have been sat there for a while.

We are fortunate to be able to take safe drinking water for granted. Billions of people around the world are not so lucky.

So whether you like it hot or cold, or somewhere in between, feel free to enjoy a glass of water this summer.

Just don’t drink it from the hose.

Oliver A.H. Jones, Professor of chemistry, RMIT University

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

Corporations have used feminist language to promote their products for decades. In the 1980s, companies co-opted messaging about female autonomy to encourage women’s consumption of unhealthy commodities, such as tobacco and alcohol.

Today, feminist narratives around empowerment and women’s rights are being co-opted to market interventions that are not backed by evidence across many areas of women’s health. This includes by commercial companies, industry, mass media and well-intentioned advocacy groups.

Some of these health technologies, tests and treatments are useful in certain situations and can be very beneficial to some women.

However, promoting them to a large group of asymptomatic healthy women that are unlikely to benefit, or without being transparent about the limitations, runs the risk of causing more harm than good. This includes inappropriate medicalisation, overdiagnosis and overtreatment.

In our analysis published today in the BMJ, we examine this phenomenon in two current examples: the anti-mullerian hormone (AMH) test and breast density notification.

The AMH test

The AMH test is a blood test associated with the number of eggs in a woman’s ovaries and is sometimes referred to as the “egg timer” test.

Although often used in fertility treatment, the AMH test cannot reliably predict the likelihood of pregnancy, timing to pregnancy or specific age of menopause. The American College of Obstetricians and Gynaecologists therefore strongly discourages testing for women not seeking fertility treatment.

Despite this, several fertility clinics and online companies market the AMH test to women not even trying to get pregnant. Some use feminist rhetoric promising empowerment, selling the test as a way to gain personalised insights into your fertility. For example, “you deserve to know your reproductive potential”, “be proactive about your fertility” and “knowing your numbers will empower you to make the best decisions when family planning”.

The use of feminist marketing makes these companies appear socially progressive and champions of female health. But they are selling a test that has no proven benefit outside of IVF and cannot inform women about their current or future fertility.

Our recent study found around 30% of women having an AMH test in Australia may be having it for these reasons.

Misleading women to believe that the test can reliably predict fertility can create a false sense of security about delaying pregnancy. It can also create unnecessary anxiety, pressure to freeze eggs, conceive earlier than desired, or start fertility treatment when it may not be needed.

While some companies mention the test’s limitations if you read on, they are glossed over and contradicted by the calls to be proactive and messages of empowerment.

Breast density notification

Breast density is one of several independent risk factors for breast cancer. It’s also harder to see cancer on a mammogram image of breasts with high amounts of dense tissue than breasts with a greater proportion of fatty tissue.

While estimates vary, approximately 25–50% of women in the breast screening population have dense breasts.

Stemming from valid concerns about the increased risk of cancer, advocacy efforts have used feminist language around women’s right to know such as “women need to know the truth” and “women can handle the truth” to argue for widespread breast density notification.

However, this simplistic messaging overlooks that this is a complex issue and that more data is still needed on whether the benefits of notifying and providing additional screening or tests to women with dense breasts outweigh the harms.

Additional tests (ultrasound or MRI) are now being recommended for women with dense breasts as they have the ability to detect more cancer. Yet, there is no or little mention of the lack of robust evidence showing that it prevents breast cancer deaths. These extra tests also have out-of-pocket costs and high rates of false-positive results.

Large international advocacy groups are also sponsored by companies that will financially benefit from women being notified.

While stronger patient autonomy is vital, campaigning for breast density notification without stating the limitations or unclear evidence of benefit may go against the empowerment being sought.

Ensuring feminism isn’t hijacked

Increased awareness and advocacy in women’s health are key to overcoming sex inequalities in health care.

But we need to ensure the goals of feminist health advocacy aren’t undermined through commercially driven use of feminist language pushing care that isn’t based on evidence. This includes more transparency about the risks and uncertainties of health technologies, tests and treatments and greater scrutiny of conflicts of interests.

Health professionals and governments must also ensure that easily understood, balanced information based on high quality scientific evidence is available. This will enable women to make more informed decisions about their health.

Brooke Nickel, NHMRC Emerging Leader Research Fellow, University of Sydney and Tessa Copp, NHMRC Emerging Leader Research Fellow, University of Sydney

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