Summer is nearly here. But rather than getting out the sunscreen, some TikTokers are urging followers to chuck it out and go sunscreen-free.

They claim it’s healthier to forgo sunscreen to get the full benefits of sunshine.

Here’s the science really says.

How does sunscreen work?

Because of Australia’s extreme UV environment, most people with pale to olive skin or other risk factors for skin cancer need to protect themselves. Applying sunscreen is a key method of protecting areas not easily covered by clothes.

Sunscreen works by absorbing or scattering UV rays before they can enter your skin and damage DNA or supportive structures such as collagen.

When UV particles hit DNA, the excess energy can damage our DNA. This damage can be repaired, but if the cell divides before the mistake is fixed, it causes a mutation that can lead to skin cancers.

The most common skin cancers are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Melanoma is less common, but is the most likely to spread around the body; this process is called metastasis.

Two in three Australians will have at least one skin cancer in their lifetime, and they make up 80% of all cancers in Australia.

Around 99% of skin cancers in Australia are caused by excessive exposure to UV radiation.

Excessive exposure to UV radiation also affects the appearance of your skin. UVA rays are able to penetrate deep into the skin, where they break down supportive structures such as elastin and collagen.

This causes signs of premature ageing, such as deep wrinkling, brown or white blotches, and broken capillaries.

Sunscreen can help prevent skin cancers

Used consistently, sunscreen reduces your risk of skin cancer and slows skin ageing.

In a Queensland study, participants either used sunscreen daily for almost five years, or continued their usual use.

At the end of five years, the daily-use group had reduced their risk of squamous cell carcinoma by 40% compared to the other group.

Ten years later, the daily use group had reduced their risk of invasive melanoma by 73%

Does sunscreen block the health-promoting properties of sunlight?

The answer is a bit more complicated, and involves personalised risk versus benefit trade-offs.

First, the good news: there are many health benefits of spending time in the sun that don’t rely on exposure to UV radiation and aren’t affected by sunscreen use.

Sunscreen only filters UV rays, not visible light or infrared light (which we feel as heat). And importantly, some of the benefits of sunlight are obtained via the eyes.

Visible light improves mood and regulates circadian rhythm (which influences your sleep-wake cycle), and probably reduces myopia (short-sightedness) in children.

Infrared light is being investigated as a treatment for several skin, neurological, psychiatric and autoimmune disorders.

So what is the benefit of exposing skin to UV radiation?

Exposing the skin to the sun produces vitamin D, which is critical for healthy bones and muscles.

Vitamin D deficiency is surprisingly common among Australians, peaking in Victoria at 49% in winter and being lowest in Queensland at 6% in summer.

Luckily, people who are careful about sun protection can avoid vitamin D deficiency by taking a supplement.

Exposing the skin to UV radiation might have benefits independent of vitamin D production, but these are not proven. It might reduce the risk of autoimmune diseases such as multiple sclerosis or cause release of a chemical that could reduce blood pressure. However, there is not enough detail about these benefits to know whether sunscreen would be a problem.

What does this mean for you?

There are some benefits of exposing the skin to UV radiation that might be blunted by sunscreen. Whether it’s worth foregoing those benefits to avoid skin cancer depends on how susceptible you are to skin cancer.

If you have pale skin or other factors that increase you risk of skin cancer, you should aim to apply sunscreen daily on all days when the UV index is forecast to reach 3.

If you have darker skin that rarely or never burns, you can go without daily sunscreen – although you will still need protection during extended times outdoors.

For now, the balance of evidence suggests it’s better for people who are susceptible to skin cancer to continue with sun protection practices, with vitamin D supplementation if needed.

Katie Lee, PhD Candidate, Dermatology Research Centre, The University of Queensland and Rachel Neale, Principal research fellow, QIMR Berghofer Medical Research Institute

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

Mitochondria are tiny structures in cells that convert the food we eat into the energy our cells need to function.

Mitochondrial disease (or mito for short) is a group of conditions that affect this ability to generate the energy organs require to work properly. There are many different forms of mito and depending on the form, it can disrupt one or more organs and can cause organ failure.

There is no cure for mito. But an IVF procedure called mitochondrial donation now offers hope to families affected by some forms of mito that they can have genetically related children free from mito.

After a law to allow mitochondrial donation in Australia was passed in 2022, scientists are now preparing for a clinical trial to see if mitochondrial donation is safe and works.

What is mitochondrial disease?

There are two types of mitochondrial disease.

One is caused by faulty genes in the nuclear DNA, the DNA we inherit from both our parents and which makes us who we are.

The other is caused by faulty genes in the mitochondria’s own DNA. Mito caused by faulty mitochondrial DNA is passed down through the mother. But the risk of disease is unpredictable, so a mother who is only mildly affected can have a child who develops serious disease symptoms.

Mitochondrial disease is the most common inherited metabolic condition affecting one in 5,000 people.

Some people have mild symptoms that progress slowly, while others have severe symptoms that progress rapidly. Mito can affect any organ, but organs that need a lot of energy such as brain, muscle and heart are more often affected than other organs.

Mito that manifests in childhood often involves multiple organs, progresses rapidly, and has poor outcomes. Of all babies born each year in Australia, around 60 will develop life-threatening mitochondrial disease.

What is mitochondrial donation?

Mitochondrial donation is an experimental IVF-based technique that offers people who carry faulty mitochondrial DNA the potential to have genetically related children without passing on the faulty DNA.

It involves removing the nuclear DNA from the egg of someone who carries faulty mitochondrial DNA and inserting it into a healthy egg donated by someone not affected by mito, which has had its nuclear DNA removed.

The resulting egg has the nuclear DNA of the intending parent and functioning mitochondria from the donor. Sperm is then added and this allows the transmission of both intending parents’ nuclear DNA to the child.

A child born after mitochondrial donation will have genetic material from the three parties involved: nuclear DNA from the intending parents and mitochondrial DNA from the egg donor. As a result the child will likely have a reduced risk of mito, or no risk at all.

This highly technical procedure requires specially trained scientists and sophisticated equipment. It also requires both the person with mito and the egg donor to have hormone injections to stimulate the ovaries to produce multiple eggs. The eggs are then retrieved in an ultrasound-guided surgical procedure.

Mitochondrial donation has been pioneered in the United Kingdom where a handful of babies have been born as a result. To date there have been no reports about whether they are free of mito.

Maeve’s Law

After three years of public consultation The Mitochondrial Donation Law Reform (Maeve’s Law) Bill 2021 was passed in the Australian Senate in 2022, making mitochondrial donation legal in a research and clinical trial setting.

Maeve’s law stipulates strict conditions including that clinics need a special licence to perform mitochondrial donation.

To make sure mitochondrial donation works and is safe before it’s introduced into Australian clinical practice, the law also specifies that initial licences will be issued for pre-clinical and clinical trial research and training.

We’re expecting one such licence to be issued for the mitoHOPE (Healthy Outcomes Pilot and Evaluation) program, which we are part of, to perfect the technique and conduct a clinical trial to make sure mitochondrial donation is safe and effective.

Before starting the trial, a preclinical research and training program will ensure embryologists are trained in “real-life” clinical conditions and existing mitochondrial donation techniques are refined and improved. To do this, many human eggs are needed.

The need for donor eggs

One of the challenges with mitochondrial donation is sourcing eggs. For the preclinical research and training program, frozen eggs can be used, but for the clinical trial “fresh” eggs will be needed.

One possible source of frozen eggs is from people who have stored eggs they don’t intend to use.

A recent study looked at data on the outcomes of eggs stored at a Melbourne clinic from 2012 to 2021. Over the ten-year period, 1,132 eggs from 128 patients were discarded. No eggs were donated to research because the clinics where the eggs were stored did not conduct research requiring donor eggs.

However, research shows that among people with stored eggs, the number one choice for what to do with eggs they don’t need is to donate them to research.

This offers hope that, given the opportunity, those who have eggs stored that they don’t intend to use might be willing to donate them to mitochondrial donation preclinical research.

As for the “fresh” eggs needed in the future clinical trial, this will require individuals to volunteer to have their ovaries stimulated and eggs retrieved to give those people impacted by mito a chance to have a healthy baby. Egg donors may be people who are friends or relatives of those who enter the trial, or it might be people who don’t know someone affected by mito but would like to help them conceive.

At this stage, the aim is to begin enrolling participants in the clinical trial in the next 12 to 18 months. However this may change depending on when the required licences and ethics approvals are granted.

Karin Hammarberg, Senior Research Fellow, Global and Women’s Health, School of Public Health & Preventive Medicine, Monash University; Catherine Mills, Professor of Bioethics, Monash University; Mary Herbert, Professor, Anatomy & Developmental Biology, Monash University, and Molly Johnston, Research fellow, Monash Bioethics Centre, Monash University

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