What’s the difference between physical and chemical sunscreens? And which one should you choose?
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Sun exposure can accelerate ageing, cause skin burns, erythema (a skin reaction), skin cancer, melasmas (or sun spots) and other forms of hyperpigmentation – all triggered by solar ultraviolet radiation.
Approximately 80% of skin cancer cases in people engaged in outdoor activities are preventable by decreasing sun exposure. This can be done in lots of ways including wearing protective clothing or sunscreens.
But not all sunscreens work in the same way. You might have heard of “physical” and “chemical” sunscreens. What’s the difference and which one is right for you?
How sunscreens are classified
Sunscreens are grouped by their use of active inorganic and organic ultraviolet (UV) filters. Chemical sunscreens use organic filters such as cinnamates (chemically related to cinnamon oil) and benzophenones. Physical sunscreens (sometimes called mineral sunscreens) use inorganic filters such as titanium and zinc oxide.
These filters prevent the effects of UV radiation on the skin.
Organic UV filters are known as chemical filters because the molecules in them change to stop UV radiation reaching the skin. Inorganic UV filters are known as physical filters, because they work through physical means, such as blocking, scattering and reflection of UV radiation to prevent skin damage.
Nano versus micro
The effectiveness of the filters in physical sunscreen depends on factors including the size of the particle, how it’s mixed into the cream or lotion, the amount used and the refraction index (the speed light travels through a substance) of each filter.
When the particle size in physical sunscreens is large, it causes the light to be scattered and reflected more. That means physical sunscreens can be more obvious on the skin, which can reduce their cosmetic appeal.
Nanoparticulate forms of physical sunscreens (with tiny particles smaller than 100 nanometers) can improve the cosmetic appearance of creams on the skin and UV protection, because the particles in this size range absorb more radiation than they reflect. These are sometimes labelled as “invisible” zinc or mineral formulations and are considered safe.
So how do chemical sunscreens work?
Chemical UV filters work by absorbing high-energy UV rays. This leads to the filter molecules interacting with sunlight and changing chemically.
When molecules return to their ground (or lower energy) state, they release energy as heat, distributed all over the skin. This may lead to uncomfortable reactions for people with skin sensitivity.
Generally, UV filters are meant to stay on the epidermis (the first skin layer) surface to protect it from UV radiation. When they enter into the dermis (the connective tissue layer) and bloodstream, this can lead to skin sensitivity and increase the risk of toxicity. The safety profile of chemical UV filters may depend on whether their small molecular size allows them to penetrate the skin.
Chemical sunscreens, compared to physical ones, cause more adverse reactions in the skin because of chemical changes in their molecules. In addition, some chemical filters, such as dibenzoylmethane tend to break down after UV exposure. These degraded products can no longer protect the skin against UV and, if they penetrate the skin, can cause cell damage.
Due to their stability – that is, how well they retain product integrity and effectiveness when exposed to sunlight – physical sunscreens may be more suitable for children and people with skin allergies.
Although sunscreen filter ingredients can rarely cause true allergic dermatitis, patients with photodermatoses (where the skin reacts to light) and eczema have higher risk and should take care and seek advice.
What to look for
The best way to check if you’ll have a reaction to a physical or chemical sunscreen is to patch test it on a small area of skin.
And the best sunscreen to choose is one that provides broad-spectrum protection, is water and sweat-resistant, has a high sun protection factor (SPF), is easy to apply and has a low allergy risk.
Health authorities recommend sunscreen to prevent sun damage and cancer. Chemical sunscreens have the potential to penetrate the skin and may cause irritation for some people. Physical sunscreens are considered safe and effective and nanoparticulate formulations can increase their appeal and ease of use.
Yousuf Mohammed, Dermatology researcher, The University of Queensland and Khanh Phan, Postdoctoral research associate, Frazer Institute, The University of Queensland
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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New research finds many infant food products make claims that don’t match the main ingredients
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From images of fruit to claims of being “sugar-free”, manufacturers of baby and toddler foods try to convince parents their products are a healthy choice, convenient and good for their child’s development.
But as our new research shows, many are not.
We studied the packaging of 210 foods for infants and toddlers found in New Zealand supermarkets. Every package featured claims, and many showed images of fruit and vegetables, which didn’t reflect the main ingredients used.
The first thousand days of a child’s life are critical. This is when their brains and bodies are growing faster than they will at any other time in their lives. Optimal nutrition is essential at this time for healthy growth, wellbeing, development and to shape eating patterns for life.
It’s also a time when parents are often busy – and industry knows this. Manufacturers play on convenience and use marketing to badge foods that don’t support good health as “nutritious”.
On-pack claims are a powerful marketing tool, and they are effective. They influence consumer perceptions, drive purchasing decisions and can create a health halo around products that don’t deserve it.
Getty Images Cluttered with claims
The foods we studied had an average of between seven to eight claims on their packaging, with the worst offenders carrying up to 15 claims.
The most common claims were about ingredients that were not in the foods – “free from additives”, “free from colours”. This type of claim can distract parents from what is actually in the food, which could be a high sugar content or highly processed ingredients.
Other claims promoted the food as good for development or an easy choice, playing into parents’ desire to do what’s best for their child and to accommodate busy family lifestyles. Parents shouldn’t have to sift through all these claims to find the information they need to select a healthy option.
Of all the foods, 60% featured images of fruit and 40% displayed images of vegetables, but most didn’t contain any whole fruits and vegetables. Snack foods featuring vegetables often only contain tiny amounts of vegetable juice or powder, and foods featuring fruit images typically contain processed fruit sugars such as pastes and concentrates.
Of most concern was that one in five contained less than 5% fruit. Images of fruits and vegetables give parents and carers the perception of healthiness and influence their purchasing decisions. But should the industry selling these products be allowed to do this when they contain no whole fruits and vegetables at all?
Product names don’t match main ingredients
We also found product names to be misleading. In more than half of the savoury meals, the name did not reflect the main ingredients accurately. Meats or nutrient-dense ingredients such as spinach or legumes were often highlighted in the name but only present in small amounts.
It is a similar story across the Tasman. Australian researchers assessed 330 products available in supermarkets and also found prolific claims and inaccurate names dominating the packaging.
With an average of eight claims on Australian products and a third of foods touting names that don’t accurately reflect ingredients, it’s clear the current bi-national rules developed and administered by Food Standards Australia New Zealand (FSANZ) for on-pack marketing are not sufficient.
Unfortunately, many packaged infant and toddler foods in Australia and New Zealand do not support healthy eating habits. In Australia, only about a quarter of products were found to comply with World Health Organization nutritional recommendations. As yet unpublished research for New Zealand products found only about a third meet these standards. They shouldn’t be marketed as though they do.
We have an opportunity for reform. Earlier this year, food ministers in Australia and New Zealand asked FSANZ to review regulations around claims and names used on products to make sure they don’t mislead and enable caregivers to make informed choices.
This is a great first step. It’s now up to FSANZ to get the rules right. We need comprehensive changes to ensure these foods are marketed responsibly. At a minimum this must include:
- no health, nutrition or related claims to be allowed on infant and toddler foods
- images of fruits and vegetables only permitted where whole fruits and vegetables form a substantial part of the product
- and product names that accurately reflect the ingredients of a product.
The authors acknowledge the following co-authors of research mentioned in this article: Berit Follong, Baylee Wilde and Maria Ferreria in New Zealand, and Andrea Schmidtke, Maree Scully, Rachael Jinnette and Linh Le in Australia.
Sally Mackay, Senior Lecturer in Epidemiology and Biostatistics, University of Auckland, Waipapa Taumata Rau and Jane Martin, Senior Fellow, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Celery vs Parsley – Which is Healthier?
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Our Verdict
When comparing celery to parsley, we picked the parsley.
Why?
Firstly, you may be thinking: “What kind of a comparison is this?! Parsley is a seasoning or a garnish; who uses it as a salad option option?!” and the answer is that nobody can stop you from using herbs as a main greenery option, and in fact, we recommend it (both for adding a lot of flavor to your plate, and getting in a lot of nutrients).
So, with that in mind, let’s get to it:
In terms of macros, parsley has 2x the fiber for 2x the carbs and 5x the protein, winning in this category easily.
In the category of vitamins, celery is not higher in any vitamins, while parsley has a lot more of vitamins A, B1, B2, B3, B5, B6, B7, B9, C, E, and K, sweeping its second round completely.
Looking at minerals, celery does have more selenium, while parsley has a lot more calcium, copper, iron, magnesium, manganese, phosphorus, potassium, and zinc, convincingly winning its third round in a row.
In other considerations, they both are great sources of polyphenols, though celery (albeit notably the leaves thereof, not the stalks so much) does have more flavonoids specifically, and may arguably pick up a point here.
Adding up the sections makes for a clear overall win for parsley, but by all means do enjoy either or both, as diversity is best!
(Unless you are allergic to celery, in which case, definitely do stick the parsley!)
Want to learn more?
You might like:
Invigorating Sabzi Khordan ← another great way to enjoy parsley as main ingredient rather than just a seasoning
Enjoy!
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Intermittent fasting doesn’t have an edge for weight loss, but might still work for some
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Intermittent fasting has become a buzzword in nutrition circles, with many people looking to it as a way to lose weight or improve their health.
But new research from the Cochrane Collaboration shows intermittent fasting is no more effective for weight loss than receiving traditional dietary advice or even doing nothing at all.
In this international review, researchers assessed 22 studies involving 1,995 adults who were classified as overweight (with a body mass index of 25–29.9 kg/m²) or obese (with a BMI of 30 kg/m² or above) to assess the effectiveness of intermittent fasting for up to 12 months.
The authors found, when compared to energy restricted dieting, intermittent fasting doesn’t seem to work for people who are overweight or obese and are trying to lose weight. However they note intermittent fasting may still be a reasonable option for some people.
fcafotodigital/Getty Images Remind me, what’s intermittent fasting?
Intermittent fasting is a tool for weight management, which includes three main strategies:
- alternate day fasting, where every second day is reduced to low or no energy intake
- periodic fasting or the 5:2 diet, where one or two days of the week are spent with low or no energy intake
- time-restricted eating or the 16:8 diet, where daily energy intake is reduced to a shorter window, usually between eight and ten waking hours.
What did previous research show?
Previous reviews have found differences between types of intermittent fasting.
Alternate day fasting, for example, resulted in more weight loss when compared to time-restricted eating.
This is because participants who fasted every second day consumed about 20% less energy than those following time-restricted eating.
What did the Cochrane review find?
Cochrane review use gold-standard techniques to give an objective overview of the evidence. This review looked at 22 individual randomised controlled trials published between 2016 and 2024 from North America, Europe, China, Australia and South America.
The trials compared the outcomes of almost 2,000 adults who were classified as being overweight or obese. These participants either:
- received standard dietary advice, such as restricting calories or eating different types of foods
- practised intermittent fasting
- received either regular dietary advice, no intervention or were on a wait list.
The authors found:
1. Intermittent fasting was no better than getting dietary advice
The researchers found intermittent fasting and receiving dietary advice to restrict energy intake led to similar levels of weight loss.
This finding was based on 21 studies involving 1,713 people, with the researchers measuring the change from the participants’ starting weight.
Dietary advice (from registered dietitians or trained researchers) could include an eating plan focused on fruit, vegetables, whole grains and seafood, restricting calories, or any specific dietary advice for weight loss.
The amount of weight the participants lost ranged from a 10% loss to a 1% gain, with either intermittent fasting or dietary advice.
These findings are similar to several recent meta-analyses which found intermittent fasting is no better than dieting.
Previous research has found most of the alternate day fasting and periodic diet studies leads to about 6% to 7% weight loss. This is compared to very low energy “shake” diets (about 10%), GLP-1 medications (15% to 20%) and surgery (above 20%).
The review also found intermittent fasting likely makes little difference to a person’s quality of life, based on only three studies.
2. Intermittent fasting was no better than doing nothing
The researchers found intermittent fasting and no intervention led to similar levels of weight loss. This finding was based on six studies involving 448 people.
In the intermittent fasting studies, participants experienced about 5% weight loss. The “no intervention” or control group lost about 2% of their original weight.
In research, a 3% difference in weight loss is not considered clinically meaningful. That’s why the authors of this review concluded intermittent fasting is no more effective for weight loss than doing nothing at all.
However, the result for the “no intervention” condition could be due to the Hawthorne effect: the tendency for people to behave differently because they know they are being watched, such as in a clinical trial.
What are the review’s limitations?
There were few large, high-quality randomised controlled trials to draw on.
Only six studies were included in the part of the review which compared intermittent fasting and doing nothing. Two of these focused on time-restricted eating, which is arguably the least effective weight-loss strategy. One looked at the effects of fasting for one day per week. The other three were intermittent fasting studies, each with varying control groups, where some received guidance and others did not.
Also, the review only looked at studies where the interventions lasted between six and 12 months. It’s possible intermittent fasting strategies could be a long-term tool for weight maintenance. So we need to do more research, and ideally studies of longer duration.
What about the other health benefits of fasting?
Studies have found intermittent fasting can lower blood pressure, improve fertility, and reduce the incidence of metabolic syndrome which refers to a group of conditions that increase the risk of cardiovascular disease.
In one 2024 study, researchers found intermittent fasting may lead to changes in metabolism and the gut that restrict how cancer develops. Another study from 2025 found intermittent fasting could improve the metabolic health of shift workers.
So if you’re practising or considering intermittent fasting, the current evidence suggests it can be a safe and effective way to manage your weight.
But for any weight loss strategy to work, it needs to align with your personal preferences. And it’s best to consult a health-care professional before starting any new diet, especially if you have any underlying health conditions.
Evelyn Parr, Research Fellow in Exercise Metabolism and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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We’re only using a fraction of health workers’ skills. This needs to change
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Roles of health professionals are still unfortunately often stuck in the past. That is, before the shift of education of nurses and other health professionals into universities in the 1980s. So many are still not working to their full scope of practice.
There has been some expansion of roles in recent years – including pharmacists prescribing (under limited circumstances) and administering a wider range of vaccinations.
But the recently released paper from an independent Commonwealth review on health workers’ “scope of practice” identifies the myriad of barriers preventing Australians from fully benefiting from health professionals’ skills.
These include workforce design (who does what, where and how roles interact), legislation and regulation (which often differs according to jurisdiction), and how health workers are funded and paid.
There is no simple quick fix for this type of reform. But we now have a sensible pathway to improve access to care, using all health professionals appropriately.
A new vision for general practice
I recently had a COVID booster. To do this, I logged onto my general practice’s website, answered the question about what I wanted, booked an appointment with the practice nurse that afternoon, got jabbed, was bulk-billed, sat down for a while, and then went home. Nothing remarkable at all about that.
But that interaction required a host of facilitating factors. The Victorian government regulates whether nurses can provide vaccinations, and what additional training the nurse requires. The Commonwealth government has allowed the practice to be paid by Medicare for the nurse’s work. The venture capitalist practice owner has done the sums and decided allocating a room to a practice nurse is economically rational.
The future of primary care is one involving more use of the range of health professionals, in addition to GPs.
It would be good if my general practice also had a physiotherapist, who I could see if I had back pain without seeing the GP, but there is no Medicare rebate for this. This arrangement would need both health professionals to have access to my health record. There also needs to be trust and good communication between the two when the physio might think the GP needs to be alerted to any issues.
This vision is one of integrated primary care, with health professionals working in a team. The nurse should be able to do more than vaccination and checking vital signs. Do I really need to see the GP every time I need a prescription renewed for my regular medication? This is the nub of the “scope of practice” issue.
How about pharmacists?
An integrated future is not the only future on the table. Pharmacy owners especially have argued that pharmacists should be able to practise independently of GPs, prescribing a limited range of medications and dispensing them.
This will inevitably reduce continuity of care and potentially create risks if the GP is not aware of what other medications a patient is using.
But a greater role for pharmacists has benefits for patients. It is often easier and cheaper for the patient to see a pharmacist, especially as bulk billing rates fall, and this is one of the reasons why independent pharmacist prescribing is gaining traction.
It’s often easier for a patient to see a pharmacist than a GP. PeopleImages.com – Yuri A/Shutterstock Every five years or so the government negotiates an agreement with the Pharmacy Guild, the organisation of pharmacy owners, about how much pharmacies will be paid for dispensing medications and other services. These agreements are called “Community Pharmacy Agreements”. Paying pharmacists independent prescribing may be part of the next agreement, the details of which are currently being negotiated.
GPs don’t like competition from this new source, even though there will be plenty of work around for GPs into the foreseeable future. So their organisations highlight the risks of these changes, reopening centuries old turf wars dressed up as concerns about safety and risk.
Who pays for all this?
Funding is at the heart of disputes about scope of practice. As with many policy debates, there is merit on both sides.
Clearly the government must increase its support for comprehensive general practice. Existing funding of fee-for-service medical benefits payments must be redesigned and supplemented by payments that allow practices to engage a range of other health professionals to create health-care teams.
This should be the principal direction of primary care reform, and the final report of the scope of practice review should make that clear. It must focus on the overall goal of better primary care, rather than simply the aspirations of individual health professionals, and working to a professional’s full scope of practice in a team, not a professional silo.
In parallel, governments – state and federal – must ensure all health professionals are used to their best of their abilities. It is a waste to have highly educated professionals not using their skills fully. New funding arrangements should facilitate better access to care from all appropriately qualified health professionals.
In the case of prescribing, it is possible to reconcile the aspirations of pharmacists and the concerns of GPs. New arrangements could be that pharmacists can only renew medications if they have agreements with the GP and there is good communication between them. This may be easier in rural and suburban areas, where the pharmacists are better known to the GPs.
The second issues paper points to the complexity of achieving scope of practice reforms. However, it also sets out a sensible path to improve access to care using all health professionals appropriately.
Stephen Duckett, Honorary Enterprise Professor, School of Population and Global Health, and Department of General Practice and Primary Care, The University of Melbourne
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Strong Women Stay Slim – by Dr. Miriam Nelson & Dr. Sarah Wernick
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We previously reviewed “Strong Women Stay Young” by the same authors, and this time it’s about weight loss (or, when one is at one’s desired weight: weight maintenance).
Unlike most guidebooks with the word “slim” in the title, the focus here is not on diet, but (as the subtitle promises) exercises. Specifically, strength training.
This idea was quite cutting-edge for its time (publication date: 1999) when we were barely out of “cardio for weight loss”, and the authors present plenty of good science that holds up the scrutiny of the present day. Regular 10almonds readers will know this, but it’s mostly about how whereas an abundance of fat in the body (in one’s fat cells that is, not necessarily in one’s diet) triggers a slowing of the metabolism in attempt to help you survive the famine it thinks you’re surely preparing for, muscle mass has a metabolic “cost” to maintain, and so the metabolism increases accordingly (burning stored fat as fuel, or—dose dependent—at least not adding to it, because calories consumed were used immediately).
On the topic of diet, that’s a weak point of the book. While it’s not the focus, there is some advice (and some recipes), and it’s what you might expect for a book from the previous century. Which is not to say that it’s all bad; they do recommend fibrous vegetables and whole grains—they just also aren’t that keen on fruit, add milk (skimmed milk, no less) to so many things, include a recipe for beef sandwiches, etc. It’s not good, and unlike other parts of the book, did not stand the test of time (indeed, much of their dietary advice would be thoroughly refuted by 2005).
Bottom line: if you’d like to lose weight, the exercise side of this will be very beneficial. For dietary advice, we recommend things more in line with modern scientific consensus.
Click here to check out Strong Women Stay Slim, and stay strong and slim!
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Progesterone Menopausal HRT: When, Why, And How To Benefit
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Progesterone doesn’t get talked about as much as other sex hormones, so what’s its deal? Dr. Heather Hirsch explains:
Menopausal progesterone
Dr. Hirsch considers progesterone essential for menopausal women who are taking estrogen and have an intact uterus, to keep conditions at bay such as endometriosis or even uterine cancer.
However, she advises it is not critical in those without a uterus, unless there was a previous case of one of the above conditions.
10almonds addition: on the other hand, progesterone can still be beneficial from a metabolic and body composition standpoint, so do speak with your endocrinologist about it.
As an extra bonus: while not soporific (it won’t make you sleepy), taking progesterone at night will improve the quality of your sleep once you do sleep, so that’s a worthwhile thing for many!
Dr. Hirsch also discusses the merits of continuous vs cyclic use; continuous maintains the above sleep benefits, for example, while cyclic use can help stabilize menstrual patterns in late perimenopause and early menopause.
For more on these things, plus discussion of different types of progesterone, enjoy:
Click Here If The Embedded Video Doesn’t Load Automatically!
Want to learn more?
You might also like to read:
- What Does “Balance Your Hormones” Even Mean?
- What You Should Have Been Told About The Menopause Beforehand
- HRT: Bioidentical vs Animal – A Tale Of Two Approaches
Take care!
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