Kaitlin Day, RMIT University and Sharayah Carter, RMIT University

Intermittent fasting has gained popularity in recent years as a dietary approach with potential health benefits. So you might have been surprised to see headlines last week suggesting the practice could increase a person’s risk of death from heart disease.

The news stories were based on recent research which found a link between time-restricted eating, a form of intermittent fasting, and an increased risk of death from cardiovascular disease, or heart disease.

So what can we make of these findings? And how do they measure up with what else we know about intermittent fasting and heart disease?

The study in question

The research was presented as a scientific poster at an American Heart Association conference last week. The full study hasn’t yet been published in a peer-reviewed journal.

The researchers used data from the National Health and Nutrition Examination Survey (NHANES), a long-running survey that collects information from a large number of people in the United States.

This type of research, known as observational research, involves analysing large groups of people to identify relationships between lifestyle factors and disease. The study covered a 15-year period.

It showed people who ate their meals within an eight-hour window faced a 91% increased risk of dying from heart disease compared to those spreading their meals over 12 to 16 hours. When we look more closely at the data, it suggests 7.5% of those who ate within eight hours died from heart disease during the study, compared to 3.6% of those who ate across 12 to 16 hours.

We don’t know if the authors controlled for other factors that can influence health, such as body weight, medication use or diet quality. It’s likely some of these questions will be answered once the full details of the study are published.

It’s also worth noting that participants may have eaten during a shorter window for a range of reasons – not necessarily because they were intentionally following a time-restricted diet. For example, they may have had a poor appetite due to illness, which could have also influenced the results.

Other research

Although this research may have a number of limitations, its findings aren’t entirely unique. They align with several other published studies using the NHANES data set.

For example, one study showed eating over a longer period of time reduced the risk of death from heart disease by 64% in people with heart failure.

Another study in people with diabetes showed those who ate more frequently had a lower risk of death from heart disease.

A recent study found an overnight fast shorter than ten hours and longer than 14 hours increased the risk dying from of heart disease. This suggests too short a fast could also be a problem.

But I thought intermittent fasting was healthy?

There are conflicting results about intermittent fasting in the scientific literature, partly due to the different types of intermittent fasting.

There’s time restricted eating, which limits eating to a period of time each day, and which the current study looks at. There are also different patterns of fast and feed days, such as the well-known 5:2 diet, where on fast days people generally consume about 25% of their energy needs, while on feed days there is no restriction on food intake.

Despite these different fasting patterns, systematic reviews of randomised controlled trials (RCTs) consistently demonstrate benefits for intermittent fasting in terms of weight loss and heart disease risk factors (for example, blood pressure and cholesterol levels).

RCTs indicate intermittent fasting yields comparable improvements in these areas to other dietary interventions, such as daily moderate energy restriction.

So why do we see such different results?

RCTs directly compare two conditions, such as intermittent fasting versus daily energy restriction, and control for a range of factors that could affect outcomes. So they offer insights into causal relationships we can’t get through observational studies alone.

However, they often focus on specific groups and short-term outcomes. On average, these studies follow participants for around 12 months, leaving long-term effects unknown.

While observational research provides valuable insights into population-level trends over longer periods, it relies on self-reporting and cannot demonstrate cause and effect.

Relying on people to accurately report their own eating habits is tricky, as they may have difficulty remembering what and when they ate. This is a long-standing issue in observational studies and makes relying only on these types of studies to help us understand the relationship between diet and disease challenging.

It’s likely the relationship between eating timing and health is more complex than simply eating more or less regularly. Our bodies are controlled by a group of internal clocks (our circadian rhythm), and when our behaviour doesn’t align with these clocks, such as when we eat at unusual times, our bodies can have trouble managing this.

So, is intermittent fasting safe?

There’s no simple answer to this question. RCTs have shown it appears a safe option for weight loss in the short term.

However, people in the NHANES dataset who eat within a limited period of the day appear to be at higher risk of dying from heart disease. Of course, many other factors could be causing them to eat in this way, and influence the results.

When faced with conflicting data, it’s generally agreed among scientists that RCTs provide a higher level of evidence. There are too many unknowns to accept the conclusions of an epidemiological study like this one without asking questions. Unsurprisingly, it has been subject to criticism.

That said, to gain a better understanding of the long-term safety of intermittent fasting, we need to be able follow up individuals in these RCTs over five or ten years.

In the meantime, if you’re interested in trying intermittent fasting, you should speak to a health professional first.

Kaitlin Day, Lecturer in Human Nutrition, RMIT University and Sharayah Carter, Lecturer Nutrition and Dietetics, RMIT University

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

From today, February 3, pregnant women in Australia will be eligible for a free RSV vaccine under the National Immunisation Program.

This vaccine is designed to protect young infants from severe RSV (respiratory syncytial virus). It does so by generating the production of antibodies against RSV in the mother, which then travel across the placenta to the baby.

While the RSV vaccine is a new addition to the National Immunisation Program, it’s one of three vaccines provided free for pregnant women under the program, alongside ones for influenza and whooping cough. Each offers important protection for newborn babies.

The RSV vaccine

RSV is the most common cause of lower respiratory infections (bronchiolitis and pneumonia) in infants. It’s estimated that of every 100 infants born in Australia each year, at least two will be hospitalised with RSV by six months of age.

RSV infection is most common roughly between March and August in the southern hemisphere, but infection can occur year-round, especially in tropical areas.

The vaccine works by conferring passive immunity (from the mother) as opposed to active immunity (the baby’s own immune response). By the time the baby is born, their antibodies are sufficient to protect them during the first months of life when they are most vulnerable to severe RSV disease.

The RSV vaccine registered for use in pregnant women in Australia, Abrysvo, has been used since 2023 in the Americas and Europe. Real-world experience there shows it’s working well.

For example, over the 2024 RSV season in Argentina, it was found to prevent 72.7% of lower respiratory tract infections caused by RSV and requiring hospitalisation in infants aged 0–3 months, and 68% among those aged 0–6 months. This research noted three deaths from RSV, all in infants whose mothers did not receive the RSV vaccine during pregnancy.

This was similar to protection seen in a large multinational clinical trial that compared babies born to mothers who received this RSV vaccine with babies born to mothers who received a placebo. This study found the vaccine prevented 82.4% of severe cases of RSV in infants aged under three months, and 70% under six months, and that the vaccine was safe.

In addition to the maternal vaccine, nirsevimab, a long-acting monoclonal antibody, provides effective protection against severe RSV disease. It’s delivered to the baby by an intramuscular injection, usually in the thigh.

Nirsevimab is recommended for babies born to women who did not receive an RSV vaccine during pregnancy, or who are born within two weeks of their mother having received the shot (most likely if they’re born prematurely). It may also be recommended for babies who are at higher risk of RSV due to a medical condition, even if their mother was vaccinated.

Nirsevimab is not funded under the National Immunisation Program, but is covered under various state and territory-based programs for infants of mothers who fall into the above categories.

But now we have a safe and effective RSV vaccine for pregnancy, all pregnant women should be encouraged to receive it as the first line of prevention. This will maximise the number of babies protected during their first months of life.

Flu and whooping cough

It’s also important pregnant women continue to receive flu and whooping cough vaccines in 2025. Like the RSV vaccine, these protect infants by passing antibodies from mother to baby.

There has been a large whooping cough outbreak in Australia in recent months, including a death of a two-month-old infant in Queensland in November 2024.

The whooping cough vaccine, given in combination with diphtheria and tetanus, prevents more than 90% of whooping cough cases in babies too young to receive their first whooping cough vaccine dose.

Similarly, influenza can be deadly in young babies, and maternal flu vaccination substantially reduces hospital visits associated with influenza for babies under six months. Flu can also be serious for pregnant women, so the vaccine offers important protection for the mother as well.

COVID vaccines are safe in pregnancy, but unless a woman is otherwise eligible, they’re not routinely recommended. You can discuss this with your health-care provider.

When and where can you get vaccinated?

Pregnant women can receive these vaccines during antenatal visits through their GP or in a specialised antenatal clinic.

The flu vaccine is recommended at any time during pregnancy, the whooping cough vaccine from 20 weeks (ideally before 32 weeks), and the RSV vaccine from 28 weeks (before 36 weeks).

It’s safe to receive multiple vaccinations at the same clinic visit.

We know vaccination rates have declined in a variety of groups since the pandemic, and there’s evidence emerging that suggests this trend has occurred in pregnant women too.

A recent preprint (a study yet to be peer-reviewed) found a decrease of nearly ten percentage points in flu vaccine coverage among pregnant women in New South Wales, from 58.8% in 2020 to 49.1% in 2022. The research showed a smaller drop of 1.4 percentage points for whooping cough, from 79% in 2020 to 77.6% in 2022.

It’s important to work to improve vaccination rates during pregnancy to give babies the best protection in their first months of life.

We know pregnant women would like to receive information about new and routine maternal vaccines early in pregnancy. In particular, many pregnant women want to understand how vaccines are tested for safety, and their effectiveness, which was evident during COVID.

GPs and midwives are trusted sources of information on vaccines in pregnancy. There’s also information available online on Sharing Knowledge About Immunisation, a collaboration led by the National Centre for Immunisation Research and Surveillance.

Archana Koirala, Paediatrician and Infectious Diseases Specialist, University of Sydney; Bianca Middleton, Senior Research Fellow, Menzies School of Health Research; Margie Danchin, Professor of Paediatrics and vaccinologist, Royal Childrens Hospital, University of Melbourne and Murdoch Childrens Research Institute (MCRI); Associate Dean International, University of Melbourne, Murdoch Children’s Research Institute; Peter McIntyre, Professor in Women’s and Children’s Health, University of Otago, and Rebecca Doyle, Adjunct Research Fellow, School of Nursing, Midwifery and Social Work, The University of Queensland

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