Around one in ten Australians say they follow a gluten-free diet.

This means eliminating common foods – such as bread, pasta and noodles – that contain gluten, a protein found mainly in wheat, barley and rye.

Not everyone who follows a gluten-free diet has an underlying condition. But if you experience nausea, bloating or stomach pain after eating gluten, it could be the sign of a gluten intolerance, or coeliac disease.

While gluten intolerance and coeliac disease share many similar symptoms, one can cause intestinal damage and malnutrition. So, what’s the difference?

What is coeliac disease?

Coeliac disease is an autoimmune disease. This means the body mistakenly starts attacking healthy cells and tissue – in this case, in the small intestine – causing inflammation.

It affects around one in 70 Australians, but only 20% of this group are diagnosed.

If you have coeliac disease, eating foods that contain gluten can damage your villi, structures in the small intestine that help the body absorb nutrients.

Following a meal containing gluten, you may experience digestive problems including diarrhoea, bloating, nausea, gas and abdominal pain.

Gluten can also cause non-digestive symptoms such as brain fog, headaches, dermatitis herpetiformis (an itchy, blistery skin rash), joint pain and fatigue.

In the long term, untreated coeliac disease can lead to malnutrition because the damaged villi can’t absorb nutrients from food. It can also reduce bone mineral density and has been linked to neurological disorders such as epilepsy and dementia.

How is coeliac disease diagnosed?

For an accurate diagnosis, you must not have eliminated gluten from your diet yet. This is so its effect on your digestive system can be measured.

A diagnosis involves blood tests followed by biopsies of the small intestine using an endoscope (an instrument with a light that can look inside the body).

Blood tests look for antigens – markers of a reaction to gluten – while the biopsy inspects any damage to the villi in the intestine.

In some cases, a capsule endoscopy, where a pill-sized camera is swallowed, is used to look at the intestine and observe for damage.

What about gluten intolerance?

People with gluten intolerance experience similar symptoms to coeliac disease. The difference is, after consuming gluten, there is no autoimmune response or intestinal damage.

Gluten intolerance is sometimes known as non-coeliac gluten sensitivity.

An estimated 1% of Australians live with a gluten intolerance, but only 12 in every 100 of this group are diagnosed by a doctor.

Doctors will rule out coeliac disease and wheat allergies as a first step for a person with symptoms related to eating gluten.

Once these have been ruled out, a gluten-free diet trial, supervised by an accredited practising dietitian, might be recommended to see if symptoms improve.

A formal diagnosis of gluten intolerance can only be confirmed using a highly complex dietary trial that compares the effect of gluten and a placebo over at least eight weeks.

This form of scientific study is very labour-intensive and not very common.

So instead many people just choose to eliminate gluten, without a diagnosis.

Extreme sensitivity to gluten

Coeliac disease is more severe than gluten intolerance and sensitivity can vary among those diagnosed.

Even traces of gluten can trigger symptoms. This means a strict, lifelong, gluten-free diet essential.

It also means people with coeliac disease have to be careful about cross-contamination. For example, using the same knife, chopping board or toaster to cut or toast gluten-free bread and regular bread can transfer gluten particles and cause a reaction.

According to the latest studies, consuming just 50mg of gluten per day is enough to cause intestinal damage for people with coeliac disease.

For context, a slice of whole-wheat bread contains about 4,800mg of gluten, meaning 50mg is around 1/100th of a slice of bread.

A small amount of gluten won’t affect someone with gluten intolerance in the same way. They may have temporary symptoms, but won’t experience intestinal damage.

However, the symptoms and their severity can vary from person to person, depending on their individual sensitivity.

Should I cut out gluten, just in case?

You might be wondering if there is a downside to avoiding gluten, if you don’t have coeliac disease or an intolerance.

There can be.

Grain foods that contain gluten are rich in essential nutrients such as fibre, folate, iron and B-group vitamins.

Avoiding gluten when you don’t need to can lead to nutritional deficiencies.

Gluten-free products can also be more expensive and are sometimes higher in sugar, salt and fat to help compensate for texture and taste.

Before making any changes to your diet, it is best to speak with an accredited practising dietitian to make sure you’re not missing out on important nutrients.

So, what if you have symptoms?

Common signs of a gluten intolerance or coeliac disease include bloating, diarrhoea or constipation, and stomach pain. Both conditions can trigger non-gastrointestinal symptoms such as headaches, fatigue and joint pain.

If these symptoms sound familiar, it’s best to speak to a health-care professional who may test you for coeliac disease and/or a wheat allergy before eliminating gluten from your diet.

Remember, self-diagnosing and removing gluten without proper guidance might do you more harm than good.

If your symptoms concern you, speak to your GP, a gastroenterologist or a qualified dietitian. Dietitians Australia has a list of accredited practising dietitians.

Yasmine Probst, Professor, School of Medical, Indigenous and Health Sciences. Advanced Accredited Practising Dietitian, University of Wollongong and Olivia Wills, Associate Lecturer, Nutrition and Dietetics, University of Wollongong

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

Intermittent fasting has become a popular dietary approach to help people lose or manage their weight. It has also been promoted as a way to reset metabolism, control chronic disease, slow ageing and improve overall health.

Meanwhile, some research suggests intermittent fasting may offer a different way for the brain to access energy and provide protection against neurodegenerative diseases like Alzheimer’s disease.

This is not a new idea – the ancient Greeks believed fasting enhanced thinking. But what does the modern-day evidence say?

First, what is intermittent fasting?

Our diets – including calories consumed, macronutrient composition (the ratios of fats, protein and carbohydrates we eat) and when meals are consumed – are factors in our lifestyle we can change. People do this for cultural reasons, desired weight loss or potential health gains.

Intermittent fasting consists of short periods of calorie (energy) restriction where food intake is limited for 12 to 48 hours (usually 12 to 16 hours per day), followed by periods of normal food intake. The intermittent component means a re-occurrence of the pattern rather than a “one off” fast.

Food deprivation beyond 24 hours typically constitutes starvation. This is distinct from fasting due to its specific and potentially harmful biochemical alterations and nutrient deficiencies if continued for long periods.

4 ways fasting works and how it might affect the brain

The brain accounts for about 20% of the body’s energy consumption.

Here are four ways intermittent fasting can act on the body which could help explain its potential effects on the brain.

1. Ketosis

The goal of many intermittent fasting routines is to flip a “metabolic switch” to go from burning predominately carbohydrates to burning fat. This is called ketosis and typically occurs after 12–16 hours of fasting, when liver and glycogen stores are depleted. Ketones – chemicals produced by this metabolic process – become the preferred energy source for the brain.

Due to this being a slower metabolic process to produce energy and potential for lowering blood sugar levels, ketosis can cause symptoms of hunger, fatigue, nausea, low mood, irritability, constipation, headaches, and brain “fog”.

At the same time, as glucose metabolism in the brain declines with ageing, studies have shown ketones could provide an alternative energy source to preserve brain function and prevent age-related neurodegeneration disorders and cognitive decline.

Consistent with this, increasing ketones through supplementation or diet has been shown to improve cognition in adults with mild cognitive decline and those at risk of Alzheimer’s disease respectively.

2. Circadian syncing

Eating at times that don’t match our body’s natural daily rhythms can disrupt how our organs work. Studies in shift workers have suggested this might also make us more prone to chronic disease.

Time-restricted eating is when you eat your meals within a six to ten-hour window during the day when you’re most active. Time-restricted eating causes changes in expression of genes in tissue and helps the body during rest and activity.

A 2021 study of 883 adults in Italy indicated those who restricted their food intake to ten hours a day were less likely to have cognitive impairment compared to those eating without time restrictions.

3. Mitochondria

Intermittent fasting may provide brain protection through improving mitochondrial function, metabolism and reducing oxidants.

Mitochondria’s main role is to produce energy and they are crucial to brain health. Many age-related diseases are closely related to an energy supply and demand imbalance, likely attributed to mitochondrial dysfunction during ageing.

Rodent studies suggest alternate day fasting or reducing calories by up to 40% might protect or improve brain mitochondrial function. But not all studies support this theory.

4. The gut-brain axis

The gut and the brain communicate with each other via the body’s nervous systems. The brain can influence how the gut feels (think about how you get “butterflies” in your tummy when nervous) and the gut can affect mood, cognition and mental health.

In mice, intermittent fasting has shown promise for improving brain health by increasing survival and formation of neurons (nerve cells) in the hippocampus brain region, which is involved in memory, learning and emotion.

There’s no clear evidence on the effects of intermittent fasting on cognition in healthy adults. However one 2022 study interviewed 411 older adults and found lower meal frequency (less than three meals a day) was associated with reduced evidence of Alzheimer’s disease on brain imaging.

Some research has suggested calorie restriction may have a protective effect against Alzheimer’s disease by reducing oxidative stress and inflammation and promoting vascular health.

When we look at the effects of overall energy restriction (rather than intermittent fasting specifically) the evidence is mixed. Among people with mild cognitive impairment, one study showed cognitive improvement when participants followed a calorie restricted diet for 12 months.

Another study found a 25% calorie restriction was associated with slightly improved working memory in healthy adults. But a recent study, which looked at the impact of calorie restriction on spatial working memory, found no significant effect.

Bottom line

Studies in mice support a role for intermittent fasting in improving brain health and ageing, but few studies in humans exist, and the evidence we have is mixed.

Rapid weight loss associated with calorie restriction and intermittent fasting can lead to nutrient deficiencies, muscle loss, and decreased immune function, particularly in older adults whose nutritional needs may be higher.

Further, prolonged fasting or severe calorie restriction may pose risks such as fatigue, dizziness, and electrolyte imbalances, which could exacerbate existing health conditions.

If you’re considering intermittent fasting, it’s best to seek advice from a health professional such as a dietitian who can provide guidance on structuring fasting periods, meal timing, and nutrient intake. This ensures intermittent fasting is approached in a safe, sustainable way, tailored to individual needs and goals.

Hayley O’Neill, Assistant Professor, Faculty of Health Sciences and Medicine, Bond University

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