At one time or another, you’ve probably come across someone who is lactose intolerant and might experience some unpleasant gut symptoms if they have dairy. Maybe it’s you – food intolerances are estimated to affect up to 25% of Australians.

Meanwhile, cow’s milk allergy is one of the most common food allergies in infants and young children, affecting around one in 100 infants.

But what’s the difference between food allergies and food intolerances? While they might seem alike, there are some fundamental differences between the two.

What is an allergy?

Australia has one of the highest rates of food allergies in the world. Food allergies can develop at any age but are more common in children, affecting more than 10% of one-year-olds and 6% of children at age ten.

A food allergy happens when the body’s immune system mistakenly reacts to certain foods as if they were dangerous. The most common foods that trigger allergies include eggs, peanuts and other nuts, milk, shellfish, fish, soy and wheat.

Mild to moderate signs of food allergy include a swollen face, lips or eyes; hives or welts on your skin; or vomiting. A severe allergic reaction (called anaphylaxis) can cause trouble breathing, persistent dizziness or collapse.

What is an intolerance?

Food intolerances (sometimes called non-allergic reactions) are also reactions to food, but they don’t involve your immune system.

For example, lactose intolerance is a metabolic condition that happens when the body doesn’t produce enough lactase. This enzyme is needed to break down the lactose (a type of sugar) in dairy products.

Food intolerances can also include reactions to natural chemicals in foods (such as salicylates, found in some fruits, vegetables, herbs and spices) and problems with artificial preservatives or flavour enhancers.

Symptoms of food intolerances can include an upset stomach, headaches and fatigue, among others.

Food intolerances don’t cause life-threatening reactions (anaphylaxis) so are less dangerous than allergies in the short term, although they can cause problems in the longer term such as malnutrition.

We don’t know a lot about how common food intolerances are, but they appear to be more commonly reported than allergies. They can develop at any age.

It can be confusing

Some foods, such as peanuts and tree nuts, are more often associated with allergy. Other foods or ingredients, such as caffeine, are more often associated with intolerance.

Meanwhile, certain foods, such as cow’s milk and wheat or gluten (a protein found in wheat, rye and barley), can cause both allergic and non-allergic reactions in different people. But these reactions, even when they’re caused by the same foods, are quite different.

For example, children with a cow’s milk allergy can react to very small amounts of milk, and serious reactions (such as throat swelling or difficulty breathing) can happen within minutes. Conversely, many people with lactose intolerance can tolerate small amounts of lactose without symptoms.

There are other differences too. Cow’s milk allergy is more common in children, though many infants will grow out of this allergy during childhood.

Lactose intolerance is more common in adults, but can also sometimes be temporary. One type of lactose intolerance, secondary lactase deficiency, can be caused by damage to the gut after infection or with medication use (such as antibiotics or cancer treatment). This can go away by itself when the underlying condition resolves or the person stops using the relevant medication.

Whether an allergy or intolerance is likely to be lifelong depends on the food and the reason that the child or adult is reacting to it.

Allergies to some foods, such as milk, egg, wheat and soy, often resolve during childhood, whereas allergies to nuts, fish or shellfish, often (but not always) persist into adulthood. We don’t know much about how likely children are to grow out of different types of food intolerances.

How do you find out what’s wrong?

If you think you may have a food allergy or intolerance, see a doctor.

Allergy tests help doctors find out which foods might be causing your allergic reactions (but can’t diagnose food intolerances). There are two common types: skin prick tests and blood tests.

In a skin prick test, doctors put tiny amounts of allergens (the things that can cause allergies) on your skin and make small pricks to see if your body reacts.

A blood test checks for allergen-specific immunoglobulin E (IgE) antibodies in your blood that show if you might be allergic to a particular food.

Food intolerances can be tricky to figure out because the symptoms depend on what foods you eat and how much. To diagnose them, doctors look at your health history, and may do some tests (such as a breath test). They may ask you to keep a record of foods you eat and timing of symptoms.

A temporary elimination diet, where you stop eating certain foods, can also help to work out which foods you might be intolerant to. But this should only be done with the help of a doctor or dietitian, because eliminating particular foods can lead to nutritional deficiencies, especially in children.

Is there a cure?

There’s currently no cure for food allergies or intolerances. For allergies in particular, it’s important to strictly avoid allergens. This means reading food labels carefully and being vigilant when eating out.

However, researchers are studying a treatment called oral immunotherapy, which may help some people with food allergies become less sensitive to certain foods.

Whether you have a food allergy or intolerance, your doctor or dietitian can help you to make sure you’re eating the right foods.

Victoria Gibson, a Higher Degree by Research student and Research Officer at the School of Nursing, Midwifery and Social Work at the University of Queensland, and Rani Scott-Farmer, a Senior Research Assistant at the University of Queensland, contributed to this article.

Jennifer Koplin, Group Leader, Childhood Allergy & Epidemiology, The University of Queensland and Desalegn Markos Shifti, Postdoctoral Research Fellow, Child Health Research Centre, Faculty of Medicine, The University of Queensland

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

According to the World Health Organization, about 280 million people worldwide have depression and about one billion have a mental health problem of any kind.

People living in the ancient world also had mental health problems. So, how did they deal with them?

As we’ll see, some of their insights about mental health are still relevant today, even though we might question some of their methods.

1. Our mental state is important

Mental health problems such as depression were familiar to people in the ancient world. Homer, the poet famous for the Iliad and Odyssey who lived around the eighth century BC, apparently died after wasting away from depression.

Already in the late fifth century BC, ancient Greek doctors recognised that our health partly depends on the state of our thoughts.

In the Epidemics, a medical text written in around 400BC, an anonymous doctor wrote that our habits about our thinking (as well as our lifestyle, clothing and housing, physical activity and sex) are the main determinants of our health.

2. Mental health problems can make us ill

Also writing in the Epidemics, an anonymous doctor described one of his patients, Parmeniscus, whose mental state became so bad he grew delirious, and eventually could not speak. He stayed in bed for 14 days before he was cured. We’re not told how.

Later, the famous doctor Galen of Pergamum (129-216AD) observed that people often become sick because of a bad mental state:

It may be that under certain circumstances ‘thinking’ is one of the causes that bring about health or disease because people who get angry about everything and become confused, distressed and frightened for the slightest reason often fall ill for this reason and have a hard time getting over these illnesses.

Galen also described some of his patients who suffered with their mental health, including some who became seriously ill and died. One man had lost money:

He developed a fever that stayed with him for a long time. In his sleep he scolded himself for his loss, regretted it and was agitated until he woke up. While he was awake he continued to waste away from grief. He then became delirious and developed brain fever. He finally fell into a delirium that was obvious from what he said, and he remained in this state until he died.

3. Mental illness can be prevented and treated

In the ancient world, people had many different ways to prevent or treat mental illness.

The philosopher Aristippus, who lived in the fifth century BC, used to advise people to focus on the present to avoid mental disturbance:

concentrate one’s mind on the day, and indeed on that part of the day in which one is acting or thinking. Only the present belongs to us, not the past nor what is anticipated. The former has ceased to exist, and it is uncertain if the latter will exist.

The philosopher Clinias, who lived in the fourth century BC, said that whenever he realised he was becoming angry, he would go and play music on his lyre to calm himself.

Doctors had their own approaches to dealing with mental health problems. Many recommended patients change their lifestyles to adjust their mental states. They advised people to take up a new regime of exercise, adopt a different diet, go travelling by sea, listen to the lectures of philosophers, play games (such as draughts/checkers), and do mental exercises equivalent to the modern crossword or sudoku.

For instance, the physician Caelius Aurelianus (fifth century AD) thought patients suffering from insanity could benefit from a varied diet including fruit and mild wine.

Doctors also advised people to take plant-based medications. For example, the herb hellebore was given to people suffering from paranoia. However, ancient doctors recognised that hellebore could be dangerous as it sometimes induced toxic spasms, killing patients.

Other doctors, such as Galen, had a slightly different view. He believed mental problems were caused by some idea that had taken hold of the mind. He believed mental problems could be cured if this idea was removed from the mind and wrote:

a person whose illness is caused by thinking is only cured by taking care of the false idea that has taken over his mind, not by foods, drinks, [clothing, housing], baths, walking and other such (measures).

Galen thought it was best to deflect his patients’ thoughts away from these false ideas by putting new ideas and emotions in their minds:

I put fear of losing money, political intrigue, drinking poison or other such things in the hearts of others to deflect their thoughts to these things […] In others one should arouse indignation about an injustice, love of rivalry, and the desire to beat others depending on each person’s interest.

4. Addressing mental health needs effort

Generally speaking, the ancients believed keeping our mental state healthy required effort. If we were anxious or angry or despondent, then we needed to do something that brought us the opposite of those emotions.

This can be achieved, they thought, by doing some activity that directly countered the emotions we are experiencing.

For example, Caelius Aurelianus said people suffering from depression should do activities that caused them to laugh and be happy, such as going to see a comedy at the theatre.

However, the ancients did not believe any single activity was enough to make our mental state become healthy. The important thing was to make a wholesale change to one’s way of living and thinking.

When it comes to experiencing mental health problems, we clearly have a lot in common with our ancient ancestors. Much of what they said seems as relevant now as it did 2,000 years ago, even if we use different methods and medicines today.

If this article has raised issues for you, or if you’re concerned about someone you know, call Lifeline on 13 11 14.

Konstantine Panegyres, McKenzie Postdoctoral Fellow, researching Greco-Roman antiquity, The University of Melbourne

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