When British TV doctor Michael Mosley died last year in Greece after walking in extreme heat, local police said “heat exhaustion” was a contributing factor.

Since than a coroner could not find a definitive cause of death but said this was most likely due to an un-identified medical reason or heat stroke.

Heat exhaustion and heat stroke are two illnesses that relate to heat.

So what’s the difference?

A spectrum of conditions

Heat-related illnesses range from mild to severe. They’re caused by exposure to excessive heat, whether from hot conditions, physical exertion, or both. The most common ones include:

• heat oedema: swelling of the hands, feet and ankles
• heat cramps: painful, involuntary muscle spasms usually after exercise
• heat syncope: fainting due to overheating
• heat exhaustion: when the body loses water due to excessive sweating, leading to a rise in core body temperature (but still under 40°C). Symptoms include lethargy, weakness and dizziness, but there’s no change to consciousness or mental clarity
• heat stroke: a medical emergency when the core body temperature is over 40°C. This can lead to serious problems related to the nervous system, such as confusion, seizures and unconsciousness including coma, leading to death.

As you can see from the diagram below, some symptoms of heat stroke and heat exhaustion overlap. This makes it hard to recognise the difference, even for medical professionals.

How does this happen?

The human body is an incredibly efficient and adaptable machine, equipped with several in-built mechanisms to keep our core temperature at an optimal 37°C.

But in healthy people, regulation of body temperature begins to break down when it’s hotter than about 31°C with 100% humidity (think Darwin or Cairns) or about 38°C with 60% humidity (typical of other parts of Australia in summer).

This is because humid air makes it harder for sweat to evaporate and take heat with it. Without that cooling effect, the body starts to overheat.

Once the core temperature rises above 37°C, heat exhaustion can set in, which can cause intense thirst, weakness, nausea and dizziness.

If the body heat continues to build and the core body temperature rises above 40°C, a much more severe heat stroke could begin. At this point, it’s a life-threatening emergency requiring immediate medical attention.

At this temperature, our proteins start to denature (like an egg on a hotplate) and blood flow to the intestines stops. This makes the gut very leaky, allowing harmful substances such as endotoxins (toxic substances in some bacteria) and pathogens (disease causing microbes) to leak into the bloodstream.

The liver can’t detoxify these fast enough, leading to the whole body becoming inflamed, organs failing, and in the worst-case scenario, death.

Who’s most at risk?

People doing strenuous exercise, especially if they’re not in great shape, are among those at risk of heat exhaustion or heat stroke. Others at risk include those exposed to high temperatures and humidity, particularly when wearing heavy clothing or protective gear.

Outdoor workers such as farmers, firefighters and construction workers are at higher risk too. Certain health conditions, such as diabetes, heart disease, or lung conditions (such as COPD or chronic obstructive pulmonary disease), and people taking blood pressure medications, can also be more vulnerable.

Adults over 65, infants and young children are especially sensitive to heat as they are less able to physically cope with fluctuations in heat and humidity.

How are these conditions managed?

The risk of serious illness or death from heat-related conditions is very low if treatment starts early.

For heat exhaustion, have the individual lie down in a cool, shady area, loosen or remove excess clothing, and cool them by fanning, moistening their skin, or immersing their hands and feet in cold water.

As people with heat exhaustion almost always are dehydrated and have low electrolytes (certain minerals in the blood), they will usually need to drink fluids.

However, emergency hospital care is essential for heat stroke. In hospital, health professionals will focus on stabilising the patient’s:

• airway (ensure no obstructions, for instance, vomit)
• breathing (look for signs of respiratory distress or oxygen deprivation)
• circulation (check pulse, blood pressure and signs of shock).

Meanwhile, they will use rapid-cooling techniques including immersing the whole body in cold water, or applying wet ice packs covering the whole body.

Take home points

Heat-related illnesses, such as heat stroke and heat exhaustion, are serious health conditions that can lead to severe illness, or even death.

With climate change, heat-related illness will become more common and more severe. So recognising the early signs and responding promptly are crucial to prevent serious complications.

Matthew Barton, Senior lecturer, School of Nursing and Midwifery, Griffith University and Michael Todorovic, Associate Professor of Medicine, Bond University

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

Iron deficiency is common and can be debilitating. It mainly affects women. One in three premenopausal women are low in iron compared to just 5% of Australian men. Iron deficiency particularly affects teenage girls, women who do a lot of exercise and those who are pregnant.

The body needs iron to make new red blood cells, and to support energy production, the immune system and cognitive function. If you’re low, you may experience a range of symptoms including fatigue, weakness, shortness of breath, headache, irregular heartbeat and reduced concentration.

If a blood test shows you’re iron deficient, your doctor may recommend you start taking an oral iron supplement. But should you take a tablet or a liquid? With food or not? And when is the best time of day?

Here are some tips to help you work out how, when and what iron supplement to take.

How do I pick the right iron supplement?

The iron in your body is called “elemental iron”. Choosing the right oral supplement and dose will depend on how much elemental iron it has – your doctor will advise exactly how much you need.

The sweet spot is between 60-120 mg of elemental iron. Any less and the supplement won’t be effective in topping up your iron levels. Any higher and you risk gastrointestinal symptoms such as diarrhoea, cramping and stomach pain.

In Australia, iron salts are the most common oral supplements because they are cheap, effective and come in different delivery methods (tablets, capsules, liquid formulas). The iron salts you are most likely to find in your local chemist are ferrous sulfate (~20% elemental iron), ferrous gluconate (~12%) and ferrous fumarate (~33%).

These formulations all work similarly, so your choice should come down to dose and cost.

Many multivitamins may look like an iron supplement, but it’s important to note they usually have too little iron – usually less than 20 mg – to correct an iron deficiency.

Should I take tablets or liquid formulas?

Iron contained within a tablet is just as well absorbed as iron found in a liquid supplement. Choosing the right one usually comes down to personal preference.

The main difference is that liquid formulas tend to contain less iron than tablets. That means you might need to take more of the product to get the right dose, so using a liquid supplement could work out to be more expensive in the long term.

What should I eat with my iron supplement?

Research has shown you will absorb more of the iron in your supplement if you take it on an empty stomach. But this can cause more gastrointestinal issues, so might not be practical for everyone.

If you do take your supplement with meals, it’s important to think about what types of food will boost – rather than limit – iron absorption. For example, taking the supplement alongside vitamin C improves your body’s ability to absorb it.

Some supplements already contain vitamin C. Otherwise you could take the supplement along with a glass of orange juice, or other vitamin C-rich foods.

On the other hand, tea, coffee and calcium all decrease the body’s ability to absorb iron. So you should try to limit these close to the time you take your supplement.

Should I take my supplement in the morning or evening?

The best time of day to take your supplement is in the morning. The body can absorb significantly more iron earlier in the day, when concentrations of hepcidin (the main hormone that regulates iron) are at their lowest.

Exercise also affects the hormone that regulates iron. That means taking your iron supplement after exercising can limit your ability to absorb it. Taking your supplement in the hours following exercise will mean significantly poorer absorption, especially if you take it between two and five hours after you stop.

Our research has shown if you exercise every day, the best time to take your supplement is in the morning before training, or immediately after (within 30 minutes).

My supplements are upsetting my stomach. What should I do?

If you experience gastrointestinal side effects such as diarrhoea or cramps when you take iron supplements, you may want to consider taking your supplement every second day, rather than daily.

Taking a supplement every day is still the fastest way to restore your iron levels. But a recent study has shown taking the same total dose can be just as effective when it’s taken on alternate days. For example, taking a supplement every day for three months works as well as every second day for six months. This results in fewer side effects.

Oral iron supplements can be a cheap and easy way to correct an iron deficiency. But ensuring you are taking the right product, under the right conditions, is crucial for their success.

It’s also important to check your iron levels prior to commencing iron supplementation and do so only under medical advice. In large amounts, iron can be toxic, so you don’t want to be consuming additional iron if your body doesn’t need it.

If you think you may be low on iron, talk to your GP to find out your best options.

Alannah McKay, Postdoctoral Research Fellow, Sports Nutrition, Australian Catholic University

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