Every year, almost 1 in 6 Americans gets a foodborne illness, and about 3,000 people die from it, according to Centers for Disease Control and Prevention estimates. Picnics and parties where food sits out for hours are a common source, but heat waves and power outages are another silently growing threat.

As global temperatures rise, the risk of foods going bad during blackouts in homes or stores or during transit in hot weather rises with them. Elena Naumova, an epidemiologist and data scientist at Tufts University, explains the risk and what you need to know to stay safe.

What does climate change have to do with foodborne illness?

The link between foodborne illness and climate change is quite straightforward: The pathogens that cause many foodborne infections are sensitive to temperature. That’s because warm, wet weather conditions stimulate bacterial growth.

Three main factors govern the spread of foodborne illness: 1) the abundance, growth, range and survival of pathogens in crops, livestock and the environment; 2) the transfer of these pathogens to food; and 3) human exposure to the pathogens.

Safety measures like warning labels and product recalls can help slow the spread of harmful bacteria and parasites, but these measures don’t always evolve rapidly enough to keep pace with the changing risk.

One growing problem is that heat waves, wildfires and severe storms are increasingly triggering power outages, which in turn affect food storage and food handling practices in stores, production and distribution sites and homes. A review of federal data in 2022 found that major U.S. power outages linked to severe weather had doubled over the previous two decades. California often experiences smaller-scale outages during heat waves and periods of high wildfire risk.

This can happen on the hottest and, in some areas, most humid days, creating ideal conditions for bacteria to grow.

Which causes of foodborne illness are increasing with the heat?

Nationwide, many types of foodborne infection peak in warm summer months.

Cyclospora, a tiny parasite that causes intestinal infections and is transmitted through food or water contaminated with feces, often on imported vegetables and fruits, peaks in early June.

The bacteria Campylobacter, a common cause of diarrhea that’s often linked to undercooked meat; Vibrio, linked to eating raw or undercooked shellfish; Salmonella, which causes diarrhea and is linked to animal feces; and STEC, a common type of E. coli, peak in mid-July. And the parasite Cyptosporidium, germ Listeria and bacteria Shigella peak in mid-August.

Many of these infections cause upset stomach, but they can also lead to severe diarrhea, dehydration, vomiting and even longer-term illnesses, such as meningitis and multiple organ failures.

In our studies, my colleagues and I have also found that food recalls increase during summer months.

Typically, the U.S. sees about 70 foodborne outbreaks per month, with about two of them resulting in a food recall. In summer, the number of outbreaks can exceed 100 per month, and the number of recall-related outbreaks goes up to six per month, increasing from 3% to 6% of all reported and investigated outbreaks nationwide.

The rate of individual infections can also easily double or triple the annual average during summer months.

Precisely estimating infection numbers is very challenging because the vast majority of foodborne illness outbreaks – an estimated 80% of illnesses and 56% of hospitalizations – are not attributed to known pathogens due to insufficient testing, and many foodborne illnesses are not even reported to the health authorities.

What types of food should people worry about?

Watch out for perishable products, including meat, poultry, fish, dairy and eggs, along with anything labeled as requiring refrigeration. How warm a food item can get before becoming risky varies, so the simplest rule for keeping food safe is to follow food labels and instructions.

The CDC website emphasizes four basic rules to prevent food poisoning at home: clean, separate, cook and chill.

It also offers some guidelines for when the power goes out, starting with keeping refrigerator and freezer doors closed. “A full freezer will keep food safe for 48 hours (24 hours if half-full) without power if you don’t open the door. Your refrigerator will keep food safe for up to four hours without power if you don’t open the door,” it says.

After four hours without power or a cooling source, the CDC recommends that most meat, dairy, leftovers and cut fruits and vegetables in the refrigerator be thrown out.

Unfortunately, you cannot see, smell or taste many harmful pathogens that cause foodborne illness, so it’s better to be safe than sorry. Rule of thumb: When in doubt, throw it out.

What’s the best response if a person gets sick from food?

If you do get sick, it can be hard to pinpoint the culprit. Harmful bacteria can take anywhere from a few hours to several days to make you sick. And people respond in different ways, so the same food might not make everyone ill.

Check with your doctor if you think you have food poisoning. Get tested so your case will be reported. That helps public health authorities get a better sense of the extent of infections. The full extent of infections is typically vastly underreported.

I recommend checking health department websites, like Washington state’s, for more advice, and check on food recalls during the hot months.

Elena N. Naumova, Professor of Epidemiology and Data Science, Tufts University

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

Anyone who has suffered from jet lag or struggled after turning the clock forward or back an hour for daylight saving time knows all about what researchers call your biological clock, or circadian rhythm – the “master pacemaker” that synchronizes how your body responds to the passing of one day to the next.

This “clock” is made up of about 20,000 neurons in the hypothalamus, the area near the center of the brain that coordinates your body’s unconscious functions, like breathing and blood pressure. Humans aren’t the only beings that have an internal clock system: All vertebrates – or mammals, birds, reptiles, amphibians and fish – have biological clocks, as do plants, fungi and bacteria. Biological clocks are why cats are most active at dawn and dusk, and why flowers bloom at certain times of day.

Circadian rhythms are also essential to health and well-being. They govern your body’s physical, mental and behavioral changes over each 24-hour cycle in response to environmental cues like light and food. They’re why more heart attacks and strokes occur early in the morning. They’re also why mice that are missing their biological clocks age faster and have shorter lifespans, and people with a mutation in their circadian clock genes have abnormal sleep patterns. Chronic misalignment of your circadian rhythm with external cues, as seen in night-shift workers, can lead to a wide range of physical and mental disorders, including obesity, Type 2 diabetes, cancer and cardiovascular diseases.

In short, there is ample evidence that your biological clock is critical to your health. And chronobiologists like me are studying how the day-night cycle affects your body to better understand how you can modify your behaviors to use your internal clock to your advantage.

How biological rhythms affect your health

Your biological clock affects your health by regulating your sleep-wake cycles and fluctuations in blood pressure and body temperature. It does this primarily by syncing your endocrine system to environmental light-dark cycles so that certain hormones are released in certain amounts at certain times of day.

The pineal grand in your brain, for example, produces melatonin, a hormone that helps regulate sleep in response to darkness. Doctors advise reducing exposure to artificial blue light from electronic devices before bedtime because it can disrupt melatonin secretion and sleep quality.

Your circadian rhythm also affects your metabolism. Among other things, sleep helps you regulate leptin, a hormone that controls appetite. Your leptin levels fluctuate throughout the day according to a rhythm set by your circadian clock. Insufficient or irregular sleep can disrupt leptin production, which can make us hungrier and lead to weight gain.

In recent years, researchers have discovered even more ways your circadian clock can affect your health. For example, there is now research suggesting that eating at set times of day, or time-restricted feeding, can prevent obesity and metabolic diseases. Depression and other mood disorders may also be linked to dysfunctional circadian control that lead to changes in how your genes are expressed.

The time of day when you take your medicine can also affect how well it works and how severe any side effects might be. Likewise, your biological clock is a potential target for cancer chemotherapies and anti-obesity treatments.

And finally, even your personality might be shaped by whether your internal clock make you a “morning person” or a “night person.”

Getting the most out of exercise

Circadian clocks also provide a potential answer to when is the best time of day to maximize the benefits of physical exercise.

To study this, my colleagues and I collected blood and tissue samples from the brains, hearts, muscles, livers and fat of mice that exercised either before breakfast in the early morning or after dinner in the late evening. We used a tool called a mass spectrometer to detect approximately 600 to 900 molecules each organ produced. These metabolites served as real-time snapshots of how the mice responded to exercise at specific times of day.

We stitched these snapshots together to create a map of how exercise in the morning versus evening affected each of the mice’s different organ systems – what we called an atlas of exercise metabolism.

Using this atlas, we saw that time of day affects how each organ uses energy during exercise. For instance, we found that early morning exercise reduced blood glucose levels more than late evening exercise. Exercise in the late evening, however, allowed the mice to benefit from energy they stored from their meals and increased their endurance.

Of course, mice and humans have many differences along with their similarities. For one, mice are more active at night than during the day. Still, we believe that our findings could help researchers better understand how exercise affects your health and, if timed appropriately, can be optimized based on time of day to meet your personal health goals.

Getting along with your biological clock

I believe that the field of chronobiology is growing, and we will produce even more research providing practical applications and insights into health and well-being in the future.

In my own work, for example, a better understanding of how exercising at different times of day affects your body could help tailor exercise plans to maximize specific benefits for patients with obesity, Type 2 diabetes and other diseases.

There is still much to learn about how your circadian clock works. But in the meantime, there are some tried and true ways people can synchronize their internal clocks for better health. These include regular exposure to sunlight to trigger the endocrine system to produce vitamin D, staying active during the day so you fall asleep more easily at night and avoiding caffeine and reducing your exposure to artificial light before bedtime.

Shogo Sato, Assistant Professor of Biology, Texas A&M University

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