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On Nutrition

It’s royal news that set the internet aflutter (no, not messy buns, the May 19 wedding, or Charlotte and George’s new little brother): Prince Harry’s fiancée, actress Meghan Markle, wards off jet lag by drinking lots of water, eating when the locals do after she lands — and taking probiotics. Are these nutrition myths, or is there something to them?

Jet lag is no joke, and it may be more than a damper on the beginning and end of your trip. Research shows that disconnecting from our circadian rhythms — which not only tune into the 24-hour cycle of day and night, but also patterns of activity and rest — could also affect our metabolic health, possibly even increasing our risk of developing type 2 diabetes.

As for hydrating and adjusting your eating schedule, that’s solid advice. Mild dehydration is common during air travel, and can make the physical symptoms of jet lag feel worse. The remedy is to drink plenty of fluids before, during and after your flight, and to avoid alcohol, which is itself dehydrating, and caffeine, which disturbs sleep.

If you’re staying at your destination for more than a day or two, sleeping and eating in accordance with your new time zone as soon as you arrive helps your body clock — or circadian rhythms — acclimate. Eating when the locals do, getting outside in natural light, staying awake until the local bedtime and getting up in the morning can help speed your adjustment.

Probiotics and health

So what do probiotics have to do with jet lag? Probiotics are bacteria and other microorganisms that can be beneficial when we have enough of them. One of the benefits they promote is a balanced, healthy gut microbiota — aka the more than 100 trillion microbes that live in our gut, or large intestine. Some research has even found that our gut microbes help the genes that regulate our body clocks. In laboratory studies, mice treated with antibiotics — which disrupt the gut microbiota — had altered circadian rhythms. That’s intriguing, but it’s not quite enough evidence to make probiotics a go-to for jet lag prevention.

What scientific research has established is that probiotics can support our general health in a handful of important ways. They help our immune system function properly and stave off harmful microorganisms (such as those responsible for foodborne illness). They aid in digestion by breaking down some of the food we can’t process (such as so-called “fermentable fiber”). They produce vitamins — notably vitamin K, but also smaller amounts of some of the B vitamins — and help us absorb nutrients.

Where to find probiotics

Probiotics can come from supplements as well as many fermented foods — although it’s a common myth that fermented foods and probiotics are interchangeable. Fermented foods and beverages are made by extensive microbial growth, and they’ve been around for thousands of years. But not all fermented foods retain their live microbes (or “live and active cultures”), and even those that do may still not meet the criteria of a true probiotic.

Fermented foods that retain live microbes when we eat them include fresh kimchi, sauerkraut and sour dill pickles, along with yogurt, kefir, kombucha, miso, some cheeses, water- or brine-cured olives, traditional salami and European-style dry fermented sausages, and craft beers that haven’t been filtered or heated. When fermented foods are processed — through baking, pasteurization or filtering — the live microbes are destroyed. This occurs in tempeh, most soy sauce, most beer and wine, sourdough bread, chocolate, shelf-stable kimchi and sauerkraut, and fresh cheeses including cottage cheese. Many of the bacteria in aged cheeses also die during storage.

Determining whether a food contains living microbes is fairly black-or-white. What’s trickier is figuring out which microbe-carrying foods are probiotics. To be considered a probiotic, these foods must have enough specific species that have been shown to have health benefits. But some species haven’t been studied adequately to determine what specific benefits they provide, and in some fermented foods, the exact microbes present can vary from batch to batch. A few fermented foods that contain true probiotics are Nancy’s yogurt, Activia yogurt, GoodBelly probiotic drinks and Dahlicious Lassi yogurt drinks.

While it’s true that fermented foods offer health benefits, it’s still unclear whether those benefits come from the live microbes themselves, nutrients in the food, or the way microbes transform foods by digesting parts of them. For example: Some people with lactose intolerance can’t drink milk without distress but can eat yogurt, because microbes have digested some of its lactose.

The bottom line

Should you travel like a princess (or duchess, technically) with probiotics in your carry-on? It’s unclear from a scientific point of view whether taking a probiotic directly affects your gut microbes in a way that supports regulation of your circadian rhythms. But jet-lag symptoms can include nausea and upset stomach, and the desire to stay as healthy as possible is heightened when we’re far from home. Since probiotics do help support our digestive and immune systems, there’s likely little downside to taking them when you travel, although you might want to test them out before you go.