Pistachios are surging in popularity across the U.S. as more Americans turn to the popular green snack for flavor and health benefits.Once prized in ancient Persia, pistachios are now showing up in everything from chocolate bars to coffee drinks. The tree nuts have ancient origins and have long been popular in the Middle East and Asia. EATING ONE TYPE OF NUT DAILY COULD LOWER 'BAD' CHOLESTEROL, IMPROVE HEART HEALTH, STUDY FINDSThey were mentioned in the Old Testament and treated as a luxury in ancient Persia. Now, pistachios are having a moment in the U.S.Janelle Connell, a registered dietitian and personalized nutrition expert at the health testing company Viome, shared thoughts about the pistachio craze.Pistachios offer gut benefits, in addition to healthy fats and protein, Connell said.These nuts "help your microbiome make compounds that support digestion and immunity," she told Fox News Digital.SAVORY OATMEAL BOWLS STIR UP A NEW BREAKFAST CRAZE WITH EGGS, CHEESE AND SPICEOne ounce of pistachios, measuring roughly 50 kernels, is packed with 6 grams of plant-based protein and 3 grams of gut-friendly fiber – plus nearly 300 milligrams of potassium, close to a small banana."They're also lighter on total fat than most nuts while still supplying a balanced mix of mono- and polyunsaturated fats," Connell said.Pistachios are also rich in CoQ10 and vitamin B6 – both important for energy production – though Connell notes they may not be beneficial to everyone.YOU CAN EAT BREAD AND STAY FIT: HERE ARE 9 HIGH-FIBER OPTIONS FROM A HEALTH COACH"We often recommend pistachios when a person's biology shows signs of low energy production – with the caveat that they're moderately high in oxalates and don't suit everyone," she said."If you're sensitive to FODMAPs or oxalates, portion size and individual tolerance still matter."CLICK HERE TO SIGN UP FOR OUR LIFESTYLE NEWSLETTERFor consumers looking to maximize the health benefits of pistachios, Connell suggested going for real pistachios "in smarter vehicles."These include dark chocolate with chopped pistachios, homemade pistachio butter on toast and pistachio energy bites made from dates and oats, Connell said.The dietitian also suggested trying out a pistachio-matcha latte with pistachio paste or pistachios on Greek yogurt. If pistachios disrupt your digestion, Connell said that almonds, walnuts and sunflower seeds work just as well.If you're trying to lose weight, Connell noted that pistachios offer built-in portion control, thanks to their shells.MORE FROM FOX NEWS LIFESTYLE"Cracking shells slows you down and encourages mindful eating," she said, adding that they're also packed with antioxidants lutein and zeaxanthin, which support eye health.If you think you're getting all these nutritional benefits through pistachio syrups or Dubai chocolate, you'd be mistaken."Added sugars quickly outweigh benefits and strip away the very things you want from the nut," Connell said. "For the biggest payoff, choose plain or lightly roasted pistachios. Want more flavor? Roast at home with chili powder, garlic powder or paprika instead of adding sugar."