This popular online theory says it can be dangerous to give babies solid foods before age six months. Is there anything to it?

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Baby Holding Toothbrush
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There are so many pressures and decisions you face on day one of becoming a parent: Breast or bottles? Cloth or disposable? Co-sleep or crib? It's enough to make anyone confused and overwhelmed (and feeling judged by someone, no matter what you choose).

Now there's another pressure to add to the list: Although most pediatricians recommend starting solids between 4-6 months based on your baby's readiness, a theory has spread on the internet that babies have "Virgin Guts" until six months of age--and that introducing solids before that time could lead to serious health problems.

The theory, popularized by a couple of widely-shared blog posts, states that until six months of age, babies have "open guts"--spaces between the cells in their small intestine that can allow large molecules to pass through, into the bloodstream. As the theory goes, if babies get only breast milk during the first six months, their guts remain "virgin". But introducing solids, they say, destroys this sterile environment and allows bacteria and toxins into the system, which can lead to allergies, metabolic syndrome, and chronic disease. Yikes! That's enough to make anyone pack up the pureed peas until later.

Problem is, the theory isn't actually supported by science, says Alice Callahan, PhD, author of The Science of Mom: A Research-Based Guide to Your Baby's First Year. Yes, she says, babies are born with guts that are permeable—but gut "closure" actually happens very early on, within the first few weeks of life.

(Formula feeders: You'll be happy to know that formula doesn't seem to affect this gut "closure" very much. According to Callahan, there's no difference in intestinal permeability between formula-fed and breastfed babies by one month and beyond.)

Not only is the Virgin Gut theory inaccurate, but it also creates unnecessary anxiety for parents, says Callahan. "It makes it seem like solid foods are dangerous for babies, that their GI tracts can't handle them," she says. "I worry this attitude makes it harder for parents to follow their babies' developmental cues for when they're ready to try solid foods, and it makes it harder for parents and babies to enjoy the process of gradually exploring solid foods."

The other concern is that it could mean parents are unnecessarily delaying solids. Though the Virgin Gut theory warns that starting solids before six months could lead to allergies, new guidelines from the National institute of Allergy and Infectious Diseases state that some babies should actually have exposure to peanut protein as early as four months to help prevent allergies. "For allergy prevention, or any question of infant health, it's best to follow evidence-based professional guidance," says Callahan.

Bottom line: Lose the anxiety. Pay attention to when your baby starts expressing interest in solids—and enjoy this natural part of development. "If they can sit up and take a bite from a spoon or handle soft finger foods, then you can let the fun begin," she says. "Babies develop at different rates and with different interests, and there's no reason to think that starting solids should happen at the same time for every baby. Follow your baby's lead, and have fun with the process!"

Sally Kuzemchak, MS, RD, is a registered dietitian, educator, and mom of two who blogs at Real Mom Nutrition. She is the author of The Snacktivist's Handbook: How to Change the Junk Food Snack Culture at School, in Sports, and at Camp—and Raise Healthier Snackers at Home. She also collaborated with Cooking Light on Dinnertime Survival Guide, a cookbook for busy families. You can follow her on Facebook, Twitter, Pinterest, and Instagram. In her spare time, she loads and unloads the dishwasher. Then loads it again.