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Breast milk, sometimes referred to as "liquid gold," can be a life force for newborn babies. Many studies have shown that infants who breastfeed have a decreased risk for respiratory infections, acute ear infections, diarrhea, SIDS, and even leukemia and enjoy long-term benefits compared to formula-fed babies.

But is all breast milk created equal? After all, the nutrients in a mother's milk are highly dependent on her own nutrition. Breastfeeding moms are advised not to drink booze close to feeding, for example, as the alcohol can pass straight to the milk and thus to the baby.

A new study from Purdue University, published in PLOS One, set out to look into how the nutritional content of breast milk varies across regions by comparing samples from three countries: the United States, China, and Mexico.

Specifically, researchers¬†measured levels of health-promoting compounds known as carotenoids‚ÄĒplant pigments that are thought to play key¬†roles in human development and are key sources of vitamin A. Both beta-carotine and lutein are types of carotenoids.

For one year, researchers had¬†285 mothers¬†answer weekly questionnaires about feeding and dietary nutrition. At various intervals‚ÄĒtwo weeks, four weeks, 13 weeks, and 26 weeks after giving birth‚ÄĒbreast milk samples were collected from 60 women (20 samples from each region) to be analyzed in a lab.

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Researchers found that "mean amount of total carotenoids in American women's breast milk two weeks after giving birth was about 40 percent lower than levels in Chinese women's milk and about 25 percent lower than levels in Mexican women's milk," according to a press release of the results. The reason? Poor nutrition.

"Fruit and vegetable consumption appears to be pretty low across the nation," said Mario Ferruzzi, professor of food science and nutrition and author of the study. "In general, we [Americans] are just not consuming the recommended amounts." (Note that the study did not indicate how the breast milk from the three countries compared when looking at other nutrients.)

Since¬†carotenoids are plant pigments, the best way to consume them is by eating a lot of leafy greens, fruit, and vegetables. For example, breast milk from China was high in lutein‚ÄĒa carotenoid key in eye health‚ÄĒwhich researchers believe comes from a diet high in green vegetables.

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Breast milk from Mexico was high in the carotenoid¬†ő≤-cryptoxanthin, which they believe comes from consuming oranges and papaya. The U.S. and Mexico both ranked¬†high in¬†lycopene, which comes from tomatoes.

While eating the right foods is important, it's equally important to have access to the right foods, indicating socioeconomic factors could also be at play.

According to the USDA, 23.5 million people in the U.S. currently live in a "food desert," defined as an urban area or small town in which people do not have access to affordable fresh fruits and vegetables. Instead, their only option is processed or fast food.

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Indeed, for many American, access to affordable, nutritious food is out of reach. (Hey, we all saw Gwyneth fail the food-stamp challenge, further proving that buying fresh fruit and veggies on a $29 / week budget is next to impossible.)

But before we blast U.S. moms, Ferruzzi told Fusion that when comparing carotenoid levels, "It is not that one is better than the other, they just differ," with China leading the way in mean amount of total carotenoids, but not in every individual carotenoid.

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If anything, he says, this study advances our understanding of the composition of breast milk in different regions and "by extension the levels that infants will see in their diets."

Thus, he recommends, "Nursing women should eat fruits and vegetables as recommended in dietary guidelines. As long as your baby is happy with it, don't exclude bright orange or yellow produce and leafy vegetables from your diet."

The research on carotenoids is part of a larger study, The Global Exploration of Human Milk Study, which looks at dietary diversity in infants from the U.S., Mexico, and China. It was funded by Mead Johnson Pediatric Nutrition Institute and the U.S. Department of Agriculture National Needs Fellowship.

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Taryn Hillin is Fusion's love and sex writer, with a large focus on the science of relationships. She also loves dogs, Bourbon barrel-aged beers and popcorn ‚ÄĒ not necessarily in that order.