Making Sense of Milk by Frankie Wood-Black the Array of Milk Options on Store Shelves Can Be Overwhelming
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February/March 2019 Making Sense What’s Clean, Green of Milk Sunless Tanner? Chemistry www.acs.org/chemmatters Page 5 Page 8 Page 15 Production Team Managing Editor, Christine Suh Administrative Editor, Emily Abbott Graphic Designer, Kelsey Casselbury Editorial Assistant, Lisette Gallegos Copy Editor, Therese Geraghty Connecting Chemistry and Art Senior Web Editor, Lorinda Bullock Web Associates, Cornithia Harris, Fred Colon Content Reviewers, Kim Duncan, Blake Aronson, James Kessler Technical Reviewers, Seth Brown, David Voss Spanish Translator, Luz D. Burgos Teacher’s Guide Team Team Leader, William Bleam Editors, Pamela Diaz, Steve Long, Barbara Sitzman Reading Consultant, Susan Cooper Education Division Executive Vice President, LaTrease E. 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Here’s a primer on how tanning products work. 11 The Periodic Table Turns 150 By David Warmflash That iconic chart of elements in Clean, Green Chemistry your classroom turns 150 this year! Celebrate with a look at its past and p. 15 a peek into its intriguing future. Spanish translation available online! 15 Clean, Green Chemistry By XiaoZhi Lim High school students from around the U.S. try their hand at green chemistry, an approach that prioritizes the planet and people’s health. ON THE COVER: THINKSTOCK Get More on the Web! Receive a complimentary subscription to ChemMatters when you become a member of www.acs.org/chemmatters Find Spanish-translated articles, Teacher’s Guides, and videos. Learn how to subscribe to the digital version of ChemMatters on our website or by calling 1-800-333-9511. bit.ly/AACTChemMatters ChemMatters | www.acs.org/chemmatters 3 OPEN FOR DISCUSSION Should We Eat Like Our Stone-Age Ancestors? By Michael Tinnesand n 2014, as word of the paleo diet allows us to break down lactose (Fig. 1), would spread, one columnist predicted its shut off—and toddlers would lose the ability to quick demise. Many dieticians said digest milk. Ithere was no evidence that the life- But as humans began domesticating cows style trend was beneficial. But today, and goats, milk from these animals became proponents continue to promote it. a source of nutrition. Adults still had a hard time digesting the animal milk, but turning Paleo’s adherents suggest that we it into cheese reduced the lactose content, should eat like early humans did which made it easier to digest. Milk became an easier-to-drink option when a random DNA about 3.3 million to 10,000 years ago. mutation in some people allowed the lactase This was the era of hunter-gatherers, gene to stay active into adulthood. before the development of agriculture. Stone Age diets consisted of wild fish, THE MILK ADVANTAGE game, fruits, nuts, and roots. It did not Figure 1. Enzymes are biological catalysts that speed up reactions. Lactase, for example, enables the breakdown of include animal milk or dairy products, Incorporating animal milk in a person’s diet lactose into simple sugars. legumes, modern grains, or any pro- turned out to be an advantage. Genetics cessed foods. researchers have reported that between 5,000 and 10,000 years ago, lactose-tolerant people But over the years, our diets have changed in some parts of the world, including North- profoundly due to advances in agriculture and We’ve bred animals to be fast growing and ern Europe, reproduced at a higher rate than technology. Paleo proponents argue that our provide large amounts meat. We’ve favored lactose-intolerant individuals. Two-thirds of bodies are still similar to the bodies of our the biggest, hardiest and plumpest varieties of the global population are still lactose intolerant ancestors and therefore out of sync with the fruits and vegetables, so they bear little resem- as adults. But the fact that one-third of us can modern diet. So, should we eat like hunter- blance to their plant predecessors. Tomatoes drink milk without running to the bathroom gatherers? in the Stone Age, for example, were the size of afterwards shows how well we can adapt—and berries. benefit from—dietary changes. REALITY CHECK At the same time, humans’ bodies have also As the saying goes: You can’t go home again— First, let’s consider if it’s even possible to find changed. The ability to digest milk sugar, and perhaps that is true with our diets as well. food that resembles meats and produce from called lactose, is a prime example. In Paleolith- If we could time-travel and sit down for dinner the Paleolithic era. Nearly all the foods we ic times, infants were nourished by their moth- with a family of cave-dwellers, it would be buy today have been significantly modified by er’s milk. But after about two years of age, the an interesting meal. But whether it would be selective breeding over the past 10,000 years. gene that produces the enzyme lactase, which healthier is open for discussion. 4 ChemMatters | FEBRUARY/MARCH 2019 ILLUSTRATION: THINKSTOCK Making Sense Looking for an alternative to cow’s milk? Here’s what you need to know. of Milk By Frankie Wood-Black o to the dairy section of any grocery store, and you’ll find a variety of milks made from soy, nuts, or rice in addition to good ol’ cow’s milk. Plant-based beverages aren’t necessarily new (almond milk has been around for centuries), but their production has boomed in recent years. G If you’re looking to replace cow’s milk, how do you know what to choose? To understand the difference be- Given the differences in how milks tween plant milk and animal milk, are produced, let’s see how the let’s first turn to biology. Animal nutritional profiles compare. milk is a complex fluid produced by the mammary glands of female mammals to feed their young. In What’s in dairy milk some ways, the nutritional purpose You probably already know that of animal milk resembles that cow’s milk is a good source of of nuts and seeds (technically, calcium. But it’s also a source what we usually call nuts, such as of many vitamins, minerals, and almonds and walnuts, are seeds). lipids—or fats. Additionally, it Seeds contain nutrients that em- contains sugars, hormones and bryonic plants use to develop into proteins, such as casein, immuno- seedlings.