“It’s complicated for adults, but it’s even more complicated for kids, and we have even less data,” Willett says. The calcium needs of kids are trickier to figure out. They’re growing, so they’ll naturally need more. But the role dairy should play in meeting their calcium needs isn’t clear. There is good evidence that kids who drink cow’s milk grow taller than those who don’t.
It’s not known exactly how milk accelerates growth. But the study authors say cows are often pregnant when they’re milked, which increases hormones like estrogen and progesterone. Cows have also been bred to produce more of another hormone, called insulin-like growth factor, which increases milk production, but those hormones may also promote growth in people.
There’s also some worry that hormones in milk may lead to the cancer later in life, but the evidence for that is mostly circumstantial. Kids need calcium for building strong bones, Willett says, but studies don’t show that adding a lot more dairy makes a difference.
One study, for example, randomly assigned 240 kids, ages 8 to 15, who weren’t getting enough calcium in their diets, to a meal plan with three added daily servings of dairy, or to continue on their normal diets. After 18 months, the study found no difference in bone density between the kids who had more dairy and the ones who didn’t.
Willett also notes that while the U.S. recommends that kids ages 4 to 8 get 1,000 milligrams of calcium in their diets, the U.K. recommends about half that much, just 450 to 550 milligrams a day. That doesn’t have to come from milk, he says. Other foods like kale, broccoli, tofu, nuts, and beans all count toward the goal. One important point, he says, is if dairy is off the table at your house, make sure your kids are getting vitamin D, though a dietary supplement.
Jean Welsh, PhD, who researches nutrition as an associate professor of pediatrics at Emory University, praised the reviewers for raising important questions about dairy. But she urged caution when it comes to taking dairy off the table for kids.
“What always makes me nervous when we talk about these key features of our diets is if we promote a change, what’s going to replace it?” says Welsh, who was not involved in the review.
“The study authors say that if you have a good-quality diet, you don’t need milk. Well, yeah,” Welsh says. “It’s not like we’re eating well.”
On average, many kids probably don’t get enough broccoli, kale, or other sources of calcium in their diets to meet all their needs, she says.
Milk is better than sugar-sweetened beverages, she says, especially for kids.
Welsh recently tested several brands of conventional and organic milk for pesticides, antibiotics, and hormones. While pesticides and antibiotics were sometimes found in the conventionally farmed milk samples, none were found in the organic milk samples. Hormone levels were also higher in the conventionally farmed samples, compared to the organic samples.
She says that if organic milk is too pricey, parents shouldn’t worry. Milk is still good for kids. Especially if they’re picky eaters.
“While there are advantages to drinking organic milk in that it’s free of chemicals often used in milk production, we do not have evidence that this makes a difference in children’s health,” Welsh says. “What we do know is that milk, organic or not, is a readily available source of nutrients important in the diets of children.”
"Ni ngumu kwa watu wazima, lakini ni ngumu zaidi kwa watoto, na tuna data kidogo zaidi", Willett anasema. Mahitaji ya kalsiamu ya watoto ni magumu zaidi kugundua. Wao ni kukua, hivyo wao asili haja zaidi. Lakini jukumu la maziwa linapaswa kucheza katika kukidhi mahitaji yao ya kalsiamu si wazi. Kuna uthibitisho mzuri kwamba watoto wanaokunywa maziwa ya ng'ombe hukua kwa urefu kuliko wale ambao hawainywi. Haijulikani hasa jinsi maziwa yanavyoongeza kasi ya ukuzi. Lakini waandishi wa utafiti wanasema ng'ombe mara nyingi huwa na mimba wakati wanapopikwa, ambayo huongeza homoni kama vile estrogen na progesterone. Kwa mfano, ng'ombe huzaana kwa ajili ya uzalishaji wa homoni nyingine inayoitwa insulin-like growth factor, ambayo huongeza uzalishaji wa maziwa, lakini pia huzaana kwa ajili ya uzalishaji wa homoni nyingine inayoitwa insulin-like growth factor. Pia kuna wasiwasi kwamba homoni katika maziwa inaweza kusababisha kansa baadaye katika maisha, lakini ushahidi kwa ajili ya kwamba ni zaidi ya kiashiria. Watoto wanahitaji kalsiamu ili kujenga mifupa yenye nguvu, Willett anasema, lakini uchunguzi haionyeshi kwamba kuongeza maziwa mengi hufanya tofauti. Katika utafiti mmoja, watoto 240 wenye umri wa miaka 8 hadi 15 ambao hawakuwa wakipata kalsiamu ya kutosha katika chakula chao walipewa mpango wa chakula na vipimo vitatu vya kila siku vya maziwa au kuendelea na chakula chao cha kawaida. Baada ya miezi 18, utafiti huo haukuona tofauti yoyote katika wiani wa mifupa kati ya watoto waliokula maziwa zaidi na wale ambao hawakula. "Wikipedia inasema kwamba ""Wakati Marekani inapendekeza kwamba watoto wenye umri wa miaka 4 hadi 8 kupata 1,000 mg ya kalsiamu katika mlo wao, Uingereza inapendekeza nusu ya kiasi hicho, 450 hadi 550 mg kwa siku.""" Hiyo haipaswi kuja kutoka maziwa, anasema. Vyakula vingine kama vile kale, broccoli, tofu, karanga, na maharagwe vyote huhesabiwa kuelekea lengo hilo. "Kama bidhaa za maziwa hazipatikani kwenye meza yako, hakikisha watoto wako wanapata vitamini D, ingawa ni kiboreshaji cha lishe. """ Jean Welsh, PhD, ambaye anafanya utafiti wa lishe kama profesa msaidizi wa pediatrics katika Chuo Kikuu cha Emory, aliwapongeza wahakiki kwa kuinua maswali muhimu kuhusu maziwa. Lakini alitoa wito wa tahadhari linapokuja suala la kuondoa maziwa kwenye meza kwa watoto. "Kile kinachonifanya niwe na wasiwasi wakati tunapozungumza juu ya sifa hizi muhimu za lishe yetu ni ikiwa tunakuza mabadiliko, ni nini kitakachobadilisha?"" anasema Welsh, ambaye hakuhusika katika ukaguzi huo. <unk>Waandishi wa utafiti wanasema kwamba ikiwa una lishe yenye ubora mzuri, huhitaji maziwa. Naam, ndivyo Welsh anavyosema. "Si kama sisi ni kula vizuri. ""Kwa wastani, watoto wengi pengine si kupata kutosha broccoli, kale, au vyanzo vingine vya kalsiamu katika mlo wao ili kukidhi mahitaji yao yote, anasema." "Kama vile tunavyosema, ""maziwa ni bora kuliko vinywaji vyenye sukari,"" hasa kwa watoto." Hivi majuzi, Welsh alichunguza maziwa kadhaa ya kawaida na ya kikaboni ili kuona kama yalikuwa na dawa za kuua wadudu, viuavijasumu, na homoni. Ingawa dawa za kuua wadudu na viuavijasumu nyakati nyingine zilipatikana katika sampuli za maziwa yaliyotengenezwa kwa njia ya kawaida, hakuna yoyote iliyopatikana katika sampuli za maziwa ya kikaboni. Viwango vya homoni pia vilikuwa vya juu zaidi katika sampuli za kilimo cha kawaida, ikilinganishwa na sampuli za kikaboni. Anasema kwamba ikiwa maziwa ya kikaboni ni ghali sana, wazazi hawapaswi kuwa na wasiwasi. Maziwa bado ni mazuri kwa watoto. Hasa ikiwa wao ni wenye kula kwa bidii. "Wakati kuna faida ya kunywa maziwa ya kikaboni kwa kuwa haina kemikali zinazotumiwa mara nyingi katika uzalishaji wa maziwa, hatuna ushahidi kwamba hii inafanya tofauti katika afya ya watoto, "Welsh anasema. "Kile tunachojua ni kwamba maziwa, ya kikaboni au la, ni chanzo cha virutubisho muhimu katika mlo wa watoto."""