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  • Over the last decade, milk has become a bit controversial.

  • Some people say it's a necessary and nutritious food, vital for healthy bones,

  • but others say it can cause cancer and lead to an early death.

  • So, who's right?

  • And why are we drinking it anyway?

  • [Intro music]

  • Milk is the basis of every mammal's diet after birth,

  • when our digestive systems are immature and small.

  • Basically, it's power food to kick-start our bodies and help us grow.

  • Milk is rich in fat, vitamins, minerals, and milk-sugar: lactose.

  • On top of that, for a while after birth, it also contains antibodies and proteins

  • that protect us from infections and regulate our immune system.

  • But it's a lot of effort for mothers to produce.

  • Eventually, humans stop drinking mother's milk

  • and transition to the diet of their parents.

  • This is how it's been for thousands of years.

  • Until about eleven thousand years ago,

  • when our ancestors settled down in the first agricultural communities.

  • Soon, they domesticated the first dairy animals:

  • goats, sheep, and cattle.

  • They found that dairy animals are able to eat useless and abundant stuff

  • and turn it into nutritious and tasty food.

  • This made a huge difference in terms of survival,

  • especially in hard times.

  • So groups that had milk available had an evolutionary advantage.

  • And through natural selection,

  • it changed the genes of communities who consumed a lot of it.

  • This adaptation has to do with a specialized enzyme: lactase.

  • Babies have a lot of it in their system,

  • so they can break down the milk-sugar lactose and digest milk easily.

  • But the older we grow, the fewer lactase enzymes our body produces.

  • Worldwide, about 65% of the population do not have the enzyme after infancy,

  • which means they are not able to digest more than about 150 milliliters each day.

  • This lactose intolerance is not spread evenly around the world, though.

  • In some East Asian communities, for example, it's up to 90%.

  • In Northern Europe and North America, the rates are the lowest overall.

  • There are probably a few reasons for this uneven distribution.

  • The trait was first introduced by random mutation,

  • which happened independently of each other in a few populations.

  • The fact that farming replaced hunting and gathering more and more

  • created natural-selection pressure.

  • People who were able to digest lactose had more foods at hand,

  • which was an advantage.

  • The migration of dairy farmers to the north then spread it further, which probably pushed back populations there that didn't have the trait.

  • Okay, but if milk has been a valuable part of our diet for thousands of years, why is it so controversial?

  • There are a number of claims regarding the negative and positive health effects of milk.

  • The negative ones cover a wide variety,

  • from brittle bones to cancer, and cardiovascular diseases to intolerance and allergies.

  • So, how do they hold up?

  • Some older studies found a connection between milk and a high risk of breast, colon, and prostate cancer

  • But meta analyses found no impact on your cancer risk.

  • On the contrary, the calcium in milk might even have a protective effect against colon cancer.

  • Although this could be calcium in general, it's not clear milk plays a role in this effect.

  • Only studies on prostate cancer showed an increased risk for people who consumed more than one and a quarter liters of milk a day.

  • But again, the association is inconsistent and other studies don't find any effects.

  • We discuss these studies in more detail in our sources document. All in all, the research seems to show that if you drink between

  • 100 to 250 milliliters of milk per day, cancer is not a concern.

  • Similarly, meta-analyses could not find any impact from milk or dairy products on

  • your risk of heart disease, stroke, or your total mortality.

  • Some studies even suggested that high blood pressure might be rarer in people who eat a lot of dairy,

  • although the evidence is not strong enough to claim this with confidence.

  • The case gets more complicated though when we look at bones.

  • A number of studies found neither positive nor negative effects for adults.

  • What most people worry most about though are harmful amounts of pesticides, antibiotics, or hormones.

  • There are hormones in milk, but only in very low concentrations.

  • For example to get the same amount of hormones as from the pill,

  • you'd need to drink about 5000 litres of milk,

  • and even if you did, most hormones would be destroyed by your digestive system

  • before they could affect you,

  • which is the reason why so much medication is coated to protect it from our digestion.

  • For pesticides and antibiotics,

  • there are regulations in most parts of the world that only allow completely harmless amounts.

  • Milk that surpasses these thresholds is not allowed to go on the shelf.

  • So there's nothing in particular to worry about.

  • Besides allergies and those suffering from lactose intolerances,

  • the best known negative effects of milk are probably acne and general discomfort after drinking milk or eating dairy products,

  • and here the effects are very real.

  • For example, skimmed milk has been found to statistically increase the rate of acne by 24%.

  • Allergies against milk products are especially prevalent among children, with one in 18 kids in Germany suffering from them.

  • In general, these allergies tend to get better or disappear as they grow older though.

  • Okay. Is milk healthy then?

  • Milk, no matter if it comes from mothers, cows, sheep, goats, or camels is a nutrient-dense food.

  • It contains all necessary macronutrients and many micronutrients.

  • Especially in regions where people struggle to get enough calories,

  • milk can contribute to a healthy life and lower child mortality.

  • For those living in the developed world, in general

  • milk is not harmful if you are not allergic or intolerant to it.

  • Especially for children, it's a good way to get large amounts of calcium

  • and for vegetarians, it's a good source of vitamin b12 and B vitamins in general.

  • This does not mean there are not other alternatives with the same effect. You do not need to drink milk to be healthy

  • Milk is also definitely not a substitute for water.

  • Milk is power food, and the additional calories from drinking a lot of it on a regular basis can contribute to being overweight.

  • Especially flavored milk or chocolate milk is more comparable to beverages like lemonade than a healthy snack, and there's another thing to consider.

  • Milk production has a significant impact on the global climate.

  • About 33 percent of cropland is used to feed grazing animals including dairy cattle

  • Even though the carbon footprint of dairy products has declined since 1990,

  • Dairy production is still responsible for 3 percent of all greenhouse gas emissions,

  • even more than all airplanes combined.

  • Milk is a huge industry and sadly, most of its production in factory farms causes incredible suffering.

  • Cows are impregnated over and over, separated from their young shortly after birth,

  • and slaughtered once their tortured bodies are not productive anymore.

  • We can't ignore that much of the milk we consume stems from an industry

  • that is basically torture and contributes to climate change.

  • What about plant-based milk?

  • In terms of protein levels and nutritional value, only soy milk can compare to cow milk.

  • The others need to be artificially enriched to reach similar levels of vitamins and calcium.

  • So they can be an alternative to milk.

  • And another option might be available soon.

  • Several startups have created non-animal milk

  • that is nutritionally identical to dairy milk,

  • for example, through fermentation by gene modified bacteria.

  • This lab-grown milk can even be turned into cheese,

  • something that plant based alternatives struggle with because they lack casein and whey protein,

  • the key ingredients that give dairy its taste and structure.

  • The environmental impact is a different story though.

  • Many milk alternatives use significantly less energy, land and less water to produce

  • so they have a much lower environmental impact than animal milk.

  • If you want to have the lowest possible negative impact on the planet, the best choice is whatever milk alternative is regional.

  • As with almost any topic milk is complicated.

  • It's not harmful for the majority of the population and it's crucial for many people around the world.

  • It's good, nutritious food, but also harmful to the planet and causes a lot of suffering.

  • We need to decide as a society how we want to deal with these facts.

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  • [Outro music]

Over the last decade, milk has become a bit controversial.

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B2 US milk dairy lactose cancer calcium healthy

Milk. White Poison or Healthy Drink?

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    祖祖 posted on 2020/03/02
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