Livestock is a significant contributor to global warming, with cattle alone contributing around 10% of global greenhouse gas emissions.

But we won’t get into that here. Instead, we’re going to dissect the longstanding notion that cow milk is an essential part of a healthy diet for humans.

It was 1984 when the National Dairy Board popularized the slogan “Milk: It Does a Body Good”. The commercials featured people transforming into healthier and fitter versions of themselves after drinking milk. They certainly succeeded in retaining yours truly as a milk devotee for much of his life.

It would take me decades to realize reality doesn’t always live up to the hype.

If you’ve read some of my other posts, you’d be forgiven for thinking I’d be singing the praises of milk, a fully natural, whole food. And indeed, dairy, when consumed appropriately, has a lot going for it. But “natural” doesn’t automatically mean “good for you”. Mushrooms and berries in the wild are natural, but eat the wrong one and you’ll get sick or die.

Also, what’s nourishing to one person may be poison to another. Think peanut or other food allergies.

What those milk commercials conveniently left out is that around 70% of the adult human population has some degree of lactose malabsorption, meaning they lose the ability to digest lactose, the natural sugar found in milk. Among Asians, that number is closer to 90%.

Lactose malabsorption is lowest in Northern European populations, where they have a long history of dairy consumption and have adapted to it, but even there the prevalence is close to 10%. If you consider the U.S. only, it’s at least a third of the population, still a significant number.

The evidence shows that lactose malabsorption is actually the default state of the human digestive system rather than a disorder. As infants, we all have the ability to digest lactose, allowing us to nurse. As we go through childhood, we start to lose that ability as lactase production tapers off in our bodies. This is true of all mammals, not just humans.

The few who are able to digest lactose today as adults are directly benefitting from a genetic mutation that first appeared in their ancestors thousands of years ago.

So what? I like milk.

Despite all that, many of us who don’t carry the special gene continue to consume milk into adulthood, unaware of the damage it may be doing to us. When the body is unable to break down lactose, it usually leads to digestive symptoms like bloating, gas, and diarrhea. A person who experiences these symptoms after consuming dairy is termed lactose intolerant. The vast majority of people with lactose malabsorption are also lactose intolerant.

If you are sure you never experience those symptoms after consuming dairy, you can probably stop reading. But consider that you may be lactose intolerant and not know it. Maybe you have somewhat loose stools but attribute it to the fiber in your diet or the stress you’ve been experiencing lately. Or maybe your digestive system has behaved this way for so long that you just consider it normal rather than suspecting an issue with dairy as the cause.

You will not wake up one day suddenly lactose intolerant. Instead, it creeps in over time so may go unnoticed. It may also be mistaken for other GI disorders.

But even mild diarrhea is not normal. Stools should be solid, with a definite shape and form. Anything loose or watery may be fine if it’s an occasional occurrence in a healthy adult, but chronic diarrhea is a major problem with both short-term and long-term side effects.

Short term effects include:

• The fluid loss from dehydration can lead to dry mouth, dizziness, headaches, and fatigue.
• The loss of electrolytes can cause cramping and affect heart rhythm, blood pressure, and mental clarity.

Long-term diarrhea can lead to kidney problems, as well as malnutrition by preventing the body from absorbing enough nutrients from food. Malnutrition can then lead to more concrete issues over time:

• Anemia from poor absorption of iron and folate, with symptoms like weakness and exhaustion, pale skin, and cold hands and feet.
• Loss of calcium and vitamin D, leading to bone weakness and fractures.
• Loss of other vitamins, leading to vision and immune issues, hair loss, and nerve issues like tingling.

Then there are the quality-of-life issues, like social withdrawal and anxiety around eating or leaving home. Left untreated, it can even lead to depression.

Do you consume dairy and experience subtle or clear digestive issues, perhaps alongside some of the other issues above? Then you may be lactose intolerant–read on to learn how to get tested.

Am I lactose intolerant?

On global statistics alone, the average adult is lactose intolerant. Symptoms can begin at any age after weaning, but for the majority it happens between the ages of 10 and 30. Again, it’s a gradual process–for some it may happen in their 50s, while for others it may never happen, granting them a lifelong tolerance to milk.

So how do you know if you’re affected? Fortunately, there are multiple ways to find out. The most obvious is to drink a glass of milk on an empty stomach and observe your symptoms for the next 30 minutes to 2 hours. Here is a test procedure with details. (Yes, this is from the company Lactaid, which has a vested interest in selling you their products; however, the test itself is straightforward and does not rely on proprietary methods.)

If you notice digestive symptoms after drinking milk that you normally don’t have, then you’re probably lactose intolerant. Those symptoms can include bloating, cramps, gas, diarrhea, nausea, and stomach rumbling. The extent and severity of your symptoms indicate your level of intolerance.

A more common and accurate (but still easy) way to test yourself is to take a hydrogen breath test. Test kits like this one can be ordered online for at-home testing, or you can visit a doctor to get tested. There are also blood and stool tests available.

Most people can expect to become lactose intolerant by age 30. For the rest, it’ll happen later or not at all.

Since lactose intolerance can strike at any age, it makes sense to get tested every few years, or to at least be aware of the symptoms so you can take action as needed.

You can still have dairy

So you’ve discovered you’re lactose intolerant. Fear not, for all is not lost. Lactose intolerant folks can and do eat dairy products regularly. Everyone has a level of lactose they can tolerate, and not all foods are created equal, even with equivalent lactose amounts. The trick is to know what you can eat and your personal limit, both of which require experimentation and can change over time.

Drinking an undiluted glass of milk straight up would give you a high dose of lactose quickly. But milk is only one form of dairy, and other forms can be easier to digest. For its part, the USDA in 2011 changed “milk” to “dairy” in its food guide recommendations. Here are some common dairy products and their approximate lactose amounts:

Product	Serving size	Lactose (grams)
Condensed milk	1 cup	30
Evaporated milk	1 cup	24
Milk	1 cup	12
Yogurt (American or Australian)	1 cup	10
Yogurt (Greek or Icelandic)	1 cup	6
Ice cream	1/2 cup	6
Sour cream	1/2 cup	4
Cottage cheese	1/2 cup	3
Cream cheese	2 Tbsp	2
Cheddar cheese	1 oz	0.5
Butter	1 Tbsp	0.1

Yogurt is an interesting case because the bacteria used in its production helps with lactose digestion. Despite the relatively high lactose content, almost all people can digest moderate amounts of it just fine, making it a great option for lactose-intolerant individuals. Icelandic (skyr) and Greek yogurts are the safest bets due to their lower lactose levels. Look for yogurts that list active cultures in the ingredients–these are the probiotics that help with lactose digestion.

Despite the relatively high lactose content, most people can digest moderate amounts of yogurt just fine.

Cheese can be another good option provided you choose one with a low lactose content. Some hard cheeses contain virtually no lactose as it’s removed or converted during the production process. You can tell by reading the nutrition label–since lactose is a sugar, look for Total Sugars to be 0, indicating a “lactose-free” product (in quotes because there could still be traces of lactose depending on how the number is calculated).

Products like milk, yogurt, and ice cream also come in lactose-free varieties. Or you could take a lactase supplement with regular versions of these products as needed.

If you are particularly sensitive to lactose, note that some traditionally non-dairy foods actually contain dairy–for example, whey is used in some granola bars, and caseinate is found in some processed meats, pastas, and baked goods. When in doubt, read the labels.

Even in sensitive individuals, the body has some ability to adapt to lactose through regular dairy consumption. That’s why it may benefit you to determine how much dairy you can tolerate and make it a point to consume it regularly to maintain–and possibly somewhat enhance–your tolerance level over time.

Plant-based milks: Better than ever

If you grew up eating oatmeal or cereal with milk in the mornings, you might still have a taste for those foods as an adult. But what if you can’t drink milk anymore?

One option, as mentioned, is to buy lactose-free milk or take a lactase supplement with regular milk. But this may not work for everyone, namely vegans, or those whose bodies may be sensitive to even traces of lactose. Others may not like the taste of milk or the idea of drinking a modified version. Then there is the environmental impact of raising cows.

That’s where plant-based milks come in. Examples include milks made of soy, peas, coconut, oats, or various nuts, like cashews or almonds. In fact, there are now more varieties of plant-based milk than regular milk on many American grocery store shelves.

While taste and texture vary across milk source and brand, I’ve found most varieties to be worthy substitutes to dairy in a bowl of cereal. As a result, and in line with the general recommendation to eat a variety of food types, I try to mix things up while prioritizing objective quality over taste–healthier plant milks usually have fewer ingredients and no added sugars.

What about essential nutrients?

If your body can tolerate it, dairy is fine as part of a balanced diet. As with all foods, moderation is key.

If you’re avoiding milk, and since the USDA still recommends consuming dairy for optimal health, you might be concerned about your calcium and vitamin D intake. But this is not a problem because milk is not the only source of these nutrients.

Here are some good ways to get the nutrients milk would normally provide:

• You can get vitamin D from foods like fatty fish, supplements (which is where milk gets it), or by spending time in the sun, which is good to do anyway.
• For calcium, yogurt and hard cheeses are good sources. Most people who are lactose-intolerant can tolerate yogurt, as mentioned earlier, and some can tolerate cheese in smaller amounts.
• Good non-dairy sources of calcium include white beans, collard greens, chia seeds, and certain seafoods, among others. You can also take supplements.
• Plant-based milks are often fortified with calcium and vitamin D. Check the labels.

If you don’t mind lactose-free milk, it has about as much calcium and vitamin D as regular milk.

I do think the health concerns of abstaining from dairy are overplayed. Many East Asian communities have some of the highest life expectancies and lowest rates of chronic disease anywhere in the world, yet their diets hardly contain any dairy.

Granted, some of that may be attributable to genetics and lifestyle, but it also shows it’s possible to be healthy without dairy as long as you’re getting those nutrients elsewhere. In fact, ever since I stopped drinking milk (I do eat yogurt), I have more energy, think more clearly, and my general health has vastly improved. Realizing that milk was causing my issues was a clear game changer for me.

Conclusion

Milk is not always the superfood we’ve been led to believe.

Despite historically loud pushes from the industry and regulators that milk is a dietary essential, the fact is that most adults worldwide have trouble digesting the lactose it contains. Asian cultures in particular are disproportionately affected and many have a history of low or no dairy cuisines. Despite this, they enjoy high life expectancies by getting their nutrients from other food sources.

A significant portion of the global populace may be unaware of their lactose intolerance and thus continue consuming dairy at their peril. But it need not be that way. Getting tested is easy, can be done at home, and would provide peace of mind for anyone who experiences excessive gas, bloating, or more severe digestive issues and wonders if dairy might be the cause.

Being lactose intolerant doesn’t mean abandoning all dairy. On the contrary, consuming dairy in small amounts up to your personal tolerance level can help maintain and possibly even enhance that tolerance. Low-lactose options like Greek yogurt can be enjoyed in moderation by most people and provide the nutritional positives of dairy while avoiding the negative effects.

While a glass of undiluted milk would supply a taxing dose of lactose for many people, the increasing number of lactose-free and dairy-free alternatives allows us to continue enjoying our morning cereal, oatmeal, and all the other ways in which we have grown accustomed to milk in our daily lives.