Few topics cause as much contention among those seeking a healthy diet as milk. Some promote it for its calcium and protein, while others claim that it is unhealthy or even unnatural for mammals to consume milk after weaning. Others believe that it is perfectly healthy for humans to use milk from other animals as a food source, as long as it is raw and unpasteurized, since pasteurization damages milk enzymes and proteins.

My opinion on milk is a bit more moderate. Milk is a perfect food for babies; it contains everything they need to thrive. It naturally provides protein, fat and sugar, all of which are necessary for the growth of muscle, bone and brain tissue, and also helps the baby to develop immunity.

The milk debate stems in large part from the fact that many adults can’t digest the sugar portion of this perfect food. The sugar in milk, known as lactose, is more complex than the glucose that our bodies use every day to run all of its processes. Glucose is a simple sugar that can be easily absorbed in the small intestine, but lactose requires enzymes to break it down before it can be absorbed.

The enzyme that breaks down lactose is called lactase. Babies are generally equipped with enough lactase enzyme to effectively break down sugars so they can be effectively absorbed. But lactase production declines as babies become children and adults. Depending on the amount of lactase available, different people can tolerate different amounts of lactose.

For those who lack enough lactase to break down the lactose they consume, malabsorption of milk sugar can cause significant health problems. Results can include gas and bloating, diarrhea or constipation, congestion or sinusitis, fatigue, and acne.

Children who tolerate dairy poorly often show excess mucus and recurrent ear infections. When the infections clear up, parents may believe that the child is “out of” their symptoms. In reality, intolerance can manifest itself in different ways as the child grows older. Adults more often show symptoms of digestive upset or skin problems.

Although dairy products can cause problems for some, they are a very common item in the food supply. Several agencies promote it as essential for protein and calcium to build strong bones. So what if you can’t tolerate dairy?

Indeed, calcium is necessary for good health, but fortunately milk is not the only dietary source of calcium. In fact, controlled studies have shown that neither milk nor calcium supplements reduce the risk of osteoporosis. Additionally, the countries with the lowest dairy consumption also have the lowest hip fracture rates.

If you can’t digest lactose effectively, there’s no danger in avoiding dairy products. A balanced diet that includes calcium-rich plant foods, such as leafy green vegetables, nuts, and legumes, can provide calcium and other important nutrients without the negative effects of milk.