Is Milk a Good Source of Calcium? Milk Myths Demystified

By November 10, 2013Food, Nutrition
milk calcium

There is no arguing that milk is a good source of certain nutrients.  The main nutrient milk contains is fat, since it is meant to provide lots of energy for a growing mammal.  But what about calcium? On the one hand, we’ve been bombarded with government health messages telling us to drink milk because it is a good source of calcium for growing bones.  On the other hand, it is weird that humans are the only animals who drink mmilk after infancy, and also that milk-loving Western countries have so much osteoporosis.  Vegan advocates will quickly tell you that milk depletes calcium from the bones.

So, who is right?  Is milk a good or bad source of calcium?

Here, we will take a lot at the milk argument from a health point of view (we aren’t going to get into the moral aspects of drinking milk here) to see what science says about milk being a good or bad source of calcium.

 

The Pro Milk Argument: “Milk is a good source of calcium and other nutrients”

As far as calcium content goes, milk and other dairy products are one of the best natural sources you will find. A single glass of milk has about 300 mg of calcium.  Because of poor bioavailability, it would take about 8 cups of spinach to get the equivalent amount of calcium. Only certain greens like Swiss chard come close to milk (see the best vegan sources of calcium here)

Along with calcium, milk is also a good source of potassium, phosphorus, zinc, selenium, vitamin B12, and Riboflavin.

For all the healthy nutrients in milk, there are also some major health risks associated with drinking it. Firstly, milk is loaded with saturated fat (a single glass gives you 15% of the DV for saturated fats!). The high amounts of saturated fat in milk could contribute to heart disease (the number one cause of death in the US!). Note that there are healthy types of saturated fat, but milk is not one of them.

Milk could be causing cancers. According to the Harvard School of Public Health, various studies have linked milk consumption to:

  • Ovarian cancer
  • Prostate cancer

There is also the issue of lactose intolerance, a condition which reportedly affects about 10% of the American population (much higher in African, Mexican, and Asian Americans).   As one author at the New York Times put it, “Although treating heartburn is a business worth more than $10 billion a year, the solution may be as simple as laying off dairy.”

 

Anti-Milk Arguments

Argument 1: “Milk Depletes Calcium from Your Bones”

Throughout numerous pro-vegan websites, you will read:

Milk pulls more calcium out of your bones than it gives you!

Before we go any further, I want to say right away that this is NOT true. However, like with most things related to nutrition, the answer isn’t so simple.  Studies show that some sources of dairy are indeed good sources of calcium whereas others may be bad for bones.

Consuming high amounts of protein has an acidifying effect and causes the body’s pH to rise. The body uses calcium to neutralize the acid, thus causing calcium to leach from the bones.  The released calcium is then excreted through urine.

For decades, this theory held true in the vegan community who claimed that drinking milk was bad for bone health.  More recent research has shown that the theory is NOT true.  As Jack Norris points out, this shouldn’t be surprising.  Protein is an important part of the bone matrix, so it wouldn’t make sense that protein would harm bones.

 

As Dr. Linda K. Massey writes in an article about calcium and bone health at The Journal of Nutrition,

When purified protein supplements are added to diets, calcium balance usually becomes more negative, suggesting that bone may be affected. However when increased protein is added as foods, particularly meat or dairy products, decreased calcium balance is not always seen, especially in young health people. This is due to other components of protein-containing foods that have also been shown to alter the urinary excretion of calcium and thus potentially calcium balance. These include phosphate, sulfate and potassium, as well as calcium.

She goes on to write:

Epidemiologic studies have added to our knowledge, but we do not yet know how much and what source of protein is protective of our bones.

Even if dairy does pull calcium out of our bones, there is little evidence showing that dairy pulls more calcium than it delivers. Contrarily, numerous studies show that milk consumption has a positive effect on bone health.

In a review of 57 significant studies about the effects of dairy on bone density which was published in The American Journal of Clinical Nutrition, the researchers found that:

  • 53% of the outcomes were not significant
  • 42% showed that milk/dairy has a favorable effect on bone health
  • 5% showed that milk/dairy has an unfavorable effect on bone health

When breaking down the results from the 12 “strong evidence” studies (meaning that the studies have over 3000 participants who were followed up for an average of over 5 years), the researchers found:

  • 50% of the outcomes were not significant
  • 42% showed that milk/dairy has a favorable effect on bone health
  • 8% showed that milk/dairy has an unfavorable effect on bone health

I know that many vegan advocates will claim that these studies are influenced by the dairy industry. But, no matter how disgusting or unnatural you may find dairy consumption to be, we can’t overlook the fact that most studies do show that dairy is beneficial to bone health. It is irresponsible of vegan advocates to ignore these studies and only cite the few which show dairy has unfavorable effects on bone health.

While milk does appear to be a good source of calcium, this doesn’t necessarily mean that dairy is always a good source.

Studies show that not all dairy products are the same. As the AJCN analysis points out, the way that dairy products are produced can significantly alter their nutritional value. For example, cottage cheese, which is made by acidic curdling, has ½ the calcium and potassium content of milk but 4x the protein and 8x the sodium. Along with protein, sodium is also guilty of removing calcium from the bones. Increasing sodium intake by 1 gram has been associated with the loss of 20 to 40mg of calcium. Thus, cottage cheese is a poor source of calcium compared to milk.

***It is worth noting that there are very few studies about the effects of dairy on the bone health of minority groups and men. Further, only two studies analyze the effects of different types of dairy.

 

Argument 2: “The West Has Higher Incidence of Osteoporosis”

The other main argument against dairy as a source of calcium is this: the milk-loving western world has much higher incidences of osteoporosis than the parts of the world where dairy is rarely consumed. To take an example from Harvard School of Public Health, the average calcium intake in India, Japan and Peru is as low as 300mg/day (compare to the 1000mg/day RDA in the US) – yet the incidence of bone fractures is much lower there.

While there is no disputing the fact that Westerners have higher rates of osteoporosis, this argument fails to take into consideration the many other factors which affect bone health. Westerners are much more at risk of bone-health problems due to numerous lifestyle factors:

  • Lack of exercise
  • High intake of sodium
  • High consumption of colas and coffee

One study published in the Journal of Bone and Mineral Research found that weight-bearing activity had a much greater effect on bone health than calcium intake did. Another study published in the Journal of Clinical Nutritionfound that calcium intake explained less than 0.7% of variations in bone density. Rather, factors like age, body weight, and menopause had a large impact on bone health.

Westerners also don’t eat as many fermented foods as in many Asian countries.  Fermented foods (like kimchi and natto) are good sources of vitamin K2.  Recent research has found that K2 is needed to help channel calcium to where it is needed in the body.

As Robert Heaney, MD, said in the Journal of the American College of Nutrition, “Osteoporosis is a complex, multifactorial disorder, and ensuring a high calcium intake is only one of several necessary preventive strategies.”

 

Argument 3: “Vegetables are a Superior Source of Calcium”

There is no doubt that vegans can meet all their calcium needs from plant products alone. Foods like kale and beans have high amounts of calcium. However, plants are not necessarily a “superior” source of calcium.

Many of the calcium-containing plant foods also are high in acids which inhibit calcium absorption. Thus, this reduces the bioavailability of the calcium in many vegetables. On the other hand though, dark, leafy vegetables are often high in vitamin K, which aids in calcium regulation and formation.

Unfortunately, it does seem as though vegans may not be getting adequate calcium in their diets. In one study published in the European Journal of Clinical Nutrition, it was found that vegans have a higher rate of fracture than vegetarians and meat eaters. While the study did consist of nearly 35,000 participants (of which over 1000 were vegan), this study obviously does not imply that all vegans are calcium deficient. Yet, it does indicate that vegans should be paying close attention to whether they are getting enough calcium in their diets.

 

It Shouldn’t Matter whether Milk is a Good Source of Calcium!

Due to all the hormones, antibiotics and other generally scary stuff that gets into milk products, avoiding milk seems like a wise health choice. Of course, there are all those organic, free-range milk products too but, for many, it is simpler just to stop consuming dairy than try to ensure you are only getting the organic variety.

The issue of hormones and etc. aside, the healthiness of milk shouldn’t have too much influence on your argument for going vegan. So what is milk does have some health benefits? I’m sure that cannibalism would provide some good nutrients too – but no one uses that as an argument for eating people!

I personally hate the “meat is healthy” argument against veganism. Yes, humans are naturally omnivores and designed to eat meat. However, humans do a LOT of things which are far from natural – like wearing glasses, driving cars, and using air conditioning.   Because of the “unnaturalness” of our modern lives, we can now live healthily as pure vegans thanks to innovations in horticulture, importing foods, and supplements.

But please vegans: Stop promoting veganism based on the idea that “milk is unhealthy” or “bad for bones.” It will only isolate more people. Instead, try pouring your anti-vegan adversary a glass of soymilk!

 

 

About Diane Vukovic

Diane Vukovic is a vegan mom, health nut, and kitchen diva. When she's not deducing veggie nutritional facts, she's probably dancing crazily with her daughter or traveling somewhere in Europe.

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