Boning up on calcium
Calcium is vital to avoid bone-threatening diseases like osteoporosis – yet in countries where residents eat the highest amount of calcium and protein, they also have the highest number of hip fractures, a symptom of osteoporosis. Because the truth is, scientists are coming to the conclusion that there’s more to osteoporosis than just the amount of calcium we eat – overall lifestyle plays a large part, including physical activity levels and environmental factors. Just eating four to five servings of calcium-rich foods each day is no guarantee that you’ll avoid osteoporosis – but it’ll certainly be a step in the right direction.
Dairy industry propaganda tells us that “milk does a body good,” but that’s simply not true. Over two-thirds of the people in the world are lactose intolerant, making it difficult to digest milk. The cause is an insufficient amount of lactase, the enzyme that breaks down the sugars in milk. Undigested, the mucous-y lactose coats the lining of the colon, bacteria interact with it to cause gas, and the result is cramps, flatulence and diarrhea. All mammals are born with a sufficient amount of lactase, but in decreases as we get older – once we’re out of infancy, we’re not meant to be drinking milk any longer.
But while we don’t need to drink milk, we still need calcium. Almost all of the calcium in our bodies at any given time is stored in our bones and teeth, with about 1 percent in our bloodstream. And that’s the calcium that’s key to good health – it’s needed to send messages between nerves, especially those that contract our muscles. It’s also a vital component in the clotting of blood. Our kidneys filter most of our bodies’ calcium and return it to the bloodstream, but some of it is lost in our urine. We also lose some through sweat and bowel movements.
Our bones are constantly breaking down (don’t worry – they build back up!) replenishing calcium into our blood. Somewhere around the age of 30, our bones stop growing and reach maximum density. This is why calcium is most important when you’re young – the denser your bones are when they reach this stage of development, the less chance you’ll get osteoporosis when you’re older. That’s because after 45 our bones break down faster than they’re rebuilt – at this point we start to lose as much as 0.5 percent of our bone mass each year. So by the time we hit 65, bone loss can start to be a real problem. Women lose even more bone mass when they reach menopause, as they stop producing estrogen, the hormone that protects our bones.
We can’t increase the density of our bones once they stop growing, but we can slow the rate that calcium disappears from our bones by making sure that we eat calcium-rich foods. This applies whether you eat an omnivorous diet, an ovo-lacto diet or a completely vegan diet – there is no firm evidence that vegetarians have stronger bones than people who meat eat, or weaker bones. But some nutritionists believe that vegetarians may actually need less calcium to keep their bones strong.
How can that be? Well, protein from plant sources are metabolized by the body in different ways that animal proteins. Meat contains more sulfur-containing amino acids than plant proteins, which makes the blood more acidic. To neutralize the acid, your body needs more calcium – and what it doesn’t find in the bloodstream it pulls from our bones. That calcium then leaves your body in your urine, taking even more calcium from your kidneys along the way.
In addition, sodium takes a heavy toll on your body’s calcium supplies, and along with table salt, sodium is added to canned foods, cured meats, soft drinks, condiments and snack foods. When you think of the amount of protein and sodium your average American eats during a day full of bacon cheeseburgers, ham sandwiches, sodas and french fries, it’s not hard to see why they need more compensatory calcium than your average vegetarian!
So how much calcium do you need, then? Well, a good rule of thumb is to eat between two and five servings of calcium-rich foods – leafy green vegetables, broccoli, beans and, yes, dairy products are among your choices – while keeping your protein and sodium intake moderate. The recommended calcium-to-protein ratio is 16:1, so if you want to calculate your calcium needs, you’ll need to estimate your protein consumption first.
Surprisingly, even bread can be a good source of calcium. It was once thought that fiber and phytates, substances found in grains and nuts, bind to calcium and make in unavailable to body, which can’t absorb it. However, when yeast is present, it breaks the bond between phytates and calcium, allowing it to be used by the body – so yeast-raised breads, especially whole grain breads, can provide a degree of calcium. Also,some leafy greens are less effective sources of calcium than others – Swiss chard, spinach, beet greens and rhubarb contain substances called oxalates that limits the absorption of calcium (but they’re still chock-full of iron, so eat them anyway!)
Eating a variety of foods every day makes for a more interesting, enjoyable vegetarian way of life, so it makes sense to get your calcium from many different foods. Adequate calcium is especially important for growing children – and we’ll address vegetarian kids in Chapter 16 – so they build the strong bones they’ll need when they’re older. But you don’t need to get your calcium from milk. As we’ve discussed here, milk isn’t even good for you! Plant foods like leafy green vegetables, soy products, fortified orange juice and dried beans are loaded with calcium. And they make your menus much more fun!
