Vegan for Life - Jack Norris [21]
In the United States, we refer to the lack of this enzyme as “lactose intolerance.” But that’s definitely a western bias since this “intolerance” is not a lack or an abnormality; it’s part of normal human development in most people. Since many people the world over need to meet calcium needs without dairy foods, there is no reason why vegans can’t do it as well. And with our access to a wide variety of calcium-rich and fortified foods, it’s not at all difficult.
Meeting Calcium Needs on a Vegan Diet
The amount of any nutrient in a food is not equal to the amount that actually makes its way from the intestines into the bloodstream. The bioavailability of a nutrient from a particular food refers to the amount of that nutrient that is likely to be absorbed and used, and it’s affected by a number of factors.
A few leafy green vegetables—spinach, beet greens, Swiss chard, and rhubarb—are high in naturally occurring compounds called oxalates that bind calcium and make it essentially unavailable to the body. But the availability of calcium from low-oxalate vegetables—kale, collards, broccoli, and turnip greens—can be as high as 50 percent.16 Calcium absorption from soyfoods, like calcium-set tofu (tofu that is processed with calcium-sulfate) and fortified soymilk, is around 25 to 30 percent, which is about the same as from cow’s milk. Calcium absorption from nuts and legumes is somewhat lower, around 20 percent.
The recommended intake of 1,000 milligrams of calcium is based on the assumption that most people absorb around 30 percent of the calcium in their diet. If you’re eating a varied diet that includes several different types of calcium sources, including leafy greens and soy products, you don’t need to worry that some of the calcium from other foods is absorbed less efficiently.
It’s possible to get plenty of calcium just from eating foods that are naturally rich in this mineral, but it does take some effort. (This is equally true for people who consume dairy foods, since many people who drink milk don’t meet calcium requirements. That’s why so many products on the market—from cereals to juices to protein bars—are fortified with calcium.) Using fortified foods like juices and nondairy milks can make it easier to meet calcium recommendations on a vegan diet.
It’s also helpful to pay attention to the effects of processing. For example, frozen leafy greens are higher in calcium than fresh, although this is simply because their volume tends to be more concentrated. Processing also affects the amount of calcium in different types of tofu. Tofu production involves ingredients that cause soymilk to curdle. The two most common—often used together—are magnesium-chloride (nigari in Japanese) and calcium-sulfate. When calcium-sulfate is used, tofu is often an excellent source of calcium. Also, firm tofu tends to have a higher calcium content than soft. It’s important to read package labels, though, since the amount of calcium in different brands and different types of tofu varies widely.
In the Vegan Food Guide in Chapter 7, we recommend 6 to 8 servings of calcium-rich foods per day. This allows you to mix and match small servings of a variety of calcium-rich foods or get all of your calcium from larger amounts of just a few foods. One serving is ½ cup fortified plant milk or juice, ½ cup cooked, calcium-rich vegetables, ½ cup tofu or tempeh, 2 tablespoons almond butter or tahini, ¼ cup soynuts, or ½ cup dried figs. The table on page 45 shows calcium contents of a wide variety of plant foods.
CALCIUM CONTENT OF PLANT FOODS IN MILLIGRAMS
Food Calcium Content (in milligrams)
Legumes
(½ cup cooked)
Black beans 51
Chickpeas 40
Great northern beans 60
Kidney beans 25
Lentils 19
Lima beans 16
Navy beans 63
Pinto beans 40
Vegetarian baked beans 43
Tofu
(½ cup)
Firm, prepared with calcium sulfate 150–300
Firm, prepared with calcium