Our culture teaches us that milk and its products are an essential food group; government publications tell us that we must eat foods from each group to be healthy. Children learn that if they don’t drink their milk, they won’t grow strong bones. Adults get the impression that the best way to prevent, or even cure, osteoporosis is to drink more milk.
While milk is a key source of calcium for people consuming animal-centred diets, it is not essential to human health. As it turns out, there are a great many ways for the calcium that originates in the earth’s crust to become part of our bones. Cow’s milk is just one. Many people, dairy consumers or not, will benefit by knowing some of the plant foods that provide this mineral.
Studies show that a variety of these foods, along with the amount of calcium they contain. Amounts listed are those in the Vegetarian Food Guide,. Calcium content in plants can be expected to vary somewhat from one crop to another. There can also be great differences between brands of tofu, so check labels for nutrients. When labels state that a serving provides 10 per cent of the Recommended Daily Intake, this is based on 1,100 milligrams of calcium as 100 per cent.
Ten per cent of the Dietary Value (DV) is based on 1,000 milligrams of calcium as 100 per cent. Table takes this one step further and combines the research on availability of nutrients, or of how well we absorb calcium (where this is known) with amounts in various foods. Greens: Broccoli, Chinese Greens, Collards, Kale, Okra, and Mustard and Turnip Greens
Because calcium is an important structural component in the cell walls of leaves and many other parts of plants, various veggies can easily become important calcium contributors in our diets. In some plants (see box below), the calcium is tightly bound by plant acids called oxalates and little of it is available to us.
In contrast, many other greens are low in oxalate and are good sources of easily absorbed calcium; examples are bok choy, broccoli, collards, kale, many Chinese greens (apart from Chinese spinach), okra, and mustard and turnip greens. The proportion of calcium we absorb from these low-oxalate greens is somewhat higher than that from cow’s milk. Greens are among our best bone-builders for reasons beyond their unbeatable calcium absorption.
They’re high in vitamin K— the darker the leaf, the better. Vitamin K plays a mysterious but essential role in helping our bone-building cells perform their task. Consuming 100 grams (3.5 ounces) per day of vegetables like kale provides enough vitamin K to halve our risk of fracture.
Greens also contribute plenty of potassium to the bone-building nutrients. Kale is a hardy crop that Canadian gardeners can grow for much of the year. It’s well worth finding out how to prepare it and other greens in delicious ways
High-Oxalate Greens: Good Foods, But Not for CalciumSpinach, Swiss chard, beet greens, and rhubarb contain plenty of calcium.Unfortunately, the calcium is tightly bound by plant acids called oxalates, thus we can absorb only a small proportion of the calcium from these foods (only about 5–8 per cent), so they can’t be counted as calcium sources (see Table 4.5).
We need not avoid these high-oxalate greens, as they are rich in very important nutrients such as folate and phyto-chemicals.
In fact, scientists observe that nutrients and oxalates could actually protect us from calcium overload.