You Ask, I Answer: Cabbage, Radishes, Calcium

My family eats a ton of red cabbage.

Is this a fairly healthy, cruciferous vegetable and a good source of calcium?

What about radishes?

-- Dennise O'Grady
Bay Head, NJ

Like all other cruciferous vegetables, red cabbage offers a wonderful array of unique phytonutrients and flavonoids that have been shown to help reduce the risk of a variety of cancers, particularly colorectal and bladder).

It is not, however, a good source of calcium. Unlike some of its calcium-powerful relatives (bok choy, broccoli, kale, mustard greens, and turnip greens), its absorption rate is quite low.

Whereas slightly less than one cup of kale steamed kale provides the same amount of calcium as a half cup of milk, you need three cups of steamed cabbage to reach that same amount.

Slight aside: For maximum absorption of all nutrients and components, opt for steamed, rather than raw, cabbage.

Radishes do not particularly stand out from a nutrient composition standpoint. Although they offer almost every single vitamin and mineral, each one occurs in small amount.

Alas, nutrition isn't solely about vitamins and minerals. The antioxidants that give radishes their natural hue are very beneficial to health.

As with cabbage, radishes are not your best source of calcium. Due to their low absorptive qualities, it takes four and a half cups to match the amount of absorbable calcium in a half cup of milk.

The Lowdown on Calcium

Calcium is one of the most misunderstood nutrients.

The range of confusion varies from those who think dairy products contain the most absorbable type of this mineral to people who think spinach is a great source of calcium.

Let's clarify these points.

Are dairy products a good source of calcium? Yes. After all, eight ounces of milk provide a third of the daily value of calcium.

Are dairy products the only way to get calcium? Absolutely not.

Do dairy products provide calcium with the highest bioavailability? No.

Consider the following:

Eight ounces (one cup) of milk contain 300 milligrams of calcium.

A half cup of cooked bok choy provides 79 milligrams of calcium.

To someone unfamiliar with nutrition, the conclusion might seem obvious: "I need two cups of bok choy to get as much calcium as a cup of milk!"

Alas, nutrition science isn't always as obvious as it seems.

You actually only need one and a quarter cups of cooked bok choy to match the calcium you would get from a cup of milk since the calcium in bok choy is more absorbable than the one in dairy products.

The same thing happens with Chinese cabbage. A half cup of this cooked vegetable offers 239 milligrams of calcium, but that equals the amount of absorbable calcium in a cup of milk.

Let's now turn our attention to spinach. I am continually amazed by the amount of self-touted (though, clearly, not really) nutritione experts who list this vegetable as a good source of calcium.

A half cup of cooked spinach offers 115 milligrams of calcium. However, due to its high amount of oxalates (organic acids naturally found in spinach that inhibit calcium absorption), it takes EIGHT cups of cooked spinach to equal the amount of absorbable calcium in one cup of milk.

It just so happens that unlike spinach, the Brassica family of plants -- including broccoli, kale, bok choy, cabbage, and mustard greens) does not accumulate oxalate, thereby providing highly absorbable calcium.

I know some people like their nutrition advice in absolute form ("NEVER eat this, ALWAYS eat this), it's not my style.

My suggestions provide you with plenty of choices. If you like milk, drink it -- it provides a significant amount of calcium.

If you don't like it or don't want to include it in your diet, no need to worry about calcium as long as you include greens from the Brassica family and other non-dairy sources (tofu, tempeh, almonds, calcium-fortified alternative milks, etc.) in your diet.