Calcium and the Vegan Diet
Of all the nutrients of special interest to vegans, calcium may require the most effort to get. Sure, other nutrients demand attention too, but for the most part they’re all quite easy to obtain. Needs for Vitamins D and B12 are easily covered by popping supplements every two or three days. As for protein, there are tons of vegan foods loaded with it, plus you can always turn to vegan protein powder if you’re falling short. Omega 3 needs can be met with a daily tablespoon of ground chia, plus a capsule or two of vegan DHA/EPA.
Attending to your body’s requirements for calcium requires greater care than what’s needed for the above nutrients, since most foods are relatively low in calcium and most people don’t supplement for this nutrient. Supplementing would indeed be a wise choice for many vegans and non-vegans.
Dairy Products and Calcium
Sometimes (often, really), people on both sides of an argument get their main points spectacularly wrong. That’s never been more the case than in the dispute between dairy interests and vegans regarding calcium. The dairy people seem at times deliberately misleading, whereas the vegans have trotted out their share of misinformation as well.
Using the classic “get ’em while they’re young” strategy, the dairy industry has put calcium needs for growing children and adolescents at the very center of their marketing. By using the “calcium, calcium, calcium” mantra, and holding up milk as a uniquely good source of this nutrient, they’ve created the impression that no calcium source rivals milk. But, as we’ll soon discover, that just isn’t true. On top of this, the dairy marketing boards never seem to volunteer the fact that the vast majority of the world’s population has trouble digesting milk. About 65 percent of the world’s adults are lactose intolerant. And that figure is much higher among people of African and Asian descent—around 99 percent of adults of Chinese descent are lactose intolerant.
Unfortunately, vegan advocates don’t have a good track record either when it comes to accurately discussing this nutrient. A number of vegan books and websites assert that dairy is, in reality, a poor source of calcium. The claim is that the substantial amount of protein found in dairy products results in loss of calcium from bones. Often, this argument is accompanied by charts showing the rates of hip fracture in various countries, making it appear that the more dairy consumed the greater the rates of hip fracture. This entire line of thinking has, however, been thoroughly debunked. It turns out that protein may have less effect on bone loss than previously thought. In fact, it appears to be beneficial since it improves calcium absorption. As for the hip fracture argument, there are confounding factors that make pointing to this statistic dishonest. For example, hip fracture rates are highest in high-latitude locations with lots of ice on streets and sidewalks—and ice is of course closely associated with falls. On top of that, these high latitude areas tend to mean people have lower vitamin D status, which results in diminished bone health.
As we’re about to see, it’s nonsense to assert that dairy plays an irreplaceable role in ensuring adequate calcium consumption. But the position some vegans take regarding calcium is even less aligned with the truth. The reality is that it’s quite possible for a daily milk drinker to see her calcium status decline by going vegan—if she doesn’t make the effort to add calcium-rich vegan foods to replace the dairy products she has stopped consuming.
How much calcium does a person need?
As with every other nutrient, there’s no hard and fast intake number that applies to everyone. Also, optimum intake varies at different ages, being highest during teen years and old age. Absorption rates differ from person to person, so when governments and nutritional councils set targets they try to err on the high side to ensure that the guideline will meet the needs of upwards of 95 percent of the population. Setting the target level for any nutrient is an inexact science, but an informed guess is obviously more helpful than no guess at all.
The Institute of Medicine in the United States sets recommendations for calcium at 1300 mg. for people age nine to eighteen, 1000 mg for adults, and 1200 mg. for women over fifty and men over seventy. These numbers are probably not exactly right, but they’re the best we’ve got and it therefore makes sense to plan your diet in a way so that you can hit these recommendations.
Meeting Your Needs with Vegan Foods
Now that we know that you need something like 1000 to 1300 milligrams of calcium each day, reaching this number becomes largely a matter of simple arithmetic. Here is what various calcium-rich vegan foods deliver:
- Tofu (1 Cup. Must have calcium sulfate listed in the ingredients): 861 mg (181 Calories)
- Soy Milk (1 Cup, calcium-fortified, unsweetened): 300 mg. (79 Calories)
- Collard greens (1 Cup, cooked): 268 mg. (63 Calories)
- Mustard greens (1 Cup, cooked): 165 mg. (36 Calories)
- Bok-Choy (1 Cup, cooked) 158 mg. (20 Calories)
- Kale (1 Cup, chopped, cooked): 94 mg. (36 Calories)
- Black Beans (1 Cup, canned) 84 mg. (218 Calories)
- Tahini (1 Tablespoon, roasted): 64 mg. (89 Calories)
- Broccoli (1 Cup, chopped, cooked): 31 mg. (27 Calories)
For comparison, whole milk supplies 276 mg. per cup, with each cup providing 149 calories. So you can see that cow’s milk is an excellent source of calcium, but fortified soy milk is too. And on a per-calorie basis, bok-choy has more than four times as much calcium as whole cow’s milk.
The above figures are useful to keep in mind, but they’re also a lot to take in and make sense of. With many calcium-rich vegan foods, the limiting factor of how much you’d want to eat in a day isn’t related to calorie content, but instead to how bulky these foods are. For instance, kale contains a great deal of calcium per calorie. The trouble is that this calcium is accompanied by a whole lot of bulk. If you tried to meet your daily calcium needs solely through cooked kale, you’d have to eat ten cups a day. You’d have to be deranged to attempt that! Even worse would be the prospect of trying to meet your needs through black beans alone. Just imagine what eating more than ten cups of beans in a day would do to you.
There’s certainly no question that you could get sufficient calcium by eating some combination of beans, greens, and broccoli. But your diet would be on the strange side, and would be bulkier than many people prefer. That’s why the addition of some calcium-fortified soy milk or some calcium-set tofu can make all the difference (Always make sure that your tofu lists calcium sulfate in its ingredients, otherwise it’s not a good source of calcium.)
Together, tofu and vegan milks can transform the task of getting sufficient calcium from tricky to easy. For example, just by drinking a cup of soy milk with breakfast, and then including a half-cup of tofu as part of your lunch, you’ve already met half your daily calcium needs. From there, you need only eat a relatively small amount of beans and greens to put yourself over the top.
Some people might object that eating calcium-set tofu and fortified soy milk isn’t “natural,” but there isn’t any reason why calcium obtained this way is inferior to getting this mineral from vegetables or from cow’s milk.
Every sort of leafy green contains a substantial amount of calcium. But there’s an important caveat to keep in mind: several popular greens are loaded with oxalates (oxalic acid). These oxalates interfere with calcium absorption. Oxalates won’t cancel out all the calcium your greens contain, but they can interfere with absorbing most of it. So if you’re eating greens with the intention of boosting your calcium intake, you’ll want to avoid spinach, chard, and rhubarb—all of which are rich in oxalates. Note that if you choose to boil oxalate-rich greens, some of the oxalic acid will leech out into the water, improving calcium absorption if the cooking water is discarded.
The greens mentioned in the previous section—collard greens, mustard greens, bok-choy, and kale—are all low in oxalates, and are therefore superb sources of calcium.
If you’re having a hard time getting sufficient calcium through food alone, supplements offer an easy way to close the gap. Depending on the brand (check the label), just one tablet can give you a whopping 500 to 1000 mg. of this nutrient, enabling you to easily elevate your status from inadequate to excellent. Deva Nutrition manufactures an excellent and affordable vegan supplement that contains a big dose of both calcium and magnesium.
But don’t just start gobbling supplements without paying heed to your total intake. Too much calcium can easily lead to kidney stones (which are excruciating to pass), so make sure that your combined intake from food and supplements doesn’t exceed 1300 mg. per day.
Vitamin D and Exercise
Articles about bone health tend to focus on calcium consumption, but there are two more important factors to consider: vitamin D and exercise.
Bones are not simply inert calcium. They’re actually full of specialized cells called osteoblasts and osteoclasts, which work together to maintain bone strength and prevent brittleness. Just like you need a steady flow of oxygen coming into and then leaving your bloodstream, the same is true of the minerals that enter and leave your bones. Every day, a tiny portion of your skeleton is broken down by osteoclasts. As this is accomplished, osteoblasts then take calcium from your blood and assemble it into a fresh new calcium matrix. The greater the rate at which calcium circulates in this way, the stronger and less prone to breakage your bones will be.
So as you can see, calcium intake is only part of the story where bone health is concerned. If you don’t have proper functioning of osteoblasts and osteoclasts, even a huge intake of calcium won’t give you adequate bone health.
As people age, their bones grow more brittle and more likely to break during falls. This brittleness is chiefly caused by poor osteoclast function. So how can you ensure that you’ve got sufficient osteoclasts, and that they’re functioning properly to remove old calcium from your bones? First, you want to make sure you’re taking in adequate vitamin D, since this nutrient is essential for proper osteoclast formation.
Second, everybody needs regular weight-bearing exercise. Weight lifting of any kind obviously qualifies as weight-bearing exercise. That’s true whether you’re doing he-man 200 kilogram bench presses or toying around with 1 kilogram dumbbells. Cheap portable resistance bands deliver the same weight-bearing benefits (in fitness parlance, both weight lifting and resistance bands are lumped together as “resistance exercise.”) And there are numerous other types of weight bearing exercise, including: walking, hiking, jogging, climbing stairs, tennis, and dancing.
The two most popular exercises that are not considered weight-bearing are swimming and bicycling. These are great activities to boost aerobic conditioning, but they can’t be counted on to improve bone health. If the connection between exercise and bone health makes you to want to increase your fitness level, you’ll find our Guide to Vegan Fitness of interest. You’ll discover that it’s easy to elevate your activity level without the task ever become drudgery. And it takes a far smaller commitment to achieve real benefits than most people think.
The Three Takeaways
If you don’t drink cow’s milk and you never give calcium a thought, it’s likely that you’ll suffer poor bone health later in life. But there’s no need to take any risks on this front, since it’s easy to meet your nutrient needs on a vegan diet, while laying the groundwork for a lifetime of strong bones. The three core recommendations are:
- Get your 1000 to 1300 milligrams of calcium each day. If you can’t get all of this through food, then take a supplement but be sure not to surpass 1300 milligrams total consumption per day.
- Tack on a half hour or more of daily weight-bearing exercise.
- Make sure you’re getting adequate vitamin D. For most people, especially those in temperate climates, that means taking a vitamin D supplement.
Vegans and omnivores alike often pay insufficient attention to calcium intake, a fact reflected by the millions of bone fractures occurring due to osteoporosis each year. Fortunately, a well-planned vegan diet coupled with adequate exercise can ensure excellent calcium status today, and good bone health later in life.
For further reading: “Protecting Bone Health on a Vegan Diet,” by Virginia Messina, MPH, RD.