Contrary to popular belief, calcium doesn’t only come from cows! Crazy huh? A lot of marketing money stemming from the Dairy Industry has led us to believe that dairy is the one and only superstar in the battle against osteoporosis, which isn’t the full truth. Whether you are a vegan, environmentalist, lactose intolerant or just love your green leafy vegetables, there are other dietary options for healthy bones.
Three Factors Influencing Calcium – Intake, Excretion & Absorption
It is important to understand that calcium status is not simply a matter of calcium intake, but of calcium balance – intake, absorption and excretion all have important impacts on bone density.
1. Calcium Intake On A Dairy Free Diet
The Recommended Daily Intake for calcium is 1000mg per day for most populations. Sourcing your calcium solely from plant foods can be challenging. If you avoid all dairy products the use of calcium fortified foods may be necessary. Here are some top contenders of calcium rich plant foods.
- Collard Greens, 1/2 cup cooked – 113mg
- Figs, 5 – 88-137mg
- Oranges, 1 med – 52mg
- Tofu, silken firm 1/2 cup – 40mg
- Seaweed, 1/2 cup raw – 67mg
- Okra, 1/2 cup cooked – 50mg
- Broccoli, 1/2 cup cooked – 30mg
- Kale, 1/2 cup raw – 90mg
- Bok Choy, 1/2 cup cooked – 78mg
- Chinese cabbage flower leaves, 1/2 cup cooked – 239mg
- Chinese mustard greens, 1/2 cup cooked – 212mg
- White beans, 1 cup cooked – 226mg*
- Pinto beans, 1 cup cooked -90mg*
- Almonds, 1/4 cup – 80-115mg*
- Sunflower seeds 1/4 cup – 42mg*
- Tofu, firm, calcium-set, 1/2 cup – 860mg
- Fortified soy and grain milks, 1/2 cup – 100-150mg
The above are low oxalate options
*These foods are high in phytates which may somewhat affect the absorption of calcium. Soaking and sprouting help to reduce the phytate content of these foods.
Where Did Our Ancestors Get Calcium From?
It has been estimated that our ancient ancestors consumed around 1500-3000mg of calcium per day, and they didn’t get it from cows. We know that calcium is the fifth most abundant mineral in the earth’s crust and that plants take up this calcium as they grow. Many of the plants our pre-historic ancestors consumed are not commonly eaten today.
In Canada, our Aboriginal people traditionally got their calcium from calcium salts, such as the calcium carbonate, from limestone. Native American people ground corn in clay bowls, and the resulting corn flour became “fortified” with calcium carbonate.
2. Factors Affecting Calcium Loss From Our Body
No matter how much calcium we consume, some will always be lost through our urine and feces. Some dietary factors can increase these losses from our bodies.
Proteins Effect on Calcium
Amino acids are the building blocks of protein. Some of these amino acids contain sulfur which has an acidifying effect on blood. A high protein diet can cause your blood to become too acidic and your body attempts to neutralize the blood by drawing calcium, which is basic, from the bone. Although all protein, even from plants, can lead to calcium losses, it is meat that is especially high in the sulfur containing amino acids leading to higher rates of calcium loss.
Sodium and Its Effect on Calcium Losses
Sodium or salt is present all around us, and often we take in more that we need. When we eat too much sodium, our kidneys excrete the excess sodium and take small amounts of calcium along with it.
Soft Drinks and Coffee and Their Effects on Calcium Losses
Don’t worry coffee lovers, up to 3 cups of coffee per day appears to have a negligible effect on calcium balance, though it is possible that more than this amount could increase calcium loss. Soft drinks such as cola are high in phosphoric acids and a high consumption could increase calcium loss.
3. Factors Affecting Calcium Absorption In Our Bodies
Some foods may appear to be a good source of calcium but there are a few things to keep in mind when considering how much of that calcium is absorbed by our bodies.
Timing of Calcium Rich Meals
Our body absorbs more calcium from food when a small amount is eaten at one time. Eating calcium rich foods throughout the day rather than all at once will increase overall absorption.
Bioavailability means the proportion of a nutrient in a food, such as calcium, that we can actually use. The calcium in green vegetables has a high bioavailability and ~40-60% of the calcium is utilized. Milk and calcium-set tofu has about a 30% bioavailability of calcium. The calcium from soy beverages – often fortified with tricalcium phosphate – is a little lower at 24%. Legumes, almonds, sesame seeds and sweet potato have lower bioavailability at ~20%. Spinach, beet greens, Swiss chard and rhubarb are high in oxalates which prevent much of the calcium from being absorbed.
Vitamin D Increases Calcium Absorption
Foods sources high in vitamin D are minimal – oily fish and eggs being the main contenders. We can also get our vitamin D from sunlight. Unfortunately during October – March for anyone above the 45th latitude, there is not enough UV light for adequate vitamin D production. Vitamin D is essential for the active absorption of calcium in your body.
Calcium and the Other Major Players For Bone Health
There are many other factors that favourably affect bone health. Aside from sufficient calcium and vitamin D, magnesium and protein (not in excess) are also important for strong bones. Research suggests that boron which is plentiful in fruits, leafy vegetables, nuts and legumes may have a beneficial impact to.
Want Strong Bones? Start Young
There is nothing pretty about osteoporosis. The overall process to achieve maximum bone strength takes about 20-30 years. Up until the age of 8 we achieve a ~45% gain in bone mass, with another 45% occurring from ages 8-16. The last 10% occurs over the next decade and a half. After age 30, bone mass is on the decline.
If you’re still in your 20s there is still time to build up your bones. Past 30? Don’t worry, a healthy diet with adequate calcium from vegetables low in oxalates, avoidance of excess salt and sodas, and a reduction in proteins high in sulfur can help keep your bones strong. Adequate vitamin D is important and consider supplementing during the winter months depending on your location. And of course, weight bearing exercises can help reduce the rate of declination of your bones. Remember, there is nothing wrong with a little dairy in your diet (assuming they are happy cows), and if you do avoid all dairy carful planning is required and professional guidance may be warranted.
References For Maximising Calcium On A Dairy Free Diet
Book:Becoming Raw – Brenda Davis, RD
Book:Becoming Vegan – Brenda Davis, RD