Fitting Fitness Into Busy Life
Improve Bone Density Naturally: How Dietary Habits Affect Absorbable Calcium
I received an interesting question about the role of phytates on bone health, and more specifically their role in the prevention of osteoporosis. Since it is well known that phytates strongly bind to minerals such as calcium, it seems counterintuitive that many dietary recommendations for osteoporosis suggest eating foods rich in fruits, vegetables, and legumes. In point of fact, one research study showed that persons who consumed a diet rich in phytates had improved bone density, relative to those individuals who consumed a diet lower in phytate-containing foods.
Absorbable Calcium
The consensus opinion from multiple sources is that calcium is best obtained from a variety of food sources, with supplements being a second line of defense. Recommendations for daily calcium intake can be found in the following table.
Recommended Daily Intake For Calcium
| Age | Calcium (milligrams per day) |
|---|---|
| 0-6 Months | 210 |
| 6-12 Months | 270 |
| 1-3 Yrs | 500 |
| 4-8 Yrs | 800 |
| 9-18 Yrs | 1300 |
| 19-50 Yrs | 1000 |
| 51+ Yrs | 1200 |
| Pregnant or Lactating | 1000-1300 |
We can process a maximum of 500 milligrams of calcium at a time, so most experts suggest spacing out our calcium consumption over the course of the day. Since only about 10% of the calcium in foods is absorbable, it becomes more obvious why consumption should be spread out evenly. Taking this approach helps regulate calcium levels, and improves our use of the mineral.
How To Improve Bone Density Naturally
Unfortunately, there are a variety of foods that have the potential to interfere with our ability to process calcium. Chief among them are caffeine, which can bind to calcium and cause it to be excreted in urine. Another bad actor is oxalic acid, which is common in green leafy vegetables. Research has shown that any calcium found in foods which also contains oxalic acid can not be absorbed by our digestive systems. Fortunately, oxalic acid doesn’t seem to interfere with the absorption of calcium in other foods.
That leads us to phytates. Found in foods that traditionally have high concentrations of fiber, phytates and phytic acid bind strongly to all divalent metals, including iron and calcium. Much of the published literature suggests one avoid eating high calcium and high phytate foods together, for fear of the phytate complexing with calcium and reducing its bio-availability. Yet other research has shown that a diet low in phytates may be a risk factor for developing osteoporosis. Fortunately, a research paper published in the Journal of Nutrition may explain this contradiction.
It turns out that the relationship between high phytate foods and calcium depends depends on the amount of phytate being consumed. When subjects consumed milk with bran-based foods, which are very high in phytates, the availability of calcium for digestion was quite low. By contrast, drinking milk with foods that have more moderate concentration phytates actually increased the absorbable calcium level during digestion. In fact, drinking milk with whole wheat products increased the available calcium over drinking milk alone. Researchers speculate that different calcium-phytate complexes are formed, based on the concentration of phytates present, with higher phytate levels forming stronger complexes.
So, we can now see yet another advantage to consuming whole wheat, nuts, and legumes. In spite of their potential pitfalls, it substantiates the recommendation that a diet consisting of moderate amounts of phytates in conjunction with calcium, makes the calcium more available to improve bone density naturally.
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