It wasn’t long ago that osteoporosis prevention education focused almost exclusively on exercise and calcium intake. The space program taught us, among many things, that weight-bearing movement here on Earth causes tiny stress fractures to our bones that are essential for healthy bones; they stimulate repair and strengthening. As osteoporosis rates have increased and physical activity levels have declined, there has been more emphasis on calcium supplementation. Recommendations have soared from 800 milligrams per day to 1500 milligrams. Unfortunately, adding more calcium into the bloodstream has not proven to be the solution.
Researchers have long known the relationship that exists between vitamin D intake (largely resulting from sun exposure) and calcium absorption. People living in northern latitudes, and in climates with less sunlight, experience higher rates of osteoporosis. Recent studies have shown that serum vitamin D levels drop 20-25% in the winter in these northern climates and may not recover in the summer where regular sunscreen usage and low dietary vitamin D intake (fortified milk, oily fish, fortified cereals and eggs) abound. Recently, the mineral magnesium was discovered as yet another piece of the puzzle; it is necessary for the activation of vitamin D. Many Americans are deficient in magnesium which is found most abundantly in whole grains, beans, and leafy green vegetables.
Researchers continue to uncover other nutrients that play a key role in the osteoporosis puzzle. Scientists have discovered that vitamin K plays an essential role in bone health; it is required for the synthesis of bone-building proteins. What makes this particularly interesting is that vitamin K is found almost exclusively in green leafy vegetables, the same source that provides calcium to most of the world’s population (who incidentally have lower fracture rates). A study of over 72,000 women found that those consuming the least vitamin K had a 30% increased risk of hip fracture compared to those consuming at least 109 micrograms daily, or the amount found in ½ cup of cooked spinach. The study also found a 45% reduction in hip fracture rates among women eating one or more servings of lettuce per day (even iceberg!) compared to those eating less than one serving weekly.1
Another recent discovery is that folate intake is strongly correlated to healthy bones. DEXA scans of the lumbar spine region of 161 postmenopausal women have shown that bone mineral density steadily increases as levels of folate increase.2 Many Americans are deficient in folate, a nutrient found in orange juice, beans, and green leafy vegetables.
What about protein? There is some evidence that higher levels of protein and specifically animal protein are linked to bone loss. There is a theory, proposed by prominent researchers, to explain how protein intake may cause calcium loss. It is called the acid-base theory and blames unhealthy diets for our poor bone health. Protein intake produces acidity in the body, however, a healthy diet full of alkaline minerals such as magnesium, potassium, and calcium (green leafy vegetables) would help the body stay balanced. In contrast, the theory goes, protein intake in addition to excessive amounts of acid producing sugar, sodium, phosphorus, caffeine, and alcohol is a prescription for bone loss. Getting enough protein appears to be important for bone health as well. Recent evidence from the Framingham Osteoporosis Study has shown that a low protein intake (less than 50 grams daily) increases bone loss.
Ecological studies in developing countries have uncovered a shocking truth: There are people on this planet with healthy bones that consume a mere 300 400 milligrams of calcium daily! This level of calcium is a far cry from the 1500 milligrams recommended by many healthcare providers today. With this new evidence, a greater emphasis needs to be placed on the absorption and retention of calcium.
Substances that cause calcium loss are caffeine (in excess of 300 milligrams daily - two strong cups of coffee or four cups of tea), sodium (40 milligrams calcium lost per 1000 milligrams sodium), phosphorus (found in soft drinks and other processed foods) and alcohol (more than one drink daily). The consensus on alcohol intake at this time is that two or more drinks daily for women can increase hip fracture risk. Interestingly, a study of nearly 500 older women found that women drinking one to two drinks per week had significantly higher spine, total body, and midradius bone mineral density than did nondrinkers.3
In conclusion, while the scientists are trying to unravel this mystery, individuals that exercise regularly, expose themselves to healthy amounts of sunshine, and eat a whole foods diet based around dark green leafy vegetables, fruits, beans, nuts and seeds, and lean sources of protein are taking the right steps toward osteoporosis prevention.