14 DAY TRIAL // Going hungry and taking pills won't help you keep strong bones. A new research at Washington University School of Medicine in St. Louis has found that females who obtain most of their daily calcium from food have stronger bones than those taking calcium mainly from supplemental tablets. And this conclusion persists even when the supplement intake overcomes calcium intake from food.
Calcium shortage helps the osteoporosis development, a condition affecting 8 million American women and 2 million American men. Some 34 million Americans have low bone mass, risking to suffer from osteoporosis. Right calcium intake keeps bone density by allowing the organism not to steal necessary calcium from the bones.
The research was made on 183 postmenopausal women. The women had to meticulously detail their diet and their calcium supplement consumption during a week.
"We assumed that this sample represented each woman's typical diet. In addition to analyzing the volunteers' daily calcium intake, we tested bone mineral density and urinary concentrations of estrogen metabolites," said senior author Dr. Reina Armamento-Villareal, assistant professor of medicine in the Division of Bone and Mineral Diseases and a bone specialist at Barnes-Jewish Hospital.
The women could be assigned into three groups: the "supplement group" achieved at least 70 % of their daily calcium from tablets or pills; the "diet group" got at least 70 % of their calcium from dairy products and other aliments; and the "diet plus supplement group" somewhere in between these ranges.
The "diet group" consumed the least dosage of calcium, an average of 830 milligrams daily. Still, this group had higher bone density in their spines and hipbones than individuals in the "supplement group" who took approximately 1,030 mg/day. Those in the "diet plus supplement group" had the highest bone mineral density as well as the highest calcium consume at 1,620 mg/day. Estrogen, a female sex hormone, maintains calcium in the bones but the standard form is broken down or metabolized in the liver to other forms, some active and some inactive. Analysis of urine sample revealed that women in the "diet group" and the "diet plus supplement group" presented a higher ratio of active to inactive estrogen metabolites than those in the "supplement group."
"This suggests that dietary calcium is associated with a shift in estrogen metabolism that favors production of active forms of estrogen. Although we're not yet certain what underlies this effect, it could be that nutrients other than calcium cause this shift. It's also known that dairy products, which are a major source of calcium, can contain active estrogenic compounds, and these can influence bone density and the amount of estrogenic metabolites in the urine." said Armamento-Villareal.
Also, the way calcium is absorbed differs amongst supplements, and could be a factor influencing the final results. Calcium carbonate tablets have to be ingested with a meal so that stomach acid can ease absorption, while calcium citrate tablets are not limited by this.
"Only about 35 % of the calcium in most supplements ends up being absorbed by the body. Calcium from the diet is generally better absorbed, and this could be another reason that women who got a high percentage of calcium in their food had higher bone densities. Although dairy foods are excellent sources of calcium, individuals with dairy sensitivities could consume other calcium-rich food sources such as calcium-fortified orange juice (which contains calcium citrate)." said Armamento-Villareal.
Dark green leafy vegetables also have high calcium levels, but this is harder to absorb than dairy calcium.