Calcium
by Dr. Neal Pinckney
heart.kumu.org
One of the most common nutritional myths is that you must eat dairy products to get enough calcium. Milk holds a special place in American culture, next to apple pie and mother. The dairy industry has convinced most of us that we can't live without their products, but there is ample evidence that we can live longer, feel better and have as much strength without milk, cheese, yogurt and all other dairy products.
Most of the calcium in the body is in our bones, with a small amount in the blood stream to aid in regulating the heartbeat, transmission of nerve impulses and muscle contraction. The amount of calcium in the blood is controlled by hormones. Calcium is continuously lost through body waste and sweat, and is replaced with calcium from the bones. As a process of normal tissue growth, the body constantly breaks down bone material and rebuilds it, using calcium from foods for replacement
Keeping bones strong depends more on preventing calcium loss than on increasing calcium intake. In nations with high rates of osteoporosis, protein intake is generally more than twice the U.S. Recommended Daily Allowance. Diets that are high in protein, especially animal protein, cause calcium to be lost through the urine. Meats are high in a particular kind of protein building block, called sulfur-containing amino acids, that cause increased calcium loss. Studies show that vegetarians have less than half the amount of osteoporosis that meat eaters have. Caffeine and sodium also increase the rate of calcium loss through urine. Alcohol inhibits calcium absorption and may also be toxic to bone. We can benefit from boron, found in fruits, vegetables, and beans, since it appears to help stop the loss of calcium. Vitamin D, copper, zinc, and weight training exercise also may increase bone mass and help to prevent osteoporosis.
The need for calcium varies at different ages. For the first 35 years our bodies lose less calcium than we consume. After 45, our body gradually loses more calcium than is taken in. The rate of calcium loss depends on how much and what kind of protein we consume. A negative calcium balance can result in osteoporosis, or fragile bones.
The body regulates how much calcium it absorbs, usually between 30% and 70% for a normal diet. If a person eats more calcium, the body just doesn't absorb it. This is a reason why high doses of calcium supplements may not prevent bone loss.
Milk is not the ideal way to get your daily supply of calcium. Milk (except skim) is high in saturated fat. It also contains high amounts of calcium-blocking protein. In addition, antibiotics fed to cows are passed on in about one third of milk sold in America. Bovine Growth Hormone is now allowed to be given to dairy cows to increase their milk supply. This hormone, usually combined with greater amounts of antibiotics, has not been subjected to long-term human testing. Although they often don't realize it, most people (about 75% of the U.S. population) have an allergy to cow's milk, called lactose intolerance. As infants, our body makes an enzyme called lactase, allowing us to metabolize the milk sugars (lactose). After childhood most people no longer make this enzyme necessary to digest dairy products properly. Human breast milk provides all the calcium a child needs and has only 6% of calories from protein, far less than the 22% in cow's milk, which is the amount needed for a calf to grow quickly. Dark green leafy vegetables are a much better source of calcium than milk, and they have almost no fat and much lower amounts of protein. Some plant sources of calcium are shown in the section Plant Sources of Calcium.