Got Milk? And does it matter if you do?
Our bones are the structure to our entire body. They hold us up, protect our organs, they make red blood cells in our marrow, they store essential minerals and provide structure for our muscles. For years we have been told to drink our milk and our bones will be strong. We won't get osteoporosis, a debilitating disease evidenced by weak, brittle bones. But does current research support the milk and bone health relationship?
Bone health is affected by many things, including nutrition, genetics, physical activity, body weight, smoking or exposure to second- hand smoke, alcohol use, hormone levels and medications. The theory has been that when you do drink milk you get calcium, one of the primary minerals needed for bone formation. Calcium is needed in the body for many important functions. When blood levels of calcium drop our bodies pull needed amounts from our bones to normalize blood levels of the mineral. You will see an increase of calcium in the urine, theoretically meaning that your body is leeching the mineral from your bones.
Proponents of dairy-free diets promote the fact than many countries with the lowest rates of osteoporosis also consume very little milk. Milk is an acidic food that causes increased amounts of calcium to be pulled from the bones to return the blood pH level to normal. However, studies show that the acid residue of the diet does not affect the overall calcium status of the body. Our bodies are extremely smart and actually compensate for these calcium losses by increasing the amount of calcium absorbed from foods. The whole calcium balance seems to be handled by the digestive system and kidneys more than from the skeletal system.
Drinking milk may increase your risk for heart disease and prostate cancer. So what other options are there? Calcium is also found in dark green leafy vegetables, broccoli, edamame, canned fish, white beans and fortified foods. A lot of the vegetables high in calcium also happen to be high in vitamin K - another nutrient that is essential to bone health.
Vitamin D is also essential for bone health. There are very few natural food sources of vitamin D. Sources are primarily the flesh of fatty fish (salmon, tuna and mackerel), and so it is commonly supplemented in milk. The body is also able to make its own Vitamin D from sunshine. The link between vitamin D and vitamin K may provide insight as to why those countries with low milk consumption have strong bones. They eat plant foods that are high in calcium and vitamin K and tend to have more exposure to Vitamin D via sunlight. Americans also tend to eat very high protein diets which can lead to an increased need for calcium.
With adequate calcium and physical activity, bone production exceeds bone break down until approximately age 30. After that, breakdown typically exceeds production. Rates of bone loss increase sharply in postmenopausal women due to lower estrogen levels. Unfortunately, supplementation of single nutrients such as calcium, Vit D or Vit K have proven to have little effect on maintaining strong bones. Once again, eating healthful foods in healthy amounts is your best bet.
For strong bones the following lifestyle choices will provide the best results. Get regular exercise, especially weight-bearing and muscle strengthening exercise. Get adequate vitamin D through either diet, supplements or exposure to sunshine. Consume enough calcium from either dairy or plant based sources. Eat green leafy vegetables to get plenty of Vitamin K.