Growing scientific evidence suggests that the same type of diet that promotes atherosclerosis (hardening of the arteries) may also promote osteoporosis. When most people think of high LDL (“bad” cholesterol) levels in the blood, they associate it with clogged arteries and an increased risk of cardiovascular disease. However, research is now indicating that higher levels of LDL in the blood may not only lead to blocked and calcified arteries but also thinned and decalcified bones. If this theory proves correct, then the reason that a diet high in animal products promotes osteoporosis may have more to do with their fat and cholesterol content than their protein content.
How could high LDL contribute to osteoporosis? Just as LDL particles can move from the blood and into arteries, they can also enter bones. In the artery wall, these white blood cells (called monocytes) turn into macrophages that engulf modified LDL particles and turn into “foam” cells. The accumulation of these cells leads to atherosclerotic plaque.
In the bone, increased LDL can also attract more monocytes, which turn into osteoclasts. Osteoclasts eat away surrounding bone structure like miniature Pacmen. When LDL levels are in the healthy range (50-100mg/dl), the bone-eating activity of these macrophages is offset by another bone cell known as an osteoblast, which constantly builds up new bone tissue. As LDL levels rise in the blood and bone, the activity of osteoclast becomes greater. At the same time, oxidized LDL in the bone inhibits the formation of osteoblasts. As a result of increased LDL in the bone, overall bone mineral density declines. Over time, elevated LDL levels can contribute to the development of osteoporosis. Research has shown that drugs and diets that lower LDL can reduce the loss of bone in animals and/or human subjects.* The consumption of milk and dairy products may have both positive and negative effects on bone health. The very high saturated fat and cholesterol con- tent of full and even low-fat dairy products may raise LDL levels enough to offset the beneficial effects of the extra vitamin D and calcium they supply. Unless LDL are below 100 mg/dl, it seems wise to advise people at risk for either atherosclerosis or osteoporosis to limit all dietary sources of saturated and hydrogenated fat as well as cholesterol.
* Parhami F, Garfinkel A, Demer LL. Arterioscler Thromb Vasc Biol 2000;2346-8
By Dr. James J. Kenney PhD, RD, FACN
Brought to you by the Nutrition Education Store. Want to learn more about the connections between diet and health? Check out our posters, handouts, presentations, books, recipe files, games, and more!
Judy’s passion for cooking began with helping her grandmother make raisin oatmeal for breakfast. From there she earned her first food service job at 15, was accepted to the world-famous Culinary Institute of America at 18 (where she graduated second in her class), and went on to the Fachschule Richemont in Switzerland where she focused on pastry arts and baking. After a decade in food service for Hyatt Hotels, Judy launched Food and Health Communications to focus on flavor and health. She graduated with Summa Cum Laude distinction from Johnson and Wales University with a BS in Culinary Art, holds a master’s degree in Food Business from the Culinary Institute of America, 2 art certificates from UC Berkeley Extension, and runs a food photography studio where her love is creating fun recipes.
Judy received The Culinary Institute of America’s Pro Chef II certification, the American Culinary Federation Bronze Medal, Gold Medal, and ACF Chef of the Year. Her enthusiasm for eating nutritiously and deliciously leads her to constantly innovate and use the latest in nutritional science and Dietary Guidelines to guide her creativity, from putting new twists on fajitas to adapting Italian brownies to include ingredients like toasted nuts and cooked honey. Judy’s publishing company, Food and Health Communications, is dedicated to her vision that everyone can make food that tastes as good as it is for you.