February 2021 Issue
Update on Osteoporosis — What You Should Know About Dietary Recommendations and the Latest Therapeutics
By Densie Webb, PhD, RD
Today’s Dietitian
Vol. 23, No. 2, P. 34
In the midst of a pandemic, it’s easy for clients to forget about other pressing medical conditions they urgently need to focus on for prevention or treatment. These may include osteoporosis and low bone mass, which, according to the National Osteoporosis Foundation (NOF), affect about 54 million Americans. Of those, an estimated 10 million have osteoporosis, and 34 million people have low bone mass, putting them at future risk of osteoporosis.1
To further emphasize the gravity of the disease, the NOF points to studies suggesting that approximately 1 in 2 women and up to 1 in 4 men aged 50 and older will break a bone at some point in their lives due to osteoporosis. Virtually all hip fractures are attributed to osteoporosis and are most common in people older than 65, with women having twice the rate of hip fractures of men. In fact, 71% of all osteoporotic fractures occur among women.2,3 After a hip fracture, only a subset of women regain their prefracture quality of life—up to 17% end up in a nursing facility. As much as 23% will die within two years post fracture, and that proportion increases significantly with age—as high as 32% for women aged 85 and older.4 These alarming statistics make osteoporosis prevention a health priority.
Osteoporosis 101
Osteoporosis literally means “porous bone.” In severe cases, the bone can have a Swiss cheese appearance on X-ray. In such severe cases, bones may become so fragile that something as simple as opening a window, coughing, or sneezing can cause bones to fracture. But before a client or patient reaches that stage of osteoporosis, they may be diagnosed with osteopenia or thinning bone, which simply means they’re losing bone faster than they can replace it, and it needs to be addressed.2
Aside from gender and age, many factors determine osteoporosis risk, such as smoking, alcohol consumption, chronic treatment with glucocorticoids, long-term treatment with estrogen blockers, gastrointestinal disorders, type 1 and type 2 diabetes, rheumatoid arthritis, liver disease, gluten enteropathy, and hematologic disorders.2 Even air pollution has been suggested to contribute to risk.5
Some unchangeable risk factors, such as age, gender, and race, determine up to 75% of peak bone mass. However, changes in diet and activity beginning at an early age can affect the 25% that’s within an individual’s control.6 So, it’s important to remember that risk actually begins in childhood. In fact, the office of the Surgeon General states that “prevention of bone disease begins at birth and is a lifelong challenge.”7 During childhood and adolescence, much more bone is deposited than is lost. Up to 90% of peak bone mass is acquired by age 18 in girls and by age 20 in boys.6 That makes healthful eating and physical activity in childhood and adolescence an important step toward prevention in adulthood. This holds true for both boys and girls.
One of the biggest misconceptions about osteoporosis, says Isabel Maples, MEd, RDN, a spokesperson for the Academy of Nutrition and Dietetics (the Academy) based in Washington, D.C., is that it doesn’t affect men, but statistics paint a different picture. It’s true that far more women than men are affected, but according to the NOF, approximately 2 million American men have osteoporosis and about 12 million are at risk. Each year, about 80,000 men will break a hip. A fact that’s likely to come as a shock is that men older than 50 are more likely to break a bone due to osteoporosis than they are to develop prostate cancer.8
According to Maples, the other common misconception is that Black women don’t get osteoporosis. It’s true that white and Asian American women have a greater incidence, and Black women tend to have greater bone density than white women to start, but the NOF estimates that about 5% of Black women older than 50 have osteoporosis and another 35% have low bone mass. Lactose intolerance is common among Black women (about 70%), so many eliminate or limit calcium-rich dairy foods from the diet. Black women also are far less likely to be screened for low bone mass.9
Dietary Recommendations for Prevention
Recommendations for osteoporosis prevention haven’t changed much over the years. Experts still recommend engaging in regular weight-bearing exercise, eg, walking, and getting enough calcium (1,200 mg/day) and vitamin D (600 to 800 IU /day). “About 99% of the body’s calcium stores exist in the skeleton,” Maples says.
Protein makes up about 50% of bone volume and approximately one-third of its mass.10 High-protein diets were once thought to leach calcium from bones but now are thought to play an important role in building bone. Epidemiologic studies show greater protein intake to be beneficial to bone health in adults, especially older adults. Moreover, randomized controlled trials show that protein’s positive effect on bone health is the result of its ability to increase intestinal calcium intake.11,12
Low calcium and vitamin D intakes are associated with increased risk, but it can be difficult for some, especially older patients, to get enough of either in the diet. In these cases, taking a calcium/vitamin D supplement may be the only way to get enough. Dairy foods are the richest sources of calcium and vitamin D (in the case of fortified milk), but there are nondairy milk products fortified with both nutrients, which is important for vegans and some vegetarians. Still, there exists some controversy over how effective calcium and vitamin D are in preventing bone loss, as well as a lack of clarity about other nutrients, such as selenium, magnesium, and vitamin K, and the roles they play in bone formation.
Magnesium is a mineral involved in the laying down of bone, but, according to the American Association of Clinical Endocrinologists, there are no randomized controlled studies showing a benefit of magnesium supplements on bone. Furthermore, “assessing magnesium status is difficult because blood levels of magnesium are not a true representation of magnesium status, since serum levels represent only 0.8% of total body stores,” says Melissa Majumdar, MS, RD, CSOWM, LDN, bariatric coordinator at Emory University Hospital Midtown in Decatur, Georgia, and a spokesperson for the Academy. The Recommended Dietary Allowance (RDA) for magnesium is between 310 and 420 mg per day, depending on age and gender. Good to excellent sources include pumpkin seeds, almonds, spinach, cashews, peanuts, black beans, and edamame.
Several studies support a critical function of vitamin K in improving bone health. Although the vitamin is required for bone building, and several observational and interventional studies have examined the relationship between vitamin K and bone metabolism, there’s no clear evidence on its role in bone formation and prevention of bone loss. The predominant dietary form, phylloquinone (vitamin K1), is found in spinach, broccoli, iceberg lettuce, and soybean and canola oils. Few foods are fortified with vitamin K.13
The mineral selenium also may play an important role. There are antioxidant selenoproteins believed to be vital in maintaining bone health. In fact, plasma selenoprotein concentrations have been found to be associated with better bone mineral density in older women.14 A cross-sectional study from China found among middle-aged and older subjects that those with lower levels of dietary selenium had a higher prevalence of osteoporosis, in a dose-response manner.15 The RDA for selenium is 55 mcg/day. Good to excellent sources of selenium include Brazil nuts, sardines, shrimp, chicken, and macaroni.
Alcohol intake can affect calcium status by reducing its absorption and by inhibiting enzymes in the liver that help convert vitamin D to its active form, but the amount of alcohol required to affect calcium status and whether moderate alcohol consumption is harmful to bone is unknown.16 The 2020–2025 Dietary Guidelines for Americans recommend that if alcohol is consumed, it should be consumed in moderation—limiting intakes to one drink or less per day for women and two drinks or less per day for men. This isn’t an average over several days but rather the amount consumed on any single day. A meta-analysis is underway to determine whether there’s a dose response to alcohol’s effect on bone.17
Studies on the relationship of sodium to osteoporosis are contradictory. High intakes of sodium increase urinary calcium excretion. It has been believed that this suggests a loss of calcium from bone and an increased risk of osteoporosis and fractures. However, a study conducted with data from the Women’s Health Initiative found that sodium intakes greater than 2,300 mg/day weren’t associated with changes in bone mass density at any skeletal site. In fact, higher levels of sodium intake were associated with significantly fewer hip fractures. Calcium intake didn’t alter the association between sodium intake and fractures. Notably, these findings were the result of dietary intake surveys, not a clinical study. But sodium intake of less than 2,300 mg/day is recommended for hypertension and CVD management and prevention, so it remains a prudent dietary recommendation for clients and patients, although perhaps not for osteoporosis prevention.18
Research also suggests a possible association between antioxidant nutrients and osteoporosis prevention. Studies in animals, cell cultures, as well as epidemiologic studies, suggest a positive effect of diets high in vitamin C on bone density.19,20 However, clinical studies are lacking. Polyphenol-rich foods, including olive oil, fruits and vegetables, tea, soy, and even dark chocolate, seem to be beneficial for preventing osteoporosis and its progression, but more research is needed before specific dietary recommendations can be made.21,22
Calcium and Vitamin D Contention
Maintaining an adequate intake of calcium and vitamin D is all but universally recommended for osteoporosis prevention, and supplements often are required to get to an optimal level of intake. However, there are some dissenters. Ian Reid, MD, at the University of Auckland in New Zealand, says the use of calcium supplements arose at a time when there were no other effective interventions for osteoporosis prevention or treatment. Today, there are several prescription therapies. Reid has long stated there’s no clear evidence that either calcium or vitamin D supplementation helps prevent fractures, but such supplementation potentially may have a downside, such as increased risk of kidney stones. He does recommend dietary sources of the two nutrients, such as dairy products. However, it’s possible for vegetarians and vegans to meet recommendations for calcium with judicious planning and the addition of some calcium-fortified foods, including bok choy, broccoli, kale, calcium-set tofu, and calcium-fortified juice.23
In his most recent article on the subject, Reid says calcium supplements produce a 1% increase in bone density in the first year of use but provide no additional benefits thereafter. He also says clinical trials show that vitamin D supplements improve bone density only in those with baseline levels of 25-hydroxyvitamin D of less than 30 nmol/L. According to the National Institutes of Health Office of Dietary Supplements, vitamin D levels below 30 nmol/L are associated with vitamin D deficiency; between 30 and 49 nmol/L is considered inadequate for bone and overall health.
Weight and Bone Loss
While being overweight can strengthen bones, much as weight-bearing exercise does, there are other health risks associated with overweight or obesity. However, weight loss, which can be an effective treatment for type 2 diabetes and hypertension, can aggravate bone loss. These effects appear to be modest following a single weight loss attempt but may persist over the long term and possibly during subsequent weight loss efforts.24
The effect is especially severe in patients who have undergone bariatric surgery. “For over 10 years, I counseled bariatric surgery patients, who are at an increased risk for osteoporosis related to weight loss and risk of vitamin deficiency,” Majumdar says. “We know that weight loss can result in reduced bone mineral density as a result of mechanical unloading, changes in hormones, and loss of lean muscle mass.” Clients and patients who are losing weight or have lost weight should speak with their health care providers about screening for bone loss.
Therapeutics for Osteoporosis
For decades, patients diagnosed with osteoporosis had few options to stop the progression of bone loss or reverse the course of the disease. In fact, until about 24 years ago, there was no effective treatment for osteoporosis aside from the advice to get plenty of calcium and vitamin D and engage in regular, weight-bearing physical activity. The FDA approved the drug Fosamax in 1996, a drug designed to stop bone loss. It’s now available in generic form (alendronate, a bisphosphonate). Medications that increase bone mass, such as Forteo and Prolia, came several years later, as well as the drugs Actonel, Bonivia, and Evista. Even with these medications, the dietary and physical activity recommendations still stand.
Bottom Line
The debilitating nature of osteoporosis doesn’t manifest overnight, but over a period of years without symptoms. “Osteoporosis is called a silent disease for a reason,” Maples says.
Many people experience pain or fractures only once the disease is advanced; that’s why screening is so important. The US Preventive Services Task Force recommends screening for osteoporosis with bone measurement testing in women aged 65 and older and in postmenopausal women younger than 65 who have been determined to be at increased risk.3 “Our health care system is in need of a shift from treatment to prevention,” Majumdar says. That’s especially true for osteoporosis.
Majumdar adds that it’s important to remember that risk factors for osteoporosis often don’t exist independently of other risk factors. In other words, someone whose diet is low in calcium also is likely to be low in other bone-building minerals. And someone whose diet falls short of recommendations for bone-building nutrients also may be more likely to avoid physical activities that benefit bone.
— Densie Webb, PhD, RD, is a freelance writer, editor, and industry consultant based in Austin, Texas.
References
1. NOF releases updated data detailing the prevalence of osteoporosis and low bone mass in the U.S. National Osteoporosis Foundation website. https://www.nof.org/news/54-million-americans-affected-by-osteoporosis-and-low-bone-mass/. Published June 2, 2014.
2. Rosen CJ. The Epidemiology and Pathogenesis of Osteoporosis. South Dartmouth, MA: MDText.com, Inc; 2017.
3. Jin J. Screening for osteoporosis to prevent fractures. JAMA. 2018;319(24):2566.
4. Lo JC, Srinivasan S, Chandra M, et al. Trends in mortality following hip fracture in older women. Am J Manag Care. 2015;21(3):e206-e214.
5. Ranzani OT, Mila C, Kulkarni B, Kinra S, Tonne C. Association of ambient and household air pollution with bone mineral content among adults in peri-urban South India. JAMA Network Open. 2020;3(1):e1918504.
6. Osteoporosis: peak bone mass in women. National Institutes of Health, NIH Osteoporosis and Related Bone Diseases National Resource Center website. https://www.bones.nih.gov/health-info/bone/osteoporosis/bone-mass. Published October 2018.
7. Office of the Surgeon General (US). Bone Health and Osteoporosis: A Report of the Surgeon General. Rockville, MD: Office of the Surgeon General; 2004.
8. Just for men. National Osteoporosis Foundation website. https://www.nof.org/preventing-fractures/general-facts/just-for-men/
9. Osteoporosis and African American women. National Institutes of Health, NIH Osteoporosis and Related Bone Diseases National Resource Center website. https://www.bones.nih.gov/health-info/bone/osteoporosis/background/african-american-women. Updated November 2018.
10. Heaney RP. Effects of protein on the calcium economy. Int Congr Ser. 2007;1297:191-197.
11. Mangano KM, Sahni S, Kerstetter JE. Dietary protein is beneficial to bone health under conditions of adequate calcium intake: an update on clinical research. Curr Opin Clin Nutr Metab Care. 2014;17(1):69-74.
12. Groenendijk I, den Boeft L, van Loon LJC, de Groot L. High versus low dietary protein intake and bone health in older adults: a systematic review and meta-analysis. Comput Struct Biotechnol J. 2019;17:1101-1112.
13. Palermo A, Tuccinardi D, D’Onofrio L, et al. Vitamin K and osteoporosis: myth or reality? Metabolism. 2017;70:57-71.
14. Zhang Z, Zhang J, Xiao J. Selenoproteins and selenium status in bone physiology and pathology. Biochim Biophys Acta. 2014;1840(11):3246-3256.
15. Wang Y, Xie D, Li J, et al. Association between dietary selenium intake and the prevalence of osteoporosis: a cross-sectional study. BMC Musculoskelet Disord. 2019;20(1):585.
16. Hirsch PE, Peng TC. Effects of alcohol on calcium homeostasis and bone. In: Anderson J, Garner S, eds. Calcium and Phosphorus in Health and Disease. Boca Raton, FL: CRC Press; 1996:289-300.
17. Xu B, Chen L, Lee JH. Smoking and alcohol drinking and risk of non-union or delayed union after fractures: a protocol for systematic review and dose-response meta-analysis. Medicine (Baltimore). 2020;99(5):e18744.
18. Carbone L, Johnson KC, Huang Y, et al. Sodium intake and osteoporosis. Findings from the Women’s Health Initiative. J Clin Endocrinol Metab. 2016;101(4):1414-1421.
19. Brzezinska O, Lukasik Z, Makowska J, Walczak K. Role of vitamin C in osteoporosis development and treatment — a literature review. Nutrients. 2020;12(8):2394.
20. Chin KY, Ima-Nirwana S. Vitamin C and bone health: evidence from cell, animal and human studies. Curr Drug Targets. 2018;19(5):439-450.
21. Seem A, Yuan Y, Tou J. Chocolate and chocolate constituents influence bone health and osteoporosis risk. Nutrition. 2019;65:74-84.
22. Chisari E, Shivappa N, Vyas S. Polyphenol-rich foods and osteoporosis. Curr Pharm Des. 2019;25(22):2459-2466.
23. Mangels AR. Bone nutrients for vegetarians. Am J Clin Nutr. 2014;100(Suppl 1):469S-475S.
24. Papageorgiou M, Kerschan-Schindl K, Sathyapalan T, Pietschmann P. Is weight loss harmful for skeletal health in obese older adults? Gerontology. 2020;66(1):2-14.