BONE HEALTH BASICS. Promoting Healthy Bones: Sorting Out the Science. Learning Objectives. Guest Speaker

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1 Copyright 11 by the Preventive Cardiovascular Nurses Association Promoting Healthy Bones: Sorting Out the Science Guest Speaker Robert P. Heaney, MD, FACP, FASN Professor and Professor of Medicine Creighton University Learning Objectives Cite two major factors contributing to poor bone health. Discuss the synergy between nutrition and exercise in promoting bone health. Explain the inadequacy of taking a mono-nutrient approach to bone health, using the impact of protein intake on calcium balance as an example. Discuss clinical research findings related to the impact of caffeine, phosphorus/phosphoric acid, and carbonation on calcium balance and bone health. BONE HEALTH BASICS

2 HEALTHY BONES Bone health means that the skeleton is strong enough to withstand the strains of everyday living Bone strength depends upon bone mass and bone architecture The principal disorder of bone strength is osteoporosis, defined as a condition of skeletal weakness characterized by a decrease in bone mass & by micro-architectural deterioration of bone tissue HEALTHY BONES Maintenance of healthy bones has two basic requirements: Mechanical loading (i.e. work) Adequate nutrition calcium phosphorus vitamin D protein potassium MECHANICAL LOADING One reason bone health has deteriorated over the past 5 years is reduced physical work. Exercise (mechanical loading) and nutrition work together to promote bone health neither is adequate alone. A high calcium intake without exercise does not improve bone mineral density. Exercise without extra calcium also does not improve bone mineral density.

3 EXAMPLE: SYNERGY OF DIET & EXERCISE 8 6 Low Ca High Ca The key: Ca PLUS exercise BMD CHANGE (%) 4 Exercise did nothing without Ca Ca did nothing without exercise - Sedentary Exercise Specker, J Bone Miner Res. 1996;11: A CAUTIONARY MESSAGE bone, like muscle, was meant to sustain mechanical work if we don t do physical work, we won t have strong bones there s no magic bullet or wonder food that allows us to escape that linkage moreover, there s no point in demonizing particular foods as if they were the sole causes of weak bones total diet counts, and must be emphasized, but we can t forget exercise ADEQUATE NUTRITION Another reason bone health has deteriorated over the past 5 years is reduced effective inputs of calcium and vitamin D in particular but also of all key nutrients. Nutrient inputs can be reduced by: Decreased intake Decreased absorption Decreased retention

4 EXAMPLE: CALCIUM INTAKE With primitive diets (that consisted mainly of low calorie plant foods) high energy needs virtually ensured adequate Ca intake Energy needs are significantly lower today and people tend to meet much of their needs with energy-dense and sometimes nutrient-poor foods. The result: Many people are not getting enough Ca, potassium, and high-quality protein in their diets. TAKING A MONO-NUTRIENT NUTRIENT APPROACH TO BONE HEALTH IS USUALLY WRONG Bone, like all tissues, needs ALL nutrients. Nutrients do not work independently in the body they work in teams. Diets low in one nutrient tend to be low in many nutrients. Obtaining adequate amounts of all the nutrients needed by bones requires an overall healthy diet. Let s look at an example. EXAMPLE: WHY TAKING A MONO-NUTRIENT NUTRIENT APPROACH IS USUALLY WRONG CHANGE AT 3 YEARS (percent) 1-1 Femoral Neck BMD Impact of Ca + Vit D Supplementation on BMD Although this study clearly showed a benefit with supplementation, a further analysis of the data shows the benefit was limited to women who also had a high protein intake. - Calcium Placebo Dawson-Hughes et al., NEJM 1997:337:67-6

5 BMD INCREASES WERE LIMITED TO WOMEN WITH HIGH PROTEIN INTAKES CHANGE AT 3 YEARS (percent) Femoral Neck BMD Calcium Placebo Calcium Group + D group Only only Low Medium High Protein Intake Tertile Dawson-Hughes et al., NEJM 1997:337:67-6 Dawson-Hughes et al., AJCN :75:773-9 IMPACT Of PROTEIN INTAKE ON Ca BALANCE Is there a plausible biological explanation? Yes. Bone is 5% protein by volume. It is one of the most protein-rich tissues in the body When bone is remodeled (as is going on continuously), its component Ca and P can be recycled, but most of its protein cannot be reused Bone rebuilding, even in adults, requires a fresh supply of dietary protein. IMPACT Of PROTEIN INTAKE ON Ca BALANCE Was this study of Dawson-Hughes et al. an isolated finding or does the impact of protein intake on calcium retention (BMD) show up in other studies as well?

6 Ca INTAKE & Ca BALANCE: EFFECT OF PROTEIN INTAKE CALCIUM BALANCE (mg/d) Ca balance in these 644 studies is seen 1 to be positively correlated with Ca intake. This means that Ca retention The depends next slide upon how shows much results Ca one of a - 1 reanalysis ingests. of These these data data, played evaluating a major role - specifically in the 1994 NIH whether recommendations protein intake for Ca affects intake Ca in women retention. CALCIUM INTAKE (mg/d) Heaney RP. In: Nutritional Aspects of Osteoporosis 6. Ca INTAKE & Ca BALANCE: EFFECT OF PROTEIN INTAKE.7 When protein intake was greater than 6.8 g/d, Ca intake & retention were significantly positively correlated. SLOPE OF Ca BALANCE ON CALCIUM INTAKE.6 When protein intake was less than 6.8 g/d, there was no correlation between Ca intake & retention < 6 g/d > 6 g/d PROTEIN INTAKE Heaney RP. In: Nutritional Aspects of Osteoporosis 6. NUTRIENT SYNERGY Calcium and protein intakes interact constructively on bone, as long as intakes for each are adequate.

7 OSTEOPOROSIS a multifactorial disorder, involving heredity estrogen deficiency immobility nutritional inadequacy especially Ca, Vitamin D, & protein corticosteroids alcohol other in varying combinations OSTEOPOROSIS a multifactorial disorder, involving heredity estrogen deficiency immobility nutritional inadequacy especially Ca, Vitamin D, & protein corticosteroids Ca is a matter of major alcohol concern. other What factors may influence Ca absorption in varying combinations and retention? Bone Health and Osteoporosis A Report of the Surgeon General Calcium has been singled out as a major public health concern today because it is critically important to bone health and the average American consumes levels of calcium that are far below the amount recommended for optimal bone health. October 14, 4

8 Bone Health and Osteoporosis A Report of the Surgeon General Calcium has been singled out as a major public health concern today because it is critically important to bone health and the average American consumes levels of calcium that are far below the amount recommended for optimal bone health. October 14, 4 CALCIUM, VIT D, & FRACTURE* CUMULATIVE PROBABILITY OF HIP FRACTURE.9 placebo.6 Ca + D MONTH CHANGE IN BMD AT THE HIP(%) Ca + Vit D Placebo 4-17 mg/d mg/d TIME (months) *after Chapuy et al., (199) NEJM 37:1637 CALCIUM, VIT D, & FRACTURE 176 men; 13 women ages > 65 treatment: Ca 5 mg + Vit D 7 iu FIRST NON-VERTEBRAL FRACTURE (Cumulative incidence %) placebo 55% Ca + Vit D 1 3 TIME ON STUDY (months) Dawson-Hughes et al., NEJM 1997:337:67-6

9 REMODELING & FRAGILITY AGE, ESTROGEN, & REMODELING* remodeling rate doubles across menopause triples by age 65 change due to estrogen withdrawal the increase in fragility in post-menopausal women is due in part to this change, which has nothing to do with bone mass, but much to do with adequate Ca intake CALCIUM, VIT D, & FRACTURE 176 men; 13 women ages > 65 treatment: Ca 5 mg + Vit D 7 iu FIRST NON-VERTEBRAL FRACTURE (Cumulative incidence %) placebo 55% Ca + Vit D 1 3 TIME ON STUDY (months) Dawson-Hughes et al., NEJM 1997:337:67-6

10 CALCIUM, VIT D, & FRACTURE Fracture risk reduction begins immediately before appreciable change in bone mass can occur. The most likely change that explains this timing is reduced remodeling. FIRST NON-VERTEBRAL FRACTURE (Cumulative incidence %) placebo 55% Ca + Vit D 1 3 TIME ON STUDY (months) Dawson-Hughes et al., NEJM 1997:337:67-6 ANTIRESORTIVES & FRACTURE RISK* 5 women in FIT contrasted women in active Odds Ratio Fracture 1 treatment arm who had BMD (i.e., losers) with BMD > (i.e., gainers) Odds Ratio for incident vertebral fracture computed relative to placebo-treated women with same BMD response % 53% spine hip losers gainers *Chapurlat et al. (5) OI 16: ANTIRESORTIVES & FRACTURE RISK* Conclusion: it was the reduction in remodeling produced by alendronate, not the change in BMD,that was responsible for the fracture reduction Odds Ratio Fracture 1 losers gainers.8 6% 53%.6.4. spine hip *Chapurlat et al. (5) OI 16:84 848

11 INTERPRETATION similar responses occur with Ca, SERMs, estrogen, and all anti-resorptives it is not the change in BMD, but the reduction in remodeling, that is most probably responsible for the reduced fracture risk FREQUENTLY ASKED QUESTIONS What about carbonated beverages? Do they harm the skeleton? Do carbonated beverages and colas in particular leach Ca out of bones? BACKGROUND: CARBONATED BEVERAGES AND BONE HEALTH Several epidemiological studies report negative associations between carbonated beverage consumption and various measures of bone health, such as bone mineral density and fractures.

12 COLAS AND BONE* 1413 women in Framingham Osteoporosis study Intake assessed by FFQ no difference at the spine Femoral Neck BMD (g/cm ) * *. <1 <3 <7 >7 Colas Consumption (servings/wk) HERE ARE THE ANSWERS phosphorus & phosphoric acid do not adversely affect Ca balance* caffeine does not adversely affect Ca balance* carbonation does not adversely affect Ca balance* however, anything that displaces milk from the diet will adversely affect Ca balance *Heaney & Rafferty AJCN 1;74:343 TRENDS IN MILK AND CARBONATED BEVERAGE CONSUMPTION GALLONS PER PERSON PER YEAR Milk Carbonated Beverages YEAR Getting enough of the essential bone nutrients is difficult without milk. But there is room in a healthy diet for both beverages.

13 Bone Health and Osteoporosis A Report of the Surgeon General... the gap between what we know and its application in the community remains large and needs to be closed. October 14, 4 A WORD ABOUT FORTIFICATION To offset the reduced intake of essential nutrients in the modern diet, some sort of fortification is most likely necessary. e.g., folate, niacin, fluoride, vitamin D, iodine, etc. However, the fortificants must be in a form the body can assimilate. Although fortification can help improve intake of specific nutrients of concern, consumers must understand the importance of an overalladequate diet and physical exercise in maintaining bone health. SUMMARY Bone health requires both adequate totalnutrition and physical work (weight-bearing exercise). Taking a mono-nutrient approach to bone health is usually wrong. The key components of carbonated beverages (caffeine, phosphoric acid, citric acid, carbonation) do not negatively affect Ca balance.

14 SUMMARY Declining milk consumption is of great concern because it is difficult to get enough key bone nutrients from the diet without it. But a healthy diet has room for both milk and carbonated beverages. Given current calorie intakes, some sort of fortification is most likely necessary, but the fortificants must be in a form the body can assimilate. Question & Answer Use the chat box located on the left side of your screen to ask a question Copyright 11 by the Preventive Cardiovascular Nurses Association