Nutritional Regulation of bone

描述(申请人提供)：骨质疏松症和肥胖都是重要的公共卫生问题。减重(Wt)被推荐用于减少肥胖相关的并发症，但会导致绝经后妇女的骨质丢失(即使有足够的钙摄入)。虽然一些研究已经开始解决热量限制(CR)期间饮食结构对代谢参数的影响，但几乎没有人知道它对骨量和质量的作用。这项建议将解决我们在体重损失期间饮食组成方面的几个主要空白，因为它影响骨骼健康。特别是，我们将讨论膳食蛋白质(PRO)水平，以及维生素D(VitD)在钙吸收中的作用。在体重稳定的成年人中有证据表明，较高的膳食PRO增加胰岛素样生长因子-1和钙的吸收，可能有助于更高的骨量和降低骨折风险。相比之下，高PRO摄入量也被证明会增加酸负荷，导致高钙尿和潜在的骨丢失。目前尚不清楚高PRO饮食如何影响CR期间的骨密度或骨质量。此外，在胃旁路手术(GB)后体重严重丢失期间，PRO摄取水平可能特别重要，因为PRO摄取不足(而不是钙和维生素D)，通常遵循可能加剧骨丢失的程序。此外，由于血清甲状旁腺激素(PTH)解释了CR期间观察到的钙吸收减少(400IU维生素D/天)的部分原因，通过饮食增加血清25-羟基维生素D水平可能会减弱血清PTH并增强真正的部分钙吸收(TFCA)。这项建议的目的是：1)研究与标准高碳水化合物(HC)减重饮食相比，高PRO饮食如何影响绝经后女性的骨转换、质量和质量，同时控制正常的钙和维生素D摄入量；2)检查正常和较高PRO摄入量的GB女性；以及3)确定在标准HC减重饮食期间，高维生素D摄入量(1200Lu/d)是否会增加绝经后女性的TFCA。总体而言，对于近%经常节食的美国人来说，预防骨质流失的基本建议是必要的。老年人口将在几十年内翻一番，体重损失是骨丢失、骨折风险和最终死亡的主要决定因素。因此，这些研究对于确定饮食结构如何在老年人群中预防骨质流失是至关重要的，也是及时的。

DESCRIPTION (provided by applicant): Osteoporosis and obesity are both important public health problems. Weight (wt) reduction is recommended to reduce obesity-related complications, but induces bone loss (even with adequate Ca intake) in post- menopausal women. Although several studies have begun to address the effects of diet composition during caloric restriction (CR) on metabolic parameters, virtually nothing is known its role on bone mass and quality. This proposal will address several major gaps in our knowledge concerning dietary composition during wt loss as it impacts bone health. In particular we will address dietary protein (pro) levels, and the role of vitamin D (vit D) in Ca absorption. Evidence in wt-stable adults shows that higher dietary pro increases insulin-like growth factor-1 and Ca absorption and may contribute to a higher bone mass and reduced fracture risk. In contrast, a high pro intake has also been shown to increase the acid load, leading to hypercalciuria, and potential bone loss. It is currently not known how a high pro diet affects bone density or quality during CR. In addition, the level of pro intake may be especially important during severe wt loss after gastric bypass surgery (GB), because of the deficient pro intake (rather than Ca and vit D) that typically follows the procedure that may exacerbate bone loss. Furthermore, because serum parathyroid hormone (PTH) explains part of the reduction in Ca absorption observed during CR (400IU vit D /day), it is possible that increasing serum 25-hydroxy-vit D levels through diet will attenuate serum PTH and enhance true fractional Ca absorption (TFCA). The aims of this proposal are: 1) to examine how a high-pro diet compared to a standard high-carbohydrate (HC) wt loss diet affects bone turnover, mass and quality in post- menopausal women, while controlling for normal Ca and vit D intake; 2) to examine bone with usual and higher pro intake during severe wt loss in women with GB; and 3) to determine if a high vit D intake (1200 lU/d) can increase TFCA in postmenopausal women during a standard HC wt-loss diet. Overall, rationale recommendations for the prevention of bone loss are needed for nearly % of the US population that is regularly dieting. The older population is going to double in only a few decades, and wt loss is a major determinant of bone loss, fracture risk, and ultimately mortality. Thus, the importance of these studies for identifying how diet composition can prevent bone loss in the older population is both critical and timely.