Instituto de Efectividad Clínica y Sanitaria (IECS-CONICET), Buenos Aires, Argentina.
Argentine Cochrane Centre, Institute for Clinical Effectiveness and Health Policy (IECS-CONICET), Buenos Aires, Argentina.
Cochrane Database Syst Rev. 2024 May 9;5(5):CD012268. doi: 10.1002/14651858.CD012268.pub2.
Obesity is a major health problem worldwide as it can lead to high blood pressure, heart disease, stroke, diabetes, and insulin resistance. The prevalence of overweight and obesity is increasing worldwide across different age groups. There is evidence of an inverse relationship between calcium intake and body weight. The clinical relevance of a small reduction in body weight has been questioned. However, at a population level, a small effect could mitigate the observed global trends.
To assess the effects of calcium supplementation on weight loss in individuals living with overweight or obesity.
We searched CENTRAL, MEDLINE, Embase, LILACS (Latin American and Caribbean Health Science Information database), and two clinical trials registries. The date of the last search of all databases (except Embase) was 10 May 2023. No language restrictions were applied.
We included randomised controlled trials evaluating the effect of calcium in participants with overweight or obesity of any age or gender. We excluded studies in participants with absorption problems. We included studies of any dose with a minimum duration of two months. We included the following comparisons: calcium supplementation versus placebo, calcium-fortified food or beverage versus placebo, or calcium-fortified food or beverage versus non-calcium-fortified food or beverage. We excluded studies that evaluated the effect of calcium and vitamin D or mixed minerals compared to placebo.
We used standard methodological procedures expected by Cochrane. Our primary outcomes were body weight, health-related quality of life, and adverse events. Our secondary outcomes were anthropometric measures other than body weight, all-cause mortality, and morbidity.
We found 18 studies that evaluated the effect of calcium compared to placebo or control, with a total of 1873 randomised participants (950 participants in the calcium supplementation groups and 923 in the control groups). All included studies gave oral calcium supplementation as the intervention. We did not find any studies evaluating calcium-fortified foods. We excluded 38 studies, identified four ongoing studies, and listed one study as 'awaiting classification'. Sixteen studies compared calcium supplementation to placebo; two studies compared different doses of calcium supplementation. Doses ranged from very low (0.162 g of calcium/day) to high (1.5 g of calcium/day). Most studies were performed in the USA and Iran, lasted less than six months, and included only women. Low-certainty evidence suggests that calcium supplementation compared to placebo or control may result in little to no difference in body weight (mean difference (MD) -0.15 kg, 95% confidence interval (CI) -0.55 to 0.24; P = 0.45, I = 46%; 17 studies, 1317 participants; low-certainty evidence). We downgraded the certainty of the evidence by two levels for risk of bias and heterogeneity. None of the included studies reported health-related quality of life, all-cause mortality, or morbidity/complications as outcomes. Only five studies assessed or reported adverse events. Low-certainty evidence suggests a low frequency of adverse events, with no clear difference between intervention and control groups. Moderate-certainty evidence shows that calcium supplementation compared to placebo or control probably results in a small reduction in body mass index (BMI) (MD -0.18 kg/m,95% CI -0.22 to -0.13; P < 0.001, I = 0%; 9 studies, 731 participants) and waist circumference (MD -0.51 cm, 95% CI -0.72 to -0.29; P < 0.001, I = 0%; 6 studies, 273 participants). Low-certainty evidence suggests that calcium supplementation compared to placebo or control may result in a small reduction in body fat mass (MD -0.34 kg, 95% CI -0.73 to 0.05; P < 0.001, I = 97%; 12 studies, 812 participants).
AUTHORS' CONCLUSIONS: Calcium supplementation for eight weeks to 24 months may result in little to no difference in body weight in people with overweight or obesity. The current evidence is of low certainty, due to concerns regarding risk of bias and statistical heterogeneity. We found that the degree of heterogeneity might be partly explained by calcium dosage, the presence or absence of a co-intervention, and whether an intention-to-treat analysis was pursued. While our analyses suggest that calcium supplementation may result in a small reduction in BMI, waist circumference, and fat mass, this evidence is of low to moderate certainty. Future studies could investigate the effect of calcium supplementation on lean body mass to explore if there is a change in body composition.
肥胖是一个全球性的主要健康问题，因为它会导致高血压、心脏病、中风、糖尿病和胰岛素抵抗。超重和肥胖的患病率在全球不同年龄组中都在增加。有证据表明，钙的摄入量与体重呈负相关。临床对体重减轻的微小影响的相关性一直存在质疑。然而，从人群水平来看，这种微小的效果可能会减轻观察到的全球趋势。
评估钙补充剂对超重或肥胖个体体重减轻的影响。
我们检索了 CENTRAL、MEDLINE、Embase、LILACS（拉丁美洲和加勒比健康科学信息数据库）和两个临床试验注册库。除了 Embase 之外，所有数据库的最后一次检索日期均为 2023 年 5 月 10 日。未对语言进行限制。
我们纳入了评估超重或肥胖的任何年龄或性别的参与者中钙的效果的随机对照试验。我们排除了有吸收问题的参与者的研究。我们纳入了至少持续两个月的任何剂量的研究。我们纳入了以下比较：钙补充剂与安慰剂、钙强化食品或饮料与安慰剂或钙强化食品或饮料与非钙强化食品或饮料。我们排除了评估钙和维生素 D 或混合矿物质与安慰剂相比的效果的研究。
我们使用了 Cochrane 预期的标准方法学程序。我们的主要结局是体重、健康相关生活质量和不良事件。我们的次要结局是体重以外的人体测量指标、全因死亡率和发病率。
我们发现了 18 项研究，评估了钙与安慰剂或对照相比的效果，共有 1873 名随机参与者（钙补充组 950 名参与者，对照组 923 名参与者）。所有纳入的研究均给予口服钙补充剂作为干预措施。我们没有发现任何评估钙强化食品的研究。我们排除了 38 项研究，确定了 4 项正在进行的研究，并将 1 项研究列为“待分类”。16 项研究比较了钙补充剂与安慰剂；两项研究比较了不同剂量的钙补充剂。剂量范围从非常低（每天 0.162 克钙）到高（每天 1.5 克钙）。大多数研究在美国和伊朗进行，持续时间不到六个月，且仅包括女性。低质量证据表明，与安慰剂或对照相比，钙补充剂可能对体重几乎没有影响（平均差值 -0.15 千克，95%置信区间 -0.55 至 0.24；P = 0.45，I = 46%；17 项研究，1317 名参与者；低质量证据）。我们将证据的确定性降低了两个级别，原因是存在偏倚和异质性的风险。纳入的研究均未报告健康相关生活质量、全因死亡率或发病率/并发症。只有 5 项研究评估或报告了不良事件。低质量证据表明，不良事件的发生频率较低，干预组和对照组之间没有明显差异。中等质量证据表明，与安慰剂或对照相比，钙补充剂可能会使体重指数（BMI）略有下降（MD -0.18 千克/米，95%置信区间 -0.22 至 -0.13；P < 0.001，I = 0%；9 项研究，731 名参与者）和腰围（MD -0.51 厘米，95%置信区间 -0.72 至 -0.29；P < 0.001，I = 0%；6 项研究，273 名参与者）。低质量证据表明，与安慰剂或对照相比，钙补充剂可能会使体脂肪量略有减少（MD -0.34 千克，95%置信区间 -0.73 至 0.05；P < 0.001，I = 97%；12 项研究，812 名参与者）。
钙补充剂持续 8 周至 24 个月可能对超重或肥胖者的体重几乎没有影响。由于存在偏倚和统计异质性的问题，目前的证据质量较低。我们发现，异质性的程度可能部分归因于钙剂量、是否存在联合干预以及是否进行意向治疗分析。虽然我们的分析表明，钙补充剂可能会使 BMI、腰围和体脂肪量略有减少，但这种证据的确定性较低至中等。未来的研究可以探讨钙补充剂对瘦体重的影响，以探讨是否会改变身体成分。
