Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, P.O. Box: 13145158, Tehran, Iran.
Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran.
Nutr J. 2019 Dec 12;18(1):86. doi: 10.1186/s12937-019-0511-x.
Previous studies on the link between macronutrients and breast cancer have mostly focused on individual macronutrients rather than their combination. This study investigates the association between adherence to a low carbohydrate diet and odds of breast cancer among women.
This hospital-based case-control study was carried out on 412 women with pathologically confirmed breast cancer within the past year and 456 apparently healthy controls that were matched in terms of age and residential place. Dietary data was collected using a 168-item validated FFQ. Participants were classified in terms of quintiles of percentages of energy intake from carbohydrates, proteins, and fats. Then, individuals in the highest quintile of fat and protein intake were given a score of 5 and those in the lowest quintile of these macronutrients were given a score of 1. Participants in the other quintiles of these macronutrients were given the corresponding score. In terms of carbohydrate intake, those in the highest quintile received a score of 1 and those in the lowest quintile received 5. The scores were then summed up to calculate the total low carbohydrate diet (LCD) score, which varied from 3 to 15. A higher score meant greater adherence to a low carbohydrate diet.
The mean age of study participants was 45.2 y and mean BMI was 28.4 kg/m. Mean LCD score of participants was 8.9 ± 2.5 (8.9 ± 2.6 in cases and 9.0 ± 2.5 in controls). Although no significant association was observed between adherence to the LCD score and odds of breast cancer in the study population, a trend toward significant positive association was seen between consumption of LCD and odds of breast cancer in postmenopausal women; after controlling for several potential confounders, individuals in the third quartile of LCD score were 1.94 times more likely to have breast cancer than those in the lowest quartile (95% CI: 1.00, 3.76). This association strengthened after controlling for dietary variables (2.50; 1.18-5.32). Even after further adjustment for BMI, this association remained significant (2.64, 1.23-5.67). No significant relationship was observed in premenopausal women, either before or after controlling for confounders.
Adherence to LCD may be associated with increased odds of breast cancer in postmenopausal women. Prospective cohort studies are needed to confirm these findings.
先前关于宏量营养素与乳腺癌之间关联的研究大多集中于单个宏量营养素，而不是它们的组合。本研究旨在调查低脂碳水化合物饮食与女性乳腺癌发病风险之间的关系。
这是一项基于医院的病例对照研究，共纳入 412 名在过去一年中经病理证实的乳腺癌患者（病例组）和 456 名年龄和居住地点相匹配的健康对照者（对照组）。采用经过验证的 168 项食物频数问卷收集膳食数据。根据碳水化合物、蛋白质和脂肪的能量摄入百分比，将参与者分为五分位数组。然后，将脂肪和蛋白质摄入量最高五分位数的个体得分为 5，将这些宏量营养素摄入量最低五分位数的个体得分为 1。其他五分位数的个体则得相应的分数。对于碳水化合物摄入量，将最高五分位数的个体得分为 1，最低五分位数的个体得分为 5。然后将这些分数相加，计算出总的低脂碳水化合物饮食（LCD）评分，范围为 3 至 15。分数越高表示对低脂碳水化合物饮食的依从性越高。
研究参与者的平均年龄为 45.2 岁，平均 BMI 为 28.4kg/m²。参与者的平均 LCD 评分为 8.9±2.5（病例组为 8.9±2.6，对照组为 9.0±2.5）。尽管在研究人群中未观察到 LCD 评分与乳腺癌发病风险之间存在显著关联，但在绝经后妇女中，LCD 摄入量与乳腺癌发病风险之间存在显著正相关的趋势；在校正了几个潜在混杂因素后，LCD 评分处于第三四分位数的个体发生乳腺癌的风险是处于最低四分位数的个体的 1.94 倍（95%CI：1.00，3.76）。在校正饮食变量后，这种关联增强（2.50；1.18-5.32）。即使进一步调整 BMI，这种关联仍然显著（2.64，1.23-5.67）。在未绝经妇女中，无论是在调整混杂因素之前还是之后，均未观察到这种关联。
低脂碳水化合物饮食的依从性可能与绝经后妇女乳腺癌发病风险增加有关。需要前瞻性队列研究来证实这些发现。
