西方饮食可增加阿尔茨海默病风险
全球目前约有4200万痴呆患者，阿尔茨海默病是其中最常见的类型。在全世界范围内，阿尔茨海默病发生率上升。最重要的危险因素似乎是饮食，特别是代表西方饮食的肉、糖果、高脂肪的乳制品。
2016年7月，《美国营养学院杂志》正式发表旧金山阳光、营养与健康研究中心（SUNARC）的研究报告，通过回顾期刊文献，并利用来自10个国家（巴西、智利、古巴、埃及、印度、蒙古、尼日利亚、韩国、斯里兰卡、美国）的阿尔茨海默病发生率，以及发生率数据之前的5年、10年和15年的饮食营养供给数据，分析了相关饮食习惯与每个国家或地区面临的阿尔茨海默病风险。
结果发现，之前5年肉类或动物产品饮食营养供给（不包括牛奶）与本研究中阿尔茨海默病的发生率相关性最高。美国居民的风险似乎特别高，在美国人均患阿尔茨海默病的风险约为4%，部分原因是西方的饮食结构，这往往包含大量的肉类消费。
J Am Coll Nutr. 2016 Jul;35(5):476-89.
Using Multicountry Ecological and Observational Studies to Determine Dietary Risk Factors for Alzheimer's Disease.
Grant WB.
Sunlight, Nutrition, and Health Research Center, San Francisco, California.
Rates of Alzheimer's disease (AD) are rising worldwide. The most important risk factors seem to be linked to diet. For example, when Japan made the nutrition transition from the traditional Japanese diet to the Western diet, AD rates rose from 1% in 1985 to 7% in 2008. Foods protective against AD include fruits, vegetables, grains, low-fat dairy products, legumes, and fish, whereas risk factors include meat, sweets, and high-fat dairy products. The evidence comes from ecological and observational studies as well as investigations of the mechanisms whereby dietary factors affect risk. The mechanisms linking dietary risk factors to AD are fairly well known and include increased oxidative stress from metal ions such as copper as well as from advanced glycation end products associated with high-temperature cooking, increased homocysteine concentrations, and cholesterol and its effects on amyloid beta, insulin resistance, and obesity. Lower 25-hydroxyvitamin D concentrations also are associated with increased risk of AD. In addition to reviewing the journal literature, a new ecological study was conducted using AD prevalence from 10 countries (Brazil, Chile, Cuba, Egypt, India, Mongolia, Nigeria, Republic of Korea, Sri Lanka, and the United States) along with dietary supply data 5, 10, and 15 years before the prevalence data. Dietary supply of meat or animal products less milk 5 years before AD prevalence had the highest correlations with AD prevalence in this study. Thus, reducing meat consumption could significantly reduce the risk of AD as well as of several cancers, diabetes mellitus type 2, stroke, and, likely, chronic kidney disease.
TEACHING POINTS:
Single-country ecological data can be used to find links between diet and AD because the national diet changes, such as during the nutrition transition to a Western diet.
Multicountry ecological studies can be used to find links between dietary factors and risk of AD.
Prospective observational studies are useful in linking dietary components and patterns to risk of AD.
The most important dietary link to AD appears to be meat consumption, with eggs and high-fat dairy also contributing.
Diets high in grains, fruits, vegetables, and fish are associated with reduced risk of AD, but these factors cannot counter the effects of meat, eggs, and high-fat dairy.
Higher vitamin D status is associated with reduced risk of AD.
KEYWORDS: Alzheimer's disease; Mediterranean diet; Western diet; diet; ecological studies; meat; observational studies; vascular dementia
PMID: 27454859
DOI: 10.1080/07315724.2016.1161566
