儿童饮食可能影响1型糖尿病损伤

SEARCH 研究分析显示，Omega-3脂肪酸和亮氨酸可能有助于保护新诊断的1型糖尿病儿童胰岛β细胞功能。较高基线水平的血浆omega-3s二十碳五烯酸、二 十二碳六烯酸(EPA 和DHA, 在鱼类中常见)和亮氨酸（来自肉、蛋和大豆）浓度与更高水平的C肽浓度相关，在这个纵向队列观察研究中C肽是用来表示2年后平均胰岛素产生水平的指标。来 自北卡罗来那大学的Elizabeth Mayer-Davis博士和她的同事说：“这代表了一个改善1型糖尿病预后的一个新的研究方向。”

该研究在DiabetesCare杂志线上发表，同时发布在美国糖尿病协会的会议上。该研究在随访期间还发现了一件没有预料到的事情，就是较高的维生素D基 线水平同较低的胰岛β细胞功能相关。Mayer-Davis向与会者说：“我们绞尽了脑汁，但仍不能合理的解释这一现象。我们不能从生物学角度来合理解释 为什么维生素D是有害的，所以我们认为我们得到的这个结果很可能是一个偶然的结果。”同样来自北卡罗来那大学、没有参加这项研究工作的Sue Kirkman医生对此评论道，以往的研究暗示维生素D可能是有保护性作用的，因为较高的维生素D水平和阳光充足的地区，1型糖尿病发生率也较低。 Kirkman发出警告，父母和临床医生不应该按照这个结论行事，应等待其它队列观察研究或是对照研究中是否能够重复这个结论。

来自波士顿乔斯琳糖尿病中心的Lori Laffel评论：“如果能够找到保护胰岛β细胞功能的办法，那将是很伟大的一件事。”以往的研究表明，保护残留的β细胞功能同更好的血糖控制、较少发生 低血糖以及较少发生微血管病有关。她对 MedPage Today说：“鼓励健康的饮食是可行的。鼓励健康饮食对于患有1型糖尿病的患者和他们的家庭来说一直是很重要的。每个人都应该健康饮食。”她同意 Kirkman医生的意见，亮氨酸或鱼油的补充是否可以做为一种干预措施，应做进一步的研究。

SEARCH研究包括1316名儿童，在 2002—2005期间，诊断患有自身抗体阳性的1型糖尿病，全部在20岁前诊断（平均诊断年龄11岁）。基线水平，平均疾病持续时间是10个月，29% 已经完全丧失胰岛β细胞功能，丧失胰岛β细胞功能定义为空腹C肽水平等于或低于0.23 ng/mL。在随访中至少重复检查了1次C肽水平的患者共有656人，他们是SEARCH营养辅助研究的主要目标人群，在随访期间58%的病人完全丧失胰 岛?细胞功能。C肽水平平均下降57%。在进行了人口统计数据、疾病相关因子、其它混杂因子的调整后，前瞻性分析结果显示血浆C肽水平同下列指标基线水平相关：血浆EPA (P=0.02)、血浆EPA和DHA (P=0.03)、亮氨酸摄入(P=0.03)

根据结果，研究者计算出如果比基线血浆EPA或是 EPA+ DHA水平高出一个标准差，就会在随访中发现C肽水平有9%的提高。基线亮氨酸摄入水平高出一个标准差，就会在随访中发现C肽水平有5.7%的提高。而血浆维生素D水平和C肽水平呈负相关，基线维生素D水平高出一个标准差，就会在随访中发现C肽水平有12.6%的降低。母乳喂养没有显示出明显的保护性作用 (P=0.06)，固体食物、牛奶或是配方食物也都没有任何影响。没有任何因子与人类白细胞共同抗原基因型发生相关作用。

这项研究的不足包括研究中的饮食数据都是来自病人自己的报告，虽然也进行了血浆水平的客观测量。此外一个不足就是研究中更多使用的指标是空腹C肽水平，而不是食物刺激后的C肽水平。

（丁香园：月下荷花）

ADA: Kids' Diet May Impact T1D Damage

Omega-3 fatty acids and the amino acid leucine may help preserve beta-cell function in children with recently-diagnosed type 1 diabetes, a SEARCH study analysis suggested.

Higher baseline plasma levels of the omega-3s eicosapentaenoic acid and docosahexaenoic acid (EPA and DHA, typically found in fish) and leucine (from meat, eggs, and soy) correlated with higher levels of C-peptide concentration as a measure of insulin production an average of 2 years later in the longitudinal observational cohort.

"This represents a new direction for research to improve prognosis for type 1 diabetes," Elizabeth Mayer-Davis, MSPH, PhD, RD, of the University of North Carolina at Chapel Hill, and colleagues suggested.

However, higher vitamin D levels at baseline unexpectedly correlated with lower beta-cell function at follow-up, the researchers reported online in Diabetes Care in conjunction with a presentation here at the American Diabetes Association meeting.

"We have wracked our brains over that, we don't have an explanation," Mayer-Davis told attendees at the session. "We can't think of any reason biologically why vitamin D would be deleterious and so we assumed the result we got was most likely due to chance."

Prior studies suggested vitamin D might be protective, with lower type 1 diabetes incidence with higher vitamin D levels and in sunnier climes, commented Sue Kirkman, MD, also of the University of North Carolina, but uninvolved in the study.

Parents and clinicians shouldn't act on the results until replicated in other observational cohorts and possibly controlled trials, Kirkman cautioned.

"It would be great to find ways to preserve beta-cell function," commented Lori Laffel, MD, MPH, of the Joslin Diabetes Center in Boston.

Preservation of residual beta-cell function has been associated with better glucose control and less risk of hypoglycemia or microvascular complications in prior studies.

"It is probably worthwhile trying to encourage a healthy diet," she told MedPage Today. "It's always important to encourage a healthy diet for patients and families with type 1 diabetes. Everyone should be eating a healthful diet."

But she agreed with Kirkman in calling for further study before leucine or fish oil supplements could be considered as interventions.

The SEARCH for Diabetes in Youth study included 1,316 kids with autoantibody-positive type 1 diabetes diagnosed before age 20 (mean 11) during the years 2002 through 2005.

At baseline, the average disease duration was 10 months and 29% had already lost all beta-cell function, as defined by a fasting C-peptide (FCP) level of 0.23 ng/mL or less.

Among the remaining 656 with at least one subsequent C-peptide measurement, who were the subject of the SEARCH Nutrition Ancillary Study, 58% had lost beta-cell function by follow-up. The average change was a decrease by 57%.

After adjustment for demographics, disease-related factors, and other confounders, prospective analyses showed correlations of plasma C-peptide concentration at follow-up with baseline levels of:
 

• Plasma EPA (P=0.02)
• Plasma EPA plus DHA (P=0.03)
• Leucine intake (P=0.03)

For context, the researchers calculated that a one standard deviation higher baseline plasma EPA level or EPA plus DHA level correlated with a 9% higher C-peptide level at follow-up.

A one standard deviation higher leucine intake was associated with 5.7% higher C-peptide level at follow-up.

For the inverse link between plasma vitamin D and C-peptide levels (P=0.002), a one standard deviation higher level was associated with a 12.6% lower FCP at follow-up.

Breast feeding showed a nonsignificant trend for being protective (P=0.06), but age at introduction of solid foods, dairy, or formula showed no impact.

None of the factors interacted with human leukocyte antigen (HLA) genotype.

Limitations included the self-reported diet data, although plasma levels were objectively measured, and fasting rather than food-stimulated C-peptide was measured.

原文链接：http://www.medpagetoday.com/MeetingCoverage/ADA/4004

编辑： belinda_1231    来源：丁香园