January 10, 2014

Ghrelin Receptors Regulate Insulin Resistance

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gremlinsOnce again, we thank mice for showing us that high fructose corn syrup does give rise to insulin resistance The revealing study shows how this bottleneck in glucose metabolism occurs and how it can be revamped. The study was published in Nutrition & Diabetes.

Many of us may not realize it but high fructose corn syrup is the most commonly used sweetener in the United States. There has been a gospel of studies done to prove the pros and cons of using HFCS in foods. This study was designed to prove, once and for all, if HFCS is good or not so good.

The 3 groups of mice ate either a regular diet, a high fat diet, or a regular diet with 8% HFCS in drinking water. The HFCS group was intended to mimic the affinity for soft drinks. The metabolic effects of these diets were studied for 10 months.

Adipose tissue macrophages (ATMs) are considered a major factor for obesity and insulin resistance.  There are 2  types of ATMs:  pro-inflammatory and anti-inflammatory. In this study, researchers evaluated the effects of HFCS on ATMs in abdominal fat.

HFCS fed mice had more abdominal tissue inflammation and insulin resistance than the high fat diet mice. These effects were noted regardless of calorie intake or body fat content. HFCS triggered an increase of both proinflammatory ATMs and anti-inflammatory ATMs in abdominal fat.

The anti-inflammatory ATMs were much less abundant in HFCS-fed mice than in high-fat-fed mice. This may be due to the deletion of the ghrelin receptor. Ghrelin is a potent anti-inflammatory.

When the HFCS-fed mice were altered to delete ghrelin receptors, the mice exhibited a controlled response to HFCS fat tissue inflammation and insulin resistance. 

Sad but true, the verdict is that HFCS slows the metabolism, stimulates insulin resistance, and causes pro-inflammatory macrophages to flourish. Deleting our ghrelin-receptors isn’t a viable option. Carbohydrates and proteins restrict the production and release of ghrelin to a greater extent than fats. Definitely don’t feed them after midnight.

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