Thursday, April 14, 2011

Research Update: Sleep and snacking and disturbing news about omega 3’s

Dietary omega-3 fatty acids and fish consumption and risk of type 2 diabetes
American Journal of Clinical Nutrition 2011 93:143-50

This study looked at the association between omega 3 intake and risk of type 2 diabetes. Over 36,300 women from the Women’s Health Study were followed for 16 years and during this time there were 2,370 new cases of type 2 diabetes.  Women who consumed the most marine based omega 3’s (.43 grams a day) had a 44% increased risk of type 2 diabetes compared to women who consumed the least (.07 grams per day).  A similar increased risk was found for women who consumed the most fish (4 servings per week) compared to women who consumed the least (1/2 serving per week).

Take Home Message:  This is a very significant finding.  People are going nuts about omega 3 supplementation.  Omega 3’s have been shown to have extremely beneficial effects on risk of heart disease, which is great, but here is evidence that going overboard has the potential to hurt you.  This is not the first study to show an adverse effect of high amounts of omega 3.  Several other well designed studies have shown higher glucose levels and decreased insulin sensitivity in type 2 diabetic patients with large doses of omega 3 fatty acids.   Get your omega 3’s through your diet, as nature intended, by eating a variety of seafood meals 2-3 times per week.  My clients and those who have read my book know that I am not a fan of supplementation in general.  Too many times concentrated nutrients in large dose supplement form create unexpected consequences in humans.  Get your nutrients through your diet and you’ll have nothing to worry about.

Sleep curtailment is accompanied by increased intake of calories from snacks
American Journal of Clinical Nutrition 2009; 89:126-33

This is a beautifully designed little study on sleep deprivation and subsequent energy intake.  Eleven healthy subjects slept in a sleep lab for 14 days on two separate occasions.  The sleep lab is a controlled environment where physical activity, sleep and energy intake can be strictly monitored.  The subjects were given unlimited access to as much food as they wanted.  On the first 14 day visit they were restricted to 5.5 hours of sleep a night. On the second 14 day visit, they were allowed to sleep 8.5 hours per night.  Besides the amount of sleep, everything else about the two interventions was identical.  The amount of food they ate throughout the two interventions was measured and compared.  When the subjects slept only 5.5 hours a night they consumed 297 more calories per day!

Take Home Message: Get your sleep!  That rate of caloric consumption would result in a weight gain of 1 pound every 12 days.   Several studies have shown that a lack of sleep increases ghrelin levels (a hormone that influences appetite) and decreases leptin levels (a hormone that influences metabolism).  This must not be the whole story because in this study there was no difference in leptin and ghrelin levels.   More research is needed to elucidate the mechanisms at play here but the message is clear: Get your sleep.


Larry said...

Thanks for referencing these studies Dr. Halton.
In regards to the fish study, I'm surprised becasue I believe that omega-3 also lowers trigylcerides, which is also a risk factor for diabetes. Does the study report high GI carb intake as well and BMI, and were there no correlations to these? Thank you!

Dr. Thomas Halton said...

Thanks for the comment Roseman and sorry for the late reply, I've been traveling a bit lately but I'm back! I was also surprised by these findings. It seems the mechansim may have something to do with increased fasting glucose concentration but I don't think we know how omega 3's raise fasting glucose. For sure, more research is needed here. The study controlled for both body mass index and glycemic index so theoretically the effect of these variables was eliminated in the modelling.