Modification of high saturated fat diet with n‐3 polyunsaturated fat improves glucose intolerance and vascular dysfunction

Sep 7, 2012Diabetes, obesity & metabolism

Adding omega-3 fats to a high saturated fat diet improves blood sugar control and blood vessel function

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Abstract

Dietary replacement of saturated fats with n-3 PUFA-enriched menhaden oil significantly improved glucose tolerance and vascular function in mice.

Mice on a high saturated fat diet showed elevated body weights and abnormal glucose tolerance after 12 weeks.
Substituting half of the saturated fat with n-3 PUFA-enriched menhaden oil restored basal glucose levels and improved insulin signaling.
The improvements in glucose tolerance and insulin signaling were not observed with n-6 PUFA-enriched safflower oil or MUFA-enriched olive oil.
Vascular dysfunction indicated by reduced dilation to acetylcholine was fully restored in mice fed menhaden oil compared to normal diet.
The menhaden oil diet also resulted in reduced constriction to phenylephrine, indicating improved vascular reactivity.

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AIMS: The ability of dietary enrichment with monounsaturated fatty acid (MUFA), n-3 or n-6 polyunsaturated fatty acids (PUFAs) to reverse glucose intolerance and vascular dysfunction resulting from excessive dietary saturated fatty acids is not resolved. We hypothesized that partial replacement of dietary saturated fats with n-3 PUFA-enriched menhaden oil (MO) would provide greater improvement in glucose tolerance and vascular function compared to n-6 enriched safflower oil (SO) or MUFA-enriched olive oil (OO).

METHODS: We fed mice a high saturated fat diet (HF) (60% kcal from lard) for 12 weeks before substituting half the lard with MO, SO or OO for an additional 4 weeks. At the end of 4 weeks, we assessed glucose tolerance, insulin signalling and reactivity of isolated pressurized gracilis arteries.

RESULTS: After 12 weeks of saturated fat diet, body weights were elevated and glucose tolerance was abnormal compared to mice on control diet (13% kcal lard). Diet substituted with MO restored basal glucose levels, glucose tolerance and indices of insulin signalling (phosphorylated Akt) to normal, whereas restoration was limited for SO and OO substitutions. Although dilation to acetylcholine was reduced in arteries from mice on HF, OO and SO diets compared to normal diet, dilation to acetylcholine was fully restored and constriction to phenylephrine was reduced in MO-fed mice compared to normal.

CONCLUSION: We conclude that short-term enrichment of an ongoing high fat diet with n-3 PUFA rich MO, but not MUFA rich OO or n-6 PUFA rich SO, reverses glucose tolerance, insulin signalling and vascular dysfunction.

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Modification of high saturated fat diet with n‐3 polyunsaturated fat improves glucose intolerance and vascular dysfunction

Abstract

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