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Strong and persistent effect on liver fat with a Paleolithic diet during a two-year intervention
Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för medicin.
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2016 (Engelska)Ingår i: International Journal of Obesity, ISSN 0307-0565, E-ISSN 1476-5497, Vol. 40, nr 5, s. 747-753Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

BACKGROUND/OBJECTIVES: Our objective was to investigate changes in liver fat and insulin sensitivity during a 2-year diet intervention. An ad libitum Paleolithic diet (PD) was compared with a conventional low-fat diet (LFD).

SUBJECTS/METHODS: Seventy healthy, obese, postmenopausal women were randomized to either a PD or a conventional LFD. Diet intakes were ad libitum. Liver fat was measured with proton magnetic resonance spectroscopy. Insulin sensitivity was evaluated with oral glucose tolerance tests and calculated as homeostasis model assessment-insulin resistance (HOMA-IR)/liver insulin resistance (Liver IR) index for hepatic insulin sensitivity and oral glucose insulin sensitivity (OGIS)/Matsuda for peripheral insulin sensitivity. All measurements were performed at 0, 6 and 24 months. Forty-one women completed the examinations for liver fat and were included.

RESULTS: Liver fat decreased after 6 months by 64% (95% confidence interval: 54-74%) in the PD group and by 43% (27-59%) in the LFD group (P<0.01 for difference between groups). After 24 months, liver fat decreased 50% (25-75%) in the PD group and 49% (27-71%) in the LFD group. Weight reduction between baseline and 6 months was correlated to liver fat improvement in the LFD group (rs=0.66, P<0.01) but not in the PD group (rs=0.07, P=0.75). Hepatic insulin sensitivity improved during the first 6 months in the PD group (P<0.001 for Liver IR index and HOMA-IR), but deteriorated between 6 and 24 months without association with liver fat changes.

CONCLUSIONS: A PD with ad libitum intake had a significant and persistent effect on liver fat and differed significantly from a conventional LFD at 6 months. This difference may be due to food quality, for example, a higher content of mono- and polyunsaturated fatty acids in the PD. Changes in liver fat did not associate with alterations in insulin sensitivity.International Journal of Obesity advance online publication, 16 February 2016; doi:10.1038/ijo.2016.4.

Ort, förlag, år, upplaga, sidor
2016. Vol. 40, nr 5, s. 747-753
Nationell ämneskategori
Näringslära
Identifikatorer
URN: urn:nbn:se:umu:diva-117538DOI: 10.1038/ijo.2016.4ISI: 000377616500003PubMedID: 26786351OAI: oai:DiVA.org:umu-117538DiVA, id: diva2:907961
Forskningsfinansiär
Vetenskapsrådet, K2011-12237-15-6Tillgänglig från: 2016-03-01 Skapad: 2016-03-01 Senast uppdaterad: 2019-05-22Bibliografiskt granskad
Ingår i avhandling
1. Effects of a Paleolithic diet and exercise on liver fat, muscle fat and insulin sensitivity
Öppna denna publikation i ny flik eller fönster >>Effects of a Paleolithic diet and exercise on liver fat, muscle fat and insulin sensitivity
2016 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Finding ways to reduce risk for obesity-related disorders, including type 2 diabetes and cardiovascular disease, is important. Such approaches can include lifestyle interventions by diet and exercise. Our ancestors in the Paleolithic Era ate a diet based on vegetables, fruit, berries, lean meat, fish, seafood, nuts and eggs. Cereals, dairy products and legumes were not a significant part of the diet before the agricultural revolution, and neither were added sugar or salt. Furthermore, our ancestors were much more physically active compared to the average Western population.

Contemporary hunter-gatherers like the Kitava Islanders and the Greenlandic Inuit eat a diet similar to that of the Paleolithic Era and have a strikingly low frequency of cardiovascular events. Detailed studies of the metabolic effects of the Paleolithic diet, with and without exercise, are therefore warranted.

Impaired insulin sensitivity is a key factor in the development of type 2 diabetes and cardiovascular disease. In this thesis, insulin sensitivity was measured with the gold-standard examination – the hyperinsulinemic– euglycemic clamp – and also with fasting blood samples and the oral glucose tolerance test. We found the fasting index Revised QUICKI to be the best choice if the time-consuming gold-standard examination is not feasible. However, to distinguish insulin sensitivity of different tissues like skeletal muscle, liver and adipose tissue, the hyperinsulinemic–euglycemic clamp is preferred.

In our studies, the Paleolithic diet improved cardiovascular risk factors like overweight, insulin sensitivity, liver fat, triglycerides and blood pressure in obese, postmenopausal women. All study participants decreased liver fat when eating a Paleolithic diet. Six months of Paleolithic diet improved weight, liver fat and triglycerides significantly more than a conventional low-fat diet in obese, postmenopausal women. It was difficult for the women to remain adherent to the Paleolithic diet for 2 years, however, and most cardiovascular risk factors showed some degree of deterioration between 6 and 24 months. In individuals with type 2 diabetes, a Paleolithic diet for 12 weeks improved weight, insulin sensitivity, HbA1c, triglycerides and blood pressure. Exercise training did not improve these cardiovascular risk factors beyond the changes observed with the Paleolithic diet alone. The 12-week Paleolithic diet intervention also reduced muscle fat and liver fat, but exercise training reversed this effect.

A Paleolithic diet has strong effects on fat content in liver and muscle and on insulin sensitivity. Our present results indicate reduced metabolic flexibility in the fat content in liver and muscle tissue among patient with type 2 diabetes, which may improve through diet and exercise intervention. 

Ort, förlag, år, upplaga, sidor
Umeå: Umeå University, 2016. s. 73
Serie
Umeå University medical dissertations, ISSN 0346-6612 ; 1839
Nyckelord
type 2 diabetes, liver fat, Paleolithic diet, exercise training, insulin sensitivity, overweight, intramyocellular lipid content
Nationell ämneskategori
Endokrinologi och diabetes
Identifikatorer
urn:nbn:se:umu:diva-126189 (URN)978-91-7601-548-3 (ISBN)
Disputation
2016-10-28, Hörsal 933, trapphus B, Norrlands universitetssjukhus, Umeå, 09:00 (Svenska)
Opponent
Handledare
Tillgänglig från: 2016-10-07 Skapad: 2016-10-03 Senast uppdaterad: 2018-08-27Bibliografiskt granskad

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