Saturday, January 30, 2016

Paleolithic Diet Trials: Mellberg, et al (Part 2)


This paper was published recently regarding the Mellberg Paleo diet trial, which I have previously blogged about here

To summarise: the Mellberg trial involved 70 postmenopausal, obese women who followed a Paleo diet* or the Nordic Nutrition Recommendations (NNR)** (low fat conventional dietary advice) for 2 years (both diets were ad libitum).  The Paleo group lost more weight at 6 months, but both groups were similar at 24 months.  There were no other significant differences between the groups regarding blood lipids, blood pressure and some biomarkers, except for a greater reduction in plasma triglycerides in the Paleo group.  Compliance was pretty poor in both groups

* “The Paleolithic diet (PD) was based on fish, seafood, lean meat, eggs, nuts, fruits and vegetables. Cereals, dairy products, legumes, added salt, and sugar were excluded. The PD aimed to provide 40 E% as fat with a high intake of mono- and polyunsaturated fatty acids. 30 E% were planned to come from carbohydrates and 30 E% from protein.”

** “The conventional low-fat diet (LFD) was based on the Nordic Nutrition Recommendations (16). The women were advised to increase their intake of fruit, vegetables, whole grain, and fish. Meat and dairy products were to be low-fat. The LFD aimed to provide 25-30 E% as fat, 55-60 E% as carbohydrates, and 15 E% as protein.”


Energy (kcal)
Protein (%)
Fat (%)
Carb (%)
PD
Target
-
30.0
40.0
30.0
Baseline
2000
17.1
33.4
46.2
6 Months
1625
23.4
43.4
29.3
24 Months
1599
21.9
40.4
33.5
NNR
Target
-
15.0
20.0-25.0
55.0-60.0
Baseline
2019
17.2
34.6
45.3
6 Months
1660
18.8
32.3
44.2
24 Months
1758
17.4
34.9
43.3

The current study investigated how a Paleo diet and the NNR would affect liver fat and insulin sensitivity.  Citing previous Paleo trials and evidence from that suggests MUFAs lower liver fat, the researchers hypothesised that the Paleo group would have a greater reduction in liver fat and greater improvements in insulin sensitivity

Due to differences in baseline liver fat, the Paleo group had a greater percentage reduction of liver fat while the NNR group had a greater absolute reduction in liver fat at 24 months.  Only the Paleo group had some (often not lasting) improvements in fasting insulin and liver insulin resistance (IR) and none of the groups had significant improvements in measures of peripheral (muscle mostly) insulin resistance.  Again, compliance was pretty bad (see table above), so pretty uneventful results are to be expected

Visceral adipose tissue, liver fat and insulin sensitivity were closely related at baseline, but these associations weren’t consistent after the diet interventions.  The reduction in liver fat was associated with weight loss in the NNR group, but not in the Paleo group, and there were no significant correlations between changes in liver fat and changes in insulin sensitivity (I'll discuss that relationship some other time)


Paleo
NNR
0
6
24
0
6
24
Body composition
BMI
32.6
29.2
29.5
32.0
30.4
30.2
Lean mass (kg)
41.6
40.0
40.0
41.1
40.9
40.5
Fat mass (kg)
39.6
32.4
34.4
38.6
34.9
34.7
Liver fat (%)
4.6
1.2
1.6
8.6
5.2
4.3
Liver IR
Liver IR index
4.78
4.60
4.70
4.75
4.70
4.81
HOMA-IR
1.97
1.31
1.79
2.15
2.10
2.56
Peripheral IR
OGIS
400
412
422
379
396
373
Matsuda
93
111
105
78
86
75
Glucose metabolism
Fasting glucose
5.0
4.9
4.9
5.4
5.4
5.4
2h Glucose
7.2
6.6
7.0
6.9
7.2
7.4
Fasting insulin
8.6
6.0
8.0
9.0
8.5
10.3
Bold = significantly different between groups
Underline = significantly different within group

* Of the original 70 (35 in each group) this paper only has results from 25 in the Paleo group and 16 in the NNR group due to withdrawals and issues in getting these results

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