Tuesday, May 31, 2016

Paleolithic Diet Trials: Genoni et al


Methods

39 overweight and healthy middle-aged women were randomised to follow a Paleolithic diet of the Australian Guide to Healthy Eating (AGHE) for 4 weeks.  Both diets were ad libitum

“Those in the Paleolithic group were provided with meal ideas obtained from “The Paleo Diet” book and advised to consume lean meats, fish, eggs, nuts, fruits and vegetables, and small amounts of olive or coconut oils. Grains, cereals and dairy products were not permitted. Dairy products were replaced with unsweetened almond milk. Sugarless black coffee and tea were allowed. All vegetables were permitted on the diet, except for corn, white potatoes and legumes. To ensure adequate carbohydrate, additional fruit was recommended. Dried fruit was limited to one tablespoon per day”

“The AGHE group were counselled on how to achieve food variety in line with the five food groups and Australian dietary recommendations; increasing vegetable and fruit intake and whole grain products, reducing fat intake, and consuming low fat dairy products. Advice was also given to reduce intake of discretionary food items such as cakes, biscuits, sugary drinks and candy. Subjects received the AGHE plate poster and fridge magnet”

Results

The Paleo group significantly reduced their energy intake by 24% while the AGHE group reduced their energy intake by 18% and this was near significant.  Protein as a % of total energy intake significantly increased in the Paleo group but absolute intake only increased from 90.2 to 91.2 grams.  Fibre intake wasn’t altered by either diet.  This may initially suggest poor compliance, but it should be remembered that the average energy intake of both groups decreased a fair bit and fibre intake was quite reasonable to begin with (~25g). See table 3 for more results, bold indicates a significant difference


Paleo
AGHE
Δ vs Groups
Pre
Post
Δ
Pre
Post
Δ
Energy intake (kJ)
7798
5915
−1883
8088
6657
−1432
−451
Protein (%)
20.6
26.8
6.19
20.1
21.7
1.52
4.67
Fat (%)
33.6
39.8
6.20
35.8
32.6
−3.20
9.39
Carbohydrate (%)
39.1
27.8
−11.3
37.2
40.6
3.34
−14.63

Contrary to previous studies, differences in micronutrient intake were very mixed, with no diet being clearly superior to another.  The Paleo group improved their intakes of vitamins A, C and E and to a greater extent than the AGHE group, but significantly reduced their intake of thiamine, riboflavin (quite surprising considering main sources of riboflavin are animal foods and veg) and calcium (and iodine and sodium most likely due to the low salt recommendations in 'The Paleo Diet' book).  However, it’s important to remember that the Paleo group were consuming 11% fewer calories (see table 4)  

Unsurprisingly, the Paleo group lost significantly more weight, fat mass, and waist size compared to the AGHE group, though more than you might expect.  Total cholesterol and LDL-C were significantly reduced in both groups, which is not surprising as both groups significantly reduced their intake of saturated fat.  Systolic blood pressure, diastolic blood pressure, fasting glucose and insulin weren’t affected at all by either diet, but were already good to begin with (average blood pressure < 120/80, glucose < 5 mmol/l and insulin < 5 mU/L).  Serum β-carotene and red blood cell folate significantly increased in the Paleo group and to a greater extent than the AGHE group, the β-carotene can be easily explained with the very large increase in β-carotene intake, but folate actually significantly decreased in the Paleo group (a possible explanation is that vitamin B12 can improve folate status?).  See table 1 and 2 for more results, bold indicates a significant difference


Paleo
AGHE
Δ vs Groups
Pre
Post
Δ
Pre
Post
Δ
Body weight (kg)
73.8
70.6
−3.20
73.0
71.8
−1.21
−1.99
Fat mass (kg)
26.2
24.1
−2.14
23.6
23.1
−0.46
−1.68
Fat free mass (kg)
48.5
47.1
−1.38
50.2
49.4
−0.79
−0.59
WC (cm)
85.9
82.5
−3.35
83.0
81.4
−1.55
−1.90

It’s nice to see another Paleo trial and one from Australia too.  Besides micronutrient intakes, this trial didn’t find much more than significantly better weight loss in the Paleo group after 4 weeks.  Obviously, a limitation is that this trial is only 4 weeks long and therefore adherence should still be quite high.  4 weeks is long enough to see changes in things like blood lipids, blood pressure, and glucose/insulin but the latter two didn’t happen because the participants were already quite healthy, just a little overweight

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