Part 1
I've spent an inordinate amount of time on this, and related, studies over the last few weeks
Ability of high fat diet to induce liver pathology correlates with the level of linoleic acid and Vitamin E in the diet
There are serious problems with panel A of Figure 1:
Ordinary mice on chow typically eat in the region of 14kcal/d, ie 98kcal/wk. High growth rate mice can eat 18kcal/d, ie 140kcal/wk. So the chow column is plausible as energy intake per mouse per week. Some mice are reported to eat as little as 9kcal/d on chow. There's a range.
What is not plausible is that mice on high fat diets ate 20% less total calories than the chow fed mice while gaining 20-40% more bodyweight, all as adipose tissue. This doesn't make sense.
In general rodents on obesogenic high fat diets consume very slightly *more* calories per day over the weeks than chow fed mice. The weight of food needed to get those calories will obviously be reduced because there are extra calories per gram. So calorie intake usually ends up slightly increased but on a lower food ingestion weight.
Just for illustration here are the energy intakes from mice fed a 45% lard based diet discussed in the next post. They are typical. Outlined in blue are the numbers we need:
Call me a Cicotard if you like, but the panel A graph from Figure 1 suggests either massive, and I mean massive, uncoupling in the chow fed mice. Which I doubt. Or a catastrophically reduced daily energy expenditure in the high fat diet fed mice, *irrespective* of linoleic acid intake. Which I also doubt. Greatly.
It almost looks like there has been a mix up of weight of food consumed and the total calories consumed per week.
But that doesn't reverse engineer easily. If we say the 110kcal/week specified for the chow mice is actually 110 grams/week then that's 16g of chow each day. No mouse can eat this much chow per day. If we assume that it's for the whole of the group of four in the cage we get a food intake of 4g/d/mouse. Which is plausible.
But who knows? That's a lot of guesswork.
It's a bugger because we need to know how much food each mouse ate in order to determine how much actual vitamin E each consumed.
We are given the vitamin E per kg diet, and the number looks plausible. Looking at Table S2 we have the data for the chow (PicoLab Rodent Diet 20/LabDiet 5053) and can calculate the value for this well recognised and standardised diet.
Diet 5053 contains 99iu/kg of vitamin E acetate on the product sheet. This gives, assuming synthetic vitamin E, 89.1mg/kg vit E. From this calculator we have:
Also assuming the synthetic vit E is a 50:50 mix of the d and l isomers, we have, of active form, half that, giving 45.55mg/kg, as here in Table S2
On this basis I think it is very likely that the absolute amount of vitamin E in all of the diets in this paper are correct in Table S2.
If we deconstruct the (excellent) Table S2 to remove the arithmetic lines we can summarise the amounts of vitamin E in different diets like this
If we take Lab Diet 5053 to represent some semblance of a normal to generous level of vitamin E for normal growth and reproduction of rodents eating one of the most widely available chows in the world we have the low LA diets with less absolute vitamin E than 5053 and the high LA diet containing rather more vitamin E than the 5053 chow diet.
Working through the rest of the (largely appalling) vitamin E-HFD literature most groups would consider vitamin E at 50mg/kg of diet to be low dose and 200mg/kg to be high dose. Those would be dose rates of d-α-tocopherol. So we are looking at low versus moderate in this study.
Now we are in a position to look at the weight loss effects of various levels of vitamin E in various diets.
Peter
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