tyw
Member
Many people here probably do get at least half their calories from sugars in various forms, likely often at least 15% fructose. (Many also probably get less.) Peat seems to generally favour sugars over starches when good quality is available, and reasonably high sugar/carb intake.
Yes. It doesn't mean that they should though . We are dealing with multiple systems at varying tiers in the hierarchy of metabolism. As a generic rule of thumb, I try to stay on the safe side, and start recommendations at "optimal" values.
The main questions are:
(1) How much fructose is required for metabolic benefits?
(2) Is more fructose going to be more metabolically beneficial?
As for question (1), Peat's "Quart of Orange Juice a day" actually is pretty accurate. That would be about 100g sugar, and let's say 50-60g of fructose depending on source.
Most of the research will show moderate amounts of fructose (10% of total carbohydrate) increasing the rate of glucose oxidation by a wide margin. (Search for "fructose hepatic glucose oxidation" for studies). 10% of total carbohydrate isn't a lot of fructose, ie: you don't need a lot to gain the benefits, and Peat's suggestion of "A Quart of Orange juice" actually provides a sort of nice middle ground for that.
So is more better? If you can handle it, likely yes . But what does "if you can handle it" mean? While I do agree that fructose is not only metabolised in the liver, a substantial portion of it is. There have been previous complaints on this forum about "Peat doesn't consider liver health" to be a factor (I'm Done With Ray Peat Diet. More Hair Loss, Abdominal Problems, Possible Fatty Liver).
This is where I agree that more qualification of personal context is required. Myself for example, can't handle as much fructose when I also eat more protein and fat (not a lot, even 15% of calories as fat gives me some issues). In the end I pinned it down to under-methylation, and supplementation with low-dose Molybdenum and Manganese actually solves the issue. Will this issue resolve itself in the future? Likely yes, but during the recovery process, it probably is a good idea to get "just enough fructose"
People on this forum have also heard the caveats that @haidut has given regarding not going too aggressive with PUFA depletion -- lots of mobilised circulating PUFAs will do some harm, and too much fructose with a PUFA load is also going to be an issue.
NOTE: the 15% fructose value is high in that study specifically given the uncontrolled PUFA intake. This shouldn't necessarily be taken to mean that it is high if PUFA intake is low or close to nothing.
So personally, I'm more conservative in this respect, and will say to stick to some fructose, say 50g a day (100g of sugar, which is basically 10% of calories from fructose in a lowish calorie 2,000kcal diet), which is significant enough to gain benefits, while preventing the downsides.
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