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Depletion Rate
Quote from
tim on February 24, 2019, 3:19 pm
User "franko" over at the Ray Peat forum has done a good job of writing about VA toxicity. He mentions a depletion rate of 0.5%. A depletion rate of 0.5% daily does not equate to 200 days though.
"I don't know what the human equivalent of their retinol stores would be, but Genereux has also said that it is documented that we lose 0.5% of our retinol stores per day so on a VA deficient diet they should have run out of retinol stores in 200 days, on average. So if they survived a year without going blind that's 165 days of being in a VA depleted state. Not supposed to be possible according to their model. They should be blind or eye-diseased if not just dead of VA deficiency by then. If some POWs truly lasted 3.5 years (p. 128 of PFP) on that rice diet without going blind — then it blows the standard VA deficiency model out of the water!"
How much of the original percentage of VA would be left after 200 days if a rate of 0.5% was calculated daily? It would be 0.995^199 = 0.37 so 37%. If VA is an anti nutrient then a linear depletion rate (0.5% of starting total VA per day) would make sense but if it is a vitamin then the formula for depletion is likely to be complex.
User "franko" over at the Ray Peat forum has done a good job of writing about VA toxicity. He mentions a depletion rate of 0.5%. A depletion rate of 0.5% daily does not equate to 200 days though.
"I don't know what the human equivalent of their retinol stores would be, but Genereux has also said that it is documented that we lose 0.5% of our retinol stores per day so on a VA deficient diet they should have run out of retinol stores in 200 days, on average. So if they survived a year without going blind that's 165 days of being in a VA depleted state. Not supposed to be possible according to their model. They should be blind or eye-diseased if not just dead of VA deficiency by then. If some POWs truly lasted 3.5 years (p. 128 of PFP) on that rice diet without going blind — then it blows the standard VA deficiency model out of the water!"
How much of the original percentage of VA would be left after 200 days if a rate of 0.5% was calculated daily? It would be 0.995^199 = 0.37 so 37%. If VA is an anti nutrient then a linear depletion rate (0.5% of starting total VA per day) would make sense but if it is a vitamin then the formula for depletion is likely to be complex.
Doublecapricorn has reacted to this post.
Quote from
Bella on February 24, 2019, 3:51 pm
I am shamelessly copying and pasting this from a post at RPF by user Amazoniac.
A = Percent of body vitamin A stores lost per day when ingesting a vitamin A-free diet
"The portion of body vitamin A stores lost per day has been estimated to be 0.5 percent based on the rate of excretion of radio-activity from radiolabeled vitamin A and by the calculation of the half-life of vitamin A."
In the experiment that served as base, the half-life of stored poison varied a lot. According to their extremes, in one person it took 75 days to deplete the body content in half; in other, 241 days. Of the 8 people being monitored (including those 2), the mean half-life of the reserves was 154 days. If it takes 154 days to deplete 50% of the stores, they assume that
0.32% (50% ÷ 154) is lost a day.
- Vitamin A Metabolism and Requirements in the Human Studied with the Use of Labeled Retinol (posted in this thread before)
There's a different approach to it, but the researcher didn't provide enough details, so it has been tough to get how he arrived at it. I'm not sure if I'll try to work it out, however it doesn't change the rate of depletion because in both they round them to 0.5% like savages.
The percentages above are gross simplifications because it's considering that the process is linear at all times. Yeet!The rate of utilization is high at the beginning and lowers the closer you get to depletion. You might deplete half of your stores relatively fast, but the other half is more difficult; and if you divide the second half in two, the last period lasts longer than the previous, and so on if you continue half-lifeing them.
Either way, in rounding to this higher percentage (0.5%) they is assuming it to be depleted faster, which in turn reflects in recommending higher intakes to replenish what's used/lost daily. But at the same time, unless you remain without ingesting poison for the entire specified half-life, the actual depletion rate in the initial moment might be that great, if not greater than that. Fragmentation of the periods also minimize problems when you consider each of them linear. So these aspects might cancer each other out.
So perhaps it makes sense to use it for practical purposes given that they have regular consumption in the minds. The variation between gurus is still insane, but it will be taken into consideration later on (although by pushing recommendations higher as solution).
I am shamelessly copying and pasting this from a post at RPF by user Amazoniac.
A = Percent of body vitamin A stores lost per day when ingesting a vitamin A-free diet
"The portion of body vitamin A stores lost per day has been estimated to be 0.5 percent based on the rate of excretion of radio-activity from radiolabeled vitamin A and by the calculation of the half-life of vitamin A."
In the experiment that served as base, the half-life of stored poison varied a lot. According to their extremes, in one person it took 75 days to deplete the body content in half; in other, 241 days. Of the 8 people being monitored (including those 2), the mean half-life of the reserves was 154 days. If it takes 154 days to deplete 50% of the stores, they assume that
0.32% (50% ÷ 154) is lost a day.
- Vitamin A Metabolism and Requirements in the Human Studied with the Use of Labeled Retinol (posted in this thread before)
There's a different approach to it, but the researcher didn't provide enough details, so it has been tough to get how he arrived at it. I'm not sure if I'll try to work it out, however it doesn't change the rate of depletion because in both they round them to 0.5% like savages.
The percentages above are gross simplifications because it's considering that the process is linear at all times. Yeet!The rate of utilization is high at the beginning and lowers the closer you get to depletion. You might deplete half of your stores relatively fast, but the other half is more difficult; and if you divide the second half in two, the last period lasts longer than the previous, and so on if you continue half-lifeing them.
Either way, in rounding to this higher percentage (0.5%) they is assuming it to be depleted faster, which in turn reflects in recommending higher intakes to replenish what's used/lost daily. But at the same time, unless you remain without ingesting poison for the entire specified half-life, the actual depletion rate in the initial moment might be that great, if not greater than that. Fragmentation of the periods also minimize problems when you consider each of them linear. So these aspects might cancer each other out.
So perhaps it makes sense to use it for practical purposes given that they have regular consumption in the minds. The variation between gurus is still insane, but it will be taken into consideration later on (although by pushing recommendations higher as solution).
tim has reacted to this post.
Quote from
tim on February 24, 2019, 10:39 pm
Wow thanks Bella, good info.
Wow thanks Bella, good info.
Quote from
Orion on February 25, 2019, 6:51 am
So it looks safe to say that if you are on a complete VA deplete diet, ~300 days average should get you down to 0 range. But we know how hard it is to avoid in most foods. 1 year is a good round number. Look forward to the 1 year update posts, later this year 🙂
So it looks safe to say that if you are on a complete VA deplete diet, ~300 days average should get you down to 0 range. But we know how hard it is to avoid in most foods. 1 year is a good round number. Look forward to the 1 year update posts, later this year 🙂
Quote from
ZJ on February 25, 2019, 1:10 pm
It's going to very a lot from person to person based on how much V.A. they're starting with, how little V.A. they consume, protein intake, zinc status, kidney and liver function, etc. But I'm thinking 1-3+ years to get to virtually zero.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2854912/
In early studies, a depletion-repletion method was used, which involved measurement of the repletion doses of β-carotene and vitamin A that were needed to reverse vitamin A deficiency in depleted adults. This approach is no longer acceptable. A depletion study (23) was conducted in 16 healthy subjects between the ages of 19 and 34 y (7 additional subjects served as positive controls). After 12 mo of depletion, only 3 of the subjects were vitamin A deficient; a blood concentration <0.35 μmol/L (10 μg/dL) and deterioration in dark adaptation were used to define “unmistakably deficient” subjects. Of the 3 subjects with vitamin A deficiency, 2 were given β-carotene and one was given preformed vitamin A. Daily doses of 1500 μg β-carotene or 390 μg retinol for 3 wk to 6 mo were sufficient to reverse vitamin A deficiency in these subjects. Therefore, from this human study, the β-carotene/vitamin A equivalence was determined to be 3.8:1 by weight. In 1974, another vitamin A depletion-repletion study in human subjects was reported (24). Eight healthy male subjects aged 31–43 y were depleted in vitamin A within 359–771 d. Five subjects were then given vitamin A and 3 subjects were given β-carotene. Daily doses of 600 μg retinol or 1200 μg β-carotene were required to cure vitamin A deficiency. In this study, the β-carotene-to-vitamin-A equivalence was, therefore 2:1 by weight. In these studies, all subjects had been made deficient in vitamin A, so it cannot be determined whether a 3.8- or 2-μg equivalence of β-carotene to 1 μg retinol is applicable in vitamin-A–sufficient individuals.
It's going to very a lot from person to person based on how much V.A. they're starting with, how little V.A. they consume, protein intake, zinc status, kidney and liver function, etc. But I'm thinking 1-3+ years to get to virtually zero.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2854912/
In early studies, a depletion-repletion method was used, which involved measurement of the repletion doses of β-carotene and vitamin A that were needed to reverse vitamin A deficiency in depleted adults. This approach is no longer acceptable. A depletion study (23) was conducted in 16 healthy subjects between the ages of 19 and 34 y (7 additional subjects served as positive controls). After 12 mo of depletion, only 3 of the subjects were vitamin A deficient; a blood concentration <0.35 μmol/L (10 μg/dL) and deterioration in dark adaptation were used to define “unmistakably deficient” subjects. Of the 3 subjects with vitamin A deficiency, 2 were given β-carotene and one was given preformed vitamin A. Daily doses of 1500 μg β-carotene or 390 μg retinol for 3 wk to 6 mo were sufficient to reverse vitamin A deficiency in these subjects. Therefore, from this human study, the β-carotene/vitamin A equivalence was determined to be 3.8:1 by weight. In 1974, another vitamin A depletion-repletion study in human subjects was reported (24). Eight healthy male subjects aged 31–43 y were depleted in vitamin A within 359–771 d. Five subjects were then given vitamin A and 3 subjects were given β-carotene. Daily doses of 600 μg retinol or 1200 μg β-carotene were required to cure vitamin A deficiency. In this study, the β-carotene-to-vitamin-A equivalence was, therefore 2:1 by weight. In these studies, all subjects had been made deficient in vitamin A, so it cannot be determined whether a 3.8- or 2-μg equivalence of β-carotene to 1 μg retinol is applicable in vitamin-A–sufficient individuals.
Quote from Guest on February 25, 2019, 2:05 pm
Here's a source for the original 0.5% number.
Retinol distribution and catabolism was determined in eight male adult subjects who received intravenous or oral doses of [14C]‐labelled retinyl acetate during vitamin A depletion (up to 771 days) and repletion (up to 372 days) (Sauberlich et al., 1974). It took about 26 days for the labelled dose to equilibrate with the total body vitamin pool that was estimated to range from 315–879 mg (1100– 3070 μmol). A fractional catabolic rate of total body retinol stores of approximately 0.5 % per day (range 0.3–0.9 %) was determined in these subjects consuming a vitamin A free diet, deduced from a mean half-life of retinol in the liver of 154 days (range 75–241 days, CV 35 %) during the depletion phase (Sauberlich et al., 1974; Olson, 1987). The absolute retinol utilisation rate ranged between 1113 and 2070 μg (3.9 and 7.2 μmol) per day among subjects at baseline and fell to low levels as depletion progressed (50–180 μg (0.2–0.6 μmol) per day).
DRAFT SCIENTIFIC OPINION
Scientific Opinion on Dietary Reference Values for vitamin
EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA)
European Food Safety Authority (EFSA), Parma, Italy
Here's a source for the original 0.5% number.
Retinol distribution and catabolism was determined in eight male adult subjects who received intravenous or oral doses of [14C]‐labelled retinyl acetate during vitamin A depletion (up to 771 days) and repletion (up to 372 days) (Sauberlich et al., 1974). It took about 26 days for the labelled dose to equilibrate with the total body vitamin pool that was estimated to range from 315–879 mg (1100– 3070 μmol). A fractional catabolic rate of total body retinol stores of approximately 0.5 % per day (range 0.3–0.9 %) was determined in these subjects consuming a vitamin A free diet, deduced from a mean half-life of retinol in the liver of 154 days (range 75–241 days, CV 35 %) during the depletion phase (Sauberlich et al., 1974; Olson, 1987). The absolute retinol utilisation rate ranged between 1113 and 2070 μg (3.9 and 7.2 μmol) per day among subjects at baseline and fell to low levels as depletion progressed (50–180 μg (0.2–0.6 μmol) per day).
DRAFT SCIENTIFIC OPINION
Scientific Opinion on Dietary Reference Values for vitamin
EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA)
European Food Safety Authority (EFSA), Parma, Italy
Quote from
Bella on February 25, 2019, 5:26 pm
Thanks Guest, Tim, ZJ and Orion. So it looks like 1-2 years? I'm guessing for those of us who actually megadosed A and used pharma A drugs all while eating lots of A and carotenoids we might be looking at closer to two years? I understand it will vary depending on sex, age etc as well.
I must say my detox phases are getting much milder and I'm not as sensitive to things like small amounts of butter which is promising although I still mostly restrict it.
Thanks Guest, Tim, ZJ and Orion. So it looks like 1-2 years? I'm guessing for those of us who actually megadosed A and used pharma A drugs all while eating lots of A and carotenoids we might be looking at closer to two years? I understand it will vary depending on sex, age etc as well.
I must say my detox phases are getting much milder and I'm not as sensitive to things like small amounts of butter which is promising although I still mostly restrict it.
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