Dried Mango For Vitamin A?

[Travis]

"Hydrogen atoms in this position are exceptionally active and can reduce the Carbonyl initiators as well as the free radical carriers of the oxidation chains." ―William Koch MD, PhD​

William Koch appears to be correct about the α-carbon; his Ph.D. was in chemistry. Below is what Timothy Soderberg has to say about the hydrogen on the α-carbon:

"The key concept to recall from what we have learned about acidity and basicity in organic chemistry, and to keep in mind throughout this discussion, is that α-protons (in other words, protons on α-carbons) are weakly acidic. Loss of an α-proton forms an enolate - a species in which a negative formal charge is delocalized between a carbon and an oxygen." ―Soderberg

"Let's review what we learned in section 7.6A about the acidity of a proton on an α-carbon and the structure of the relevant conjugate base, the enolate ion. Remember that this acidity can be explained by the fact that the negative charge on the enolate conjugate base is delocalized by resonance to both the α-carbon and the carbonyl oxygen." ―Soderberg

➫ Soderberg, Timothy. "Organic chemistry with a biological emphasis." (2016).​

Its fashionable to call hydrogen atoms (·H) without their electron simply a proton (H⁺), because this is what they usually are. But this is actually incorrect, as hydrogen has three natural isotopes: hydrogen (¹H), deuterium (²H), and tritium (³H). This means: When referring to the naked nuclei of hydrogen as "protons," you are wrong about 0.0156% of the time—when its a proton and a neutron.. . ..or sometimes even two.

Koch never ceases to amaze.. . ..and doesn't fall for that trap!

 

[Jennifer]

I notice a lot of people talking about Vitamin A and when I punch it into Cronometer, it seems like the Dried Mango from Trader Joe's supplies more than what could be necessary for a daily total. This particular variety is not sulfured and not sweetened. Does anybody see a hitch in this?

I'm addicted to TJ's dried mango. I have a few varieties from them that aren't sulfured or sweetened. There's the "Just Mango" slices from Mexico, Peru and India, the Chokanan variety from Thailand and the Carabao variety from the Philippines. I find the moist, sticky and tender qualities of the Caraboa variety to be unique for a dried fruit, but I like the "Just Mangos" the best. I know I've overdone the beta-carotene when I start to resemble an Oompa Loompa, but I eat a fruitarian diet so we're talking a ton of beta-carotene rich fruits for that to happen.

 

[tara]

I'm still waiting for that orange skin tone, but this appears to be induced only by carrots.. . ..and I don't really eat carrots. I've eaten multiple papayas per day for weeks without getting the orange skin tone; so whole carotenes don't appear to be absorbed very well.

I've wondered about this. I've had a particular aversion to excess cooked carrot, pumpkin and orange coloured sweet potatoes. I don't have to eat very many in a week to hit that limit, and I've earned to respect it. I used to have more noticably orange callouses, now my skin is pinker and only the thickest callouses show a little of the orange tinge. I guessed that I was having trouble with the beta carotenes. I can eat a bit more raw carrot before it gets to me, but if I want to eat raw carrot every day for a week I have to grate and rinse. I've never had the opportunity to eat enough mango or papaya to know whether/when I'd get get fed up with them. Apricots I can eat quite a few of during the short season, and now and then have a few dried ones, but maybe there is a limit I haven't been able to afford to reach. I've never noticed the same reaction to leafy greens, and I eat cooked greens most days. They have some of the beta-carotenes too, don't they?

 

[Travis]

I've wondered about this. I've had a particular aversion to excess cooked carrot, pumpkin and orange coloured sweet potatoes. I don't have to eat very many in a week to hit that limit, and I've earned to respect it. I used to have more noticably orange callouses, now my skin is pinker and only the thickest callouses show a little of the orange tinge. I guessed that I was having trouble with the beta carotenes. I can eat a bit more raw carrot before it gets to me, but if I want to eat raw carrot every day for a week I have to grate and rinse. I've never had the opportunity to eat enough mango or papaya to know whether/when I'd get get fed up with them. Apricots I can eat quite a few of during the short season, and now and then have a few dried ones, but maybe there is a limit I haven't been able to afford to reach. I've never noticed the same reaction to leafy greens, and I eat cooked greens most days. They have some of the beta-carotenes too, don't they?

I never had noticed that it could be from cooking; that's a good observation. Perhaps the cooking breaks down the fibre so the carotenes are better absorbed whole in the small intestine.

I often eat one pound of raw kale per day, but not a whole lot of carotenes besides. But I have been on rampages! carotene binges, when mangoes were both good and 50¢ apiece. A few years ago, someone at the grocery store I'd go to started to price papayas incorrectly; they went from $1/lb to $1 apiece overnight, apparently by mistake, making them perhaps the cheapest papayas ever recorded in The Midwest (after adjusting for inflation).

Leaves certainly do have quite a bit of carotenes, but you wouldn't know just by looking at them. It seems as thought the light spectrum of the leaf is more dominated by the chlorophyll.

 

[fradon]

I notice a lot of people talking about Vitamin A and when I punch it into Cronometer, it seems like the Dried Mango from Trader Joe's supplies more than what could be necessary for a daily total. This particular variety is not sulfured and not sweetened. Does anybody see a hitch in this?

only if you have oxalate problems as dried fruit is high in oxalates. also you might go with some like liver as it has retinol the final form of vitamin A.

 

[Arnold Grape]

So it's a choice between the liver or dried mango?

 

[Sucrates]

With high consumption of β-carotene or retinol, the carotene cleavage enzyme appears to be downregulated. Though perhaps not an official enzyme name, the term "carotene cleavage enzyme" is often used, regardless—an intuitive less-formal nickname. Let me see if I can find-out what the other name is, since I forgot:

• Wyss, Adrian. "Carotene oxygenases: a new family of double bond cleavage enzymes." The Journal of nutrition 134.1 (2004): 246S-250S.

Of course, it's an oxygenase. You might expect it to be classified as such because it turns a double bond into two aldehydes (retinals), ostensibly by adding O₂ to the double bond—almost like a controlled lipid peroxidation event. As another O₂-shepherding enzyme (protein), you might also expect it to contain heme, like cyclooxygenase and hemoglobin.

• Zaripheh, Susan, et al. "Dietary lycopene downregulates carotenoid 15, 15′-monooxygenase and PPAR-γ in selected rat tissues." The Journal of nutrition 136.4 (2006): 932-938.
• Bachmann, Heinrich, et al. "Feedback regulation of β, β-carotene 15, 15′-monooxygenase by retinoic acid in rats and chickens." The Journal of nutrition 132.12 (2002): 3616-3622.
  • "We found dose-dependent decreases in intestinal β,β-carotene monooxygenase activity after oral administration to rats of retinyl acetate (up to −79%), β-carotene (up to −79%), apo-8′-carotenal (up to −56%), all-transretinoic acid (up to −88%), and 9-cisretinoic acid (up to −67%). Liver β,β-carotene 15,15′-monooxygenase (βCMOOX) activity was not affected. Apo-12′carotenal and the retinoic acid receptor (RAR) α antagonist Ro 41-5253 significantly increased the intestinal enzyme activity by 55 and 94%, respectively. [...] Our data suggest that retinoids and carotenoids might regulate βCMOOX expression by a transcriptional feedback mechanism via interaction with members of the RAR family." ―Bachmann

Which appears to be why higher chronic doses of β-carotene don't appear to cause hypervitaminosis A. If this regulatory feedback system is working well, this would make high-dose β-carotene about equally as effective as low-dose β-carotene for producing retinal. The implications are obious: High dose β-carotene is a complete waste of money! (although some β-carotene could be absorbed whole, where it could potentially act as a general antioxidant.. . . ..or perhaps even a disruptor of eicasanoid signalling?)

I'm still waiting for that orange skin tone, but this appears to be induced only by carrots.. . ..and I don't really eat carrots. I've eaten multiple papayas per day for weeks without getting the orange skin tone; so whole carotenes don't appear to be absorbed very well.

The only bad reaction that I've had to mangoes came from the sap, that sticky exudate which can be found near the stem.

Thanks for the explanation, @Travis .