this post was submitted on 17 Jun 2026
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[YT short] Dr Paul Mason on vitamin D seed, oil, sunburn (youtu.be)
submitted 11 hours ago by psud@aussie.zone to c/carnivore@discuss.online
18 comments fedilink hide all child comments
 

Do seed oils block cholesterol to vitamin D? Vitamin D as sunscreen Sunburn resistance of people who don't eat seed oils

It's only a minute, so no summary

top 18 comments
sorted by: hot top controversial new old
[–] mech@feddit.org 4 points 9 hours ago* (last edited 9 hours ago) (3 children)

The premise for his argument is "humans produce vitamin D as a sunscreen".
Which...what?? No. Humans produce melanin as natural sunscreen, not vitamin D.

The next premise is that phytosterols interfere with "a lot of processes", and "maybe Vitamin D production is one of them".
Well yeah, maybe...or maybe not, who the fuck knows without any evidence?

And his evidence that eliminating seed oils from diet leads to resistance to sunburn is (which he admits) anecdotal.
"I've heard dozens of people tell me this." lol.

For the love of god (and especially your children), eat what you want, but don't tell people it has magical powers and lets them avoid skin cancer, unless you have really solid medical proof from large studies on your side.

[–] xep@discuss.online 2 points 3 hours ago* (last edited 3 hours ago)

Humans produce melanin as natural sunscreen, not vitamin D

Please see

https://www.explorationpub.com/Journals/em/Article/1001225

While UV-induced photoaging causes a detrimental impact on the skin, the UVB induced cutaneous synthesis of vitamin D protects the skin from various stresses.

The paper covers some of the mechanisms, it's a good read and will improve your understanding of our body. Melanin isn't the only protective factor.

https://pubmed.ncbi.nlm.nih.gov/23069805

We present data to show that 1,25(OH)(2)D(3) protects skin cells from at least three forms of UV-induced DNA damage, and provide further evidence to support the proposal that a reduction in RNS by 1,25(OH)(2)D(3) is a likely mechanism for its photoprotective effect against oxidative and nitrative DNA damage, as well as cyclobutane pyrimidine dimers.

Not open access, so you'll have to find the full paper yourself.

[–] psud@aussie.zone 4 points 8 hours ago (1 children)

The premise for his argument is "humans produce vitamin D as a Sunscreen"

Which...what?? No. Humans produce melanin as natural sunscreen, not vitamin D.

Yes melanin protects us from sunlight, but what's your source for vitamin D not being protective against sun damage?

[–] mech@feddit.org 1 points 8 hours ago (1 children)

what’s your source for vitamin D not being protective against sun damage?

That's not how evidence works.
If you claim Vitamin D has an effect that was unknown before, you need to provide evidence for that.
Without evidence, the default is "no known effect".

[–] xep@discuss.online 2 points 3 hours ago* (last edited 3 hours ago)

psud is not making a claim, the effects of vitamin D protecting against sun damage is something we already know about. It is not hitherto unknown. Please see my other post on the topic.

Since your claim goes against the scientific literature, he is correct in asking for your sources, so we can verify them.

[–] jet@hackertalks.com 4 points 9 hours ago (1 children)

The premise for his argument is “humans produce vitamin D as a sunscreen”.

The argument is that plant sterols interfere with cholesterol function, impacting systems all over the body including vitamin d production.

Well yeah, maybe…or maybe not, who the fuck knows without any evidence?

https://doi.org/10.1159/000337881 -

Effect of Plant Sterols on Vitamin D AbsorptionCholecalciferol (vitamin D 3 ) is either obtained from the diet or produced photochemically in the skin from 7-dehydrocholesterol, which is produced in relatively large quantities from cholesterol in the gut1 and is accumulated in the skin [1]. Since plant sterols and stanols alter micelle formation and decrease absorption of cholesterol, it is possible that absorption of fat-soluble nutrients including fat soluble vitamins is also affected.

The objective was to examine if plant sterols interfere with the absorption and possibly the synthesis of vitamin D3 . A randomized study was conducted in 40 apparently healthy adult volunteers aged 18–60 years who received orally either 25000 IU vitamin D 3 (group A, n = 20) or 25000 IU vitamin D3 together with 2 g plant sterols (Group B, n = 20). Levels of Vitamin D 3 , 25-hydroxyvitamin D 3 , calcium, phosphorus, magnesium, cholesterol and parathyroid hormone were measured in blood taken immediately before consumption of Vitamin D 3 and at 12 h, 24 h and 168 h (7 days) after administration of Vitamin D 3 . Serum vitamin D 3 concentration increased significantly in both groups at 12 h and 24 h and 25-hydroxyvitamin D3 at 168 h after the consumption of vitamin D. Group B had lower vitamin D 3 levels 12 hours and 24 hours after administration and lower 25-hydroxyvitamin D 3 levels at 168 h after administration.

Hence, inhibiting the absorption of cholesterol may also affect the absorption of vitamin D 3 . Long term (> 4 weeks) administration of sterols is needed to investigate the impact on Vitamin D absorption and consequently its metabolism.

It's well known seed oils will lower LDL cholesterol, this is a direct demonstration of their impact on the bodies hormone system, and cholesterol functioning. This is not a good thing.

For the love of god (and especially your children), eat what you want, but don’t tell people it has magical powers and lets them avoid skin cancer,

Cancer happens all the time, right now at this very second both you and I have cancer cells in our bodies - typically not enough to overwhelm us and we survive (typically). The magical power is keeping the body healthy so immune function is excellent, so that the homeostatic machinery can do its job.

unless you have really solid medical proof from large studies on your side.

https://doi.org/10.1111/joim.12496

Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort

Results Women with active sun exposure habits were mainly at a lower risk of cardiovascular disease (CVD) and noncancer/non-CVD death as compared to those who avoided sun exposure. As a result of their increased survival, the relative contribution of cancer death increased in these women. Nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group, indicating that avoidance of sun exposure is a risk factor for death of a similar magnitude as smoking. Compared to the highest sun exposure group, life expectancy of avoiders of sun exposure was reduced by 0.6–2.1 years.

Conclusion The longer life expectancy amongst women with active sun exposure habits was related to a decrease in CVD and noncancer/non-CVD mortality, causing the relative contribution of death due to cancer to increase.

More sun exposure more cancer, but longer life....... so doing everything with a focus on avoiding all types of cancer may (may) be counter productive. You will note Dr Mason didn't tell you to not use sunscreen, and didn't tell you to stop avoiding the sun, he only talked about vitamin D function and how carnivores report not getting sunburn - it's not a recommendation for behavior.

[–] mech@feddit.org 2 points 7 hours ago (1 children)

The study you linked is about the effect of phytosterols on Vitamin D adsorption from an oral source.
It says nothing about Vitamin D production from sunlight.
And the study involved a single dose of Vitamin D given, to 40 people.

Long term (> 4 weeks) administration of sterols is needed to investigate the impact on Vitamin D absorption and consequently its metabolism.

So the study itself says "for actual evidence, we'd need more data".

[–] jet@hackertalks.com 3 points 7 hours ago

The study you linked is about the effect of phytosterols on Vitamin D adsorption from an oral source. It says nothing about Vitamin D production from sunlight.

The point was to demonstrate plant sterols have a impact on the bodies cholesteral systems including vitamin d production and absorption.

So the study itself says “for actual evidence, we’d need more data”.

Literally every paper ever written says that. We always need more studies, that's the nature of curiosity. In fact professors have to admonish grad students not to add that to papers since its just filler at this point.

I'm not sure what your core thesis is: Vitamin D is not relevant in sun exposure?

https://doi.org/10.1016/j.jid.2017.04.040 -

Oral Vitamin D Rapidly Attenuates Inflammation from Sunburn: An Interventional Study

The diverse immunomodulatory effects of vitamin D are increasingly being recognized. However, the ability of oral vitamin D to modulate acute inflammation in vivo has not been established in humans. In a double-blinded, placebo-controlled interventional trial, 20 healthy adults were randomized to receive either placebo or a high dose of vitamin D3 (cholecalciferol) one hour after experimental sunburn induced by an erythemogenic dose of UVR. Compared with placebo, participants receiving vitamin D3 (200,000 international units) demonstrated reduced expression of proinflammatory mediators tumor necrosis factor-α (P = 0.04) and inducible nitric oxide synthase (P = 0.02) in skin biopsy specimens 48 hours after experimental sunburn. A blinded, unsupervised hierarchical clustering of participants based on global gene expression profiles revealed that participants with significantly higher serum vitamin D3 levels after treatment (P = 0.007) demonstrated increased skin expression of the anti-inflammatory mediator arginase-1 (P = 0.005), and a sustained reduction in skin redness (P = 0.02), correlating with significant expression of genes related to skin barrier repair. In contrast, participants with lower serum vitamin D3 levels had significant expression of proinflammatory genes. Together the data may have broad implications for the immunotherapeutic properties of vitamin D in skin homeostasis, and implicate arginase-1 upregulation as a previously unreported mechanism by which vitamin D exerts anti-inflammatory effects in humans.

Yes, its oral, but it demonstrates that vitamin D is a necessary part of the bodies sun exposure mechanisms. i.e. its produced on demand to treat the damage the sun is doing to the skin.

[–] silly_goose@lemmy.today 2 points 9 hours ago (1 children)

I think the body stops making Vitamin D from the sun when it already has enough to prevent overdose.

So can it really protect you after a certain point?

[–] jet@hackertalks.com 3 points 9 hours ago (1 children)

I think the body stops making Vitamin D from the sun when it already has enough to prevent overdose.

Citation please.

So can it really protect you after a certain point?

The body is all about homeostasis - Carnivores report not getting sunburned after long term adaptation, we don't know the exact mechanisms actually. There is lots of speculation about photosensitizing chemicals, cholesterol function, etc. Regardless of the exact mechanism the thesis is simple: modern eating has a impact on our ability to endure sun exposure and repair damage.

[–] silly_goose@lemmy.today 2 points 9 hours ago* (last edited 9 hours ago) (2 children)

I read on healthline that it's almost impossible to get too much vitamin D from the sun. So I thought the body has to reduce the rate of production at some point when it has enough.

Carnivores report not getting sunburned after long term adaptation

Interesting. Hope they uncover the mechanism soon.

[–] xep@discuss.online 3 points 3 hours ago

There is a possible mechanism. Since melanin increases UV absorption, as you darken due to exposure you will need more exposure to produce the same amount of vitamin D.

[–] jet@hackertalks.com 4 points 9 hours ago* (last edited 9 hours ago)

healthline is not a primary source.

Hope they uncover the mechanism soon.

No money in nutritional approaches to health, so don't hold your breath!

[–] jet@hackertalks.com 3 points 11 hours ago

i would love to see a study on keto vs carnivore sun protective effects

[–] nagaram@startrek.website 0 points 9 hours ago (1 children)

Rule of thumb. Never listen to someone who uses

"Just asking questions"

Rhetoric. They're doing it that way to defend themselves in court or to hide their ignorance.

[–] xep@discuss.online 1 points 3 hours ago (1 children)

When does Dr Mason say that?

[–] nagaram@startrek.website 0 points 2 hours ago (1 children)

"Perhaps vitamin D synthesis in the skin maybe one of those functions."

This isn't a sentence from a place of evidence backed science, this is a string of probably connected things that Dr. Mason should know isn't the same as a proven idea. In fact he says its anecdotal, but he is presenting it in a way that the listener can come to the conclusion that cholesterol makes vitamin D without having to site anything.

If this were a scientifically backed idea he could have said but didn't would follow.

  1. "The Keys survey showed people with higher vitamin D had lower cholesterol."

  2. "A second study was done and found X and Y"

  3. "Thus confirming that cholesterol is used to make vitamin D"

But that isn't what he said. He only cited part of what sounds like a much larger study and is then extrapolating based vaguely on anecdote.

Could it also be possible that people who spend a lot of time in the sun simply consume food with higher vitamin D content and they're in the sum all day because they're mostly agrarian or some sort of labor economy so they're working out which lowers cholesterol levels with a normal diet? Yes, but we don't know more than that based on this talk.

If he's honest, then this is an interesting start point to do science, but as it stands he's just using human psychology to convince people of his position without needing good evidence.

[–] xep@discuss.online 1 points 27 minutes ago* (last edited 12 minutes ago)

Do you see how "perhaps" is different from "just asking questions?"

It is not anecdotal that vitamin D and cholesterol levels in the body are related by the Kandutsch-Russell pathway: https://www.jbc.org/article/S0021-9258(20)41142-1/fulltext

The anecdotal evidence that Dr Mason is referring to is the observed phenomenon that people on the carnivore diet do not sunburn as easily as the people who are not.

Please don't misrepresent the content in this community.