Vitamin D in high latitude animals

[dtilque]

At high latitudes in winter, it’s virtually impossible to get a significant amount of vitamin D from sunlight. So how do animals in high latitudes manage in winter and early spring? Also the same question about nocturnal animals all year around. Where do they get their vitamin D?

The only thing I can think of is that, since Vitamin D is fat soluble, some of it is incorporated in their fat during summer and then is released when the fat is metabolized during winter. But that wouldn’t work for nocturnal animals.

[nearwildheaven]

Animals that get little or no sun exposure (and that would include deep-sea fish) would probably get all the vitamin D they need from their diets.

I’ve seen old pictures of people who lived in the Arctic (IIRC, in Siberia) standing in front of a special lamp, stripped down to their underwear and also wearing safety goggles.

[dtilque]

@nearwildheaven

Animals that get little or no sun exposure (and that would include deep-sea fish) would probably get all the vitamin D they need from their diets.

What plants contain vitamin D? Whenever I see a list of foods high in vitamin D, it never contains any plant foods except those fortified. Yet there are many animals that only eat plants.

[markn_1]

FWIW, both dogs and cats do not produce vitamin D in their skin like humans and some other mammals do, so they must get their vitamin D from diet, no matter where they live. But cats apparently need very little.

DSM Animal Nutrition & Health

[susan]

not all animals are able to get vitamin D from sunshine. This is due either to their physical makeup or the environment in which they live.

…Bottom-dwelling and deep sea fish have no need for synthesizing sunlight into vitamin D, because they are never exposed to the sun. While other fish benefit hugely from UV light and use plasma to process it, this is not where they get their vitamin D. Fish get vitamin D from food, such as plankton, and store it in their livers.

…Reptiles rely heavily on vitamin D. In fact, many reptiles simply cannot function without first basking in the sunlight to warm up and would die if prevented from seeing sunlight.

…Fur covering the skin of an animal…limits the amount of vitamin D absorbed from sunlight. A study on cows conducted at Aarhus University in Denmark found that cows with less fur coverage on the body had more vitamin D-producing plasma after exposure to the sun…

…Although their coverage prevents them from absorbing the UV vitamin D directly, the act of grooming, namely the plucking of feathers and licking of fur, transfers small quantities of vitamin D stored externally into the digestive system, enabling the animals to process vitamin D internally.

Do All Animals Receive Vitamin D From the Sun?

only a few foodstuffs, mainly of animal origin (e.g., fish, meat, offal, egg, dairy), are recommended in literature to be a valuable source of naturally occurring vitamin D-3

Natural Vitamin D Content in Animal Products

However, unlike humans, and other species such as horse, sheep and alpaca, dogs (and cats) ability to synthesise vitamin D is functionally inadequate and so must obtain all its vitamin D from the diet.

OneCup for Horses

[dtilque]

@susan

https://animals.mom.me/animals-receive-vitamin-d-sun-11493.html

You skipped a line from that page that actually answered one of my questions:

Grass and hay is a good vitamin D source

Or at least partially. Are there other plants that are a source of vitamin D? Any of them that humans eat? Also, the thing about grooming being a source: how does the vitamin D get on the animals’ fur or feathers?

[Ruken]

Fungi can synthesize D[sub]2[/sub]; I don’t know if it’s also a photochemical process.

[Northern_Piper]

Have we forgotten the horrors of cod liver oil?

[Nava]

@dtilque

What plants contain vitamin D? Whenever I see a list of foods high in vitamin D, it never contains any plant foods except those fortified. Yet there are many animals that only eat plants.

That depends partly on your definitions. Cholecalciferol, or Vitamin D3, is found in animal sources (and produced on human skin if we get enough light); ergocalciferol, or Vitamin D2, is found in plant sources. Comparison between the two from a nutritional point of view (not sure how good that page is as a source, but all the better-written ones I’ve found were in Spanish).

So if you limit yourself to wanting to look at the exact form humans generate, it’s always going to be animal sources. If you look at the family of molecules with similar activity in the human body, then yes, there’s plants which contain it.

[dtilque]

@Ruken

Fungi can synthesize D[sub]2[/sub]; I don’t know if it’s also a photochemical process.

Based on that site Nava gave, it’s only mushrooms that have grown under UV light. Definitely a photochemical process there. Doing some googling on this, they are apparently the only non-animal humans eat that contains vitamin D. And it looks like there’s a market for UV-exposed mushrooms, for vegans who don’t go outside during the day or live at high latitudes.

So far the list of known vit-D non-animal sources is short: grass and UV-mushrooms. Do we know about any others? I imagine there’s not a lot of research on this, so perhaps not.

[CalMeacham]

There’s a difference between the vitamin D that comes from mushrooms and fungi and the vitamin D from animals – it’s slight, but significant in some cases. They used to make “artificial” vitamin D by irradiating yeast. That vitamin D prevents rickets in humans, but not in chickens.

Mushrooms are actually grown in the dark. If you irradiate those mushrooms with ultraviolet light, you’ll create vitamin D (the yeast kind) by the same process that creates vitamin D in animals. They’re actually doing this commercially, irradiating mushrooms to enhance vitamin D content.
Even if animals have fur, they can still create vitamin. The other way that “artificial” vitamin D is made for the supplement market is by irradiating lanolin. Lanolin is the still sheep exude to keep their wool supple. It’s used as a skin lotion by people. Lanolin also contains the precursor for vitamin D. If you irradiate it with ultraviolet light, it makes vitamin D.

it turns out that sheep get their vitamin D by grooming themselves, thus ingesting the UV-irradiated lanolin. It wouldn’t surprise me if dogs and cats could get vitamin D the same way – both have ur that gets coated with a waxy coating, and both groom themselves relentlessly.

[Colibri]

@dtilque

So far the list of known vit-D non-animal sources is short: grass and UV-mushrooms. Do we know about any others? I imagine there’s not a lot of research on this, so perhaps not.

susan’s link mentions plankton, probably mainly from microalgae.

Fish have the highest natural content of vitamin D expected to derive from an accumulation in the food chain originating from microalgae. Microalgae contain both vitamin D3 and provitamin D3, which suggests that vitamin D3 exist in the plant kingdom and vitamin D3 has also been identified in several plant species as a surprise to many.

[dtilque]

@CalMeacham

There’s a difference between the vitamin D that comes from mushrooms and fungi and the vitamin D from animals – it’s slight, but significant in some cases. They used to make “artificial” vitamin D by irradiating yeast. That vitamin D prevents rickets in humans, but not in chickens.

Yes, it’s D2, which is not as good as D3, but still works for humans. You just need more of it.

Mushrooms are actually grown in the dark. If you irradiate those mushrooms with ultraviolet light, you’ll create vitamin D (the yeast kind) by the same process that creates vitamin D in animals. They’re actually doing this commercially, irradiating mushrooms to enhance vitamin D content.

Yes, that’s what I meant by “there’s a market for UV-exposed mushrooms.” Selling them to vegans who don’t want to consume animal byproducts, but still need it in winter.

Even if animals have fur, they can still create vitamin. The other way that “artificial” vitamin D is made for the supplement market is by irradiating lanolin. Lanolin is the still sheep exude to keep their wool supple. It’s used as a skin lotion by people. Lanolin also contains the precursor for vitamin D. If you irradiate it with ultraviolet light, it makes vitamin D.

it turns out that sheep get their vitamin D by grooming themselves, thus ingesting the UV-irradiated lanolin. It wouldn’t surprise me if dogs and cats could get vitamin D the same way – both have ur that gets coated with a waxy coating, and both groom themselves relentlessly.

OK, that explains the grooming source of vit-D. I was wondering about that.

@Colibri

susan’s link mentions plankton, probably mainly from microalgae.

Thank you. The reference to plankton didn’t identify a plant. As I expect you know (but perhaps others don’t) plankton is a collective term for a wide variety of very small organisms found in water. Microalgae narrows it down considerably and that’s good enough for me.

OK, thanks to everyone who contributed.