What are phytoceramides? Do phytoceramide supplements really work to improve aging skin?

I will begin by saying that I have no association with nor will I have any profit from what I'm about to write on the product that I use or don't use.
I've had severe dry skin and allergies my entire life which only increased after menopause. My Functional Doctor told me to use fish oils for my omega 3 fatty acid deficiency (and I have many other deficiencies as well). I used Carlson Labs "The Very Finest Fish Oils" - 1 tsp a day (oral dose)- and within 2 days, I felt a dramatic softening of my skin that shocked me! My skin has never felt this good! I am staying with it! Nothing else has changed except for using that so I am confident to pass this information to you. I was especially pleased when I took a bath and my skin did not dry up afterwards either. Proof that the problem can be corrected when one addresses inner deficiencies rather than slathering on more creams. Some of the driest places on my body was the skin at the base of and between each of my fingers, also the soles and heels of my feet. Those areas look and feels like anyone else's hands and feet now. No cracks, no white areas of flaking and no rough, dried skin. The dried skin scales on my lower legs have nearly all disappeared now and the skin feels soft. I am beyond pleased.

I’d like to add an addendum to my comments:
Use of lotions contains dimethicone just seemed to evaporate on my skin whereas creams tend to give a greasy feel that is quite unpleasant in a humid climate. However, I don’t feel any gooey residue from the CeraVe and when I next shower with plain water I can feel its protective layer still present on my skin. It is quite remarkable. I reiterate that I have no association with CeraVe and this is the first time (if l recall correctly) that l have ever felt that promoting a personal care product might help someone else.

I’m 83 with Crohn’s disease and a history of three ileal ( spell check - small intestine) resections over the past 40 years, resulting in severe malabsorption of nutrients. By closely following CL quality studies, I credit my reasonably decent health to prudent use of a variety of supplements as well as good medical care.
Until l discovered phytoceramide cream and body wash l hated showering and l shed dry skin flakes that wafted all over my house! (I use the brand CeraVe moisturizing cream.) The improvement in my skin is amazing. l will now try an oral supplement as well and I’ll report any changes l notice.
I have no financial or otherwise connection of any sort to the company producing CeraVe.
Thank you ConsumerLab for your very valuable data on the quality of OTC supplements.

I live in the upper Rockies at about 5000’, low humidity. My experience this year switching from Aveeno Daily Moisturizing Lotion (Costco) to CeraVe Moisturizing Cream for a few months was that often by the next morning I was scratching my nose a lot, what I took from occasional experience with cheap lotions over the years to be a sign of dryness (I’m assuming not an allergic reaction, as I don’t have skin problems otherwise except with latex after a few days). Going back to Aveeno, it stopped completely.

I'm a dermatologist who specializes in ceramides and recommends them frequently. I don't have any conflicts of interest. Not sure why you don't mention my favorite studies referenced:

This one confirms, again, that oral ceramides have an effect: https://pubmed.ncbi.nlm.nih.gov/32020853/

This one suggests that systemic ceramides matter for skin: https://pubmed.ncbi.nlm.nih.gov/35199091/

This is more a question.

Wheat Germ Oil and other plant oils (such as Olive & Hemp Oil, etc.) have long been on the market - are these not a source of plant phytoceramides?

I have no problem with people seeking, and supplying, what may (or may not) be a more "pure" or in some cases odorless solution, but if we can use plant oils in out daily eating would this ( does it) supply some, if not all, of the "recommended" dosage?

I never had a dry cell in my body until I reached 60. My hearing aid was itching because of the flaking skin in my ears. I was constantly picking a the build up of flakes. I started taking phytoceramides for my skin and the problem resolved itself.

My son was having to use lots of topical steroids to control his eczema. We figured out he was allergic to the medication. What would we do. He needed some thing to control the eczema. The docs had no answers for us. I did a lot of research and found out about phytoceramides. I started giving them to my son. They work beautifully! He uses them every day and his hands and feet are sooooo much better.

Regarding: "ceramides are waxy lipids naturally found in skin cells which help to regulate the water barrier and water-holding capacity in skin. Decreased levels of ceramides in skin are associated with aging, dry skin, and certain skin conditions, such as atopic dermatitis, eczema and psoriasis."
Is there any evidence that Hot Water/showers/hot tubs decrease the levels of ceramides in our skin. For example, do the elderly in cultures where they don't have excessive amounts of hot water for a lifetime, have higher levels or ceramides in their skin or are the levels consistent with those of us in first world countries that get years of hot water exposure.