Advanced Topic: Radiant Skin Experience

Advanced Topic: Radiant Skin Experience

migraine Consistent with the Undoctored, now Dr. Davis Infinite Health, philosophy, we avoid “treating” health conditions. Instead, we look for factors that allow health conditions to emerge in the first place, address them and, more often than not, the condition reverses or is at least minimized.



The same Undoctored principle applies to skin health and appearance: We get away from notions such as injecting Botox or fillers to smooth skin wrinkles, applying moisturizers that do nothing more than moisturize the external epidermal layer of skin but do nothing for the skin layers below, or applying coverups to conceal skin defects acquired over years. There may be little harm (but a lot of expense!) in engaging in such practices, but they do not address the underlying factors that permit skin aging, sun damage, and development of rashes such as seborrhea and psoriasis.

Just by engaging in all our program strategies, you have adopted extremely powerful practices for skin health. Everyone here is already wheat/grain-free that exerts considerable skin health restoring benefits, including reduction or complete relief from numerous forms of skin rash; vitamin D that provides protection from sunburn and UV damage and improves the skin inflammatory response that can develop from sun exposure; omega-3 fatty acids that make skin fatty acid composition healthier; iodine and thyroid optimization that increases skin moisture; and address microbiome disruptions that help reduce body-wide inflammation because we reduce the endotoxemia of dysbiosis, SIBO, and SIFO that previously inflamed skin. These strategies alone are powerful for restoring and maintaining skin health and achieving radiant skin.

But we can go further. We can address additional disruptions unique to modern lifestyle such as:

  • Loss of the intestinal microbial species Lactobacillus reuteri that exerts dramatic skin benefits by triggering increased release of the hormone, oxytocin, via the gut-brain axis and thereby increases skin collagen and skin thickness.

  • Failure of the modern diet to provide collagen from organ meats such as heart, tongue, stomach, and intestines

  • Failure of the modern diet to provide hyaluronic acid, obtained from the same foods that contain collagen

  • Failure of the modern diet to provide abundant carotenoids

We have the option to therefore address all four of these factors for even greater skin health and appearance benefits such as increased moisture, increased flexibility, increased protection from sun exposure, partial reversal of sun damage, and reduction of skin wrinkles.

We therefore propose a regimen that any adult can follow that, in addition to skin health and appearance benefits, also yields substantial benefits in joint health (increased joint cartilage, increased joint glycosaminoglycan joint lubricant), arterial health, can reduce blood pressure modestly, even yield effects on preserving cognitive health. Be sure to document your experience by obtaining photos (“selfies”) before the start, then after 90 days and feel free to share with our Undoctored community.

Basics of Skin Structure

Our discussion on effects on skin will be easier to follow if you understand just a little about skin anatomy.

From the exterior down, skin is comprised of three layers: the epidermis that is the outer protective layers that we all view on the surface of your face, shoulders, legs, and elsewhere; the dermis below the epidermis that hosts most of the skin’s collagen and fibrin structural tissues, hyaluronic acid, immune cells, and blood vessels; the hypodermis that is composed mostly of fat and provides a cushioning and insulating function.


With aging, we lose collagen and hyaluronic acid, collagen fibers are degraded by enzymes such as matrix metalloproteinases, and the epidermal and dermal layers become thinned, viewed externally as fine wrinkles, large wrinkles, and “crepey” dry skin. The Four Components of the Dr. Davis’ Infinite Health Radiant Skin Experience:

L. reuteri

The majority of people have lost important bacterial species from their intestinal microbiomes due to factors such as antibiotic use, exposure to herbicides and pesticides in food, various pharmaceutical agents, emulsifying agents in foods, synthetic sweeteners, and other factors. Among the species lost by most people in the Western world is Lactobacillus reuteri. By one estimate, 96% of Westerners have lost this microbe from their intestinal microbiomes, despite its ubiquitous presence in both extant hunter-gatherer human populations and most mammalian species. Supplementation of this bacterial species to experimental animals has been found to provoke release of the hormone oxytocin from the hypothalamus and pituitary glands via the “gut-brain axis,” i.e., an effect mediated via retrograde signaling via the vagus nerve to the hypothalamus and pituitary glands in the brain, with effects that include suppression of appetite, increased muscle mass, but also with substantial effects on skin including a marked increase in dermal collagen, increased skin thickness (epidermis + dermis), 50% reduction in healing time after purposefully inflicted skin wounds, and increased sebum production. Limited human clinical trial experienced has likewise demonstrated acceleration of healing. Our real-world experience with L. reuteri yogurt that yields bacterial counts of 200-260 billion bacteria per 1/2-cup serving has also borne out these effects for most people.

Marine-sourced collagen hydrolysates

Collagen is a natural structural protein contained throughout the body but concentrated in skin, especially the dermal layer. 70% or more of the dry weight of human skin is comprised of collagen. Oral collagen hydrolysate supplementation, i.e., supplementation of animal-derived collagen hydrolyzed, or broken down, via acid/base and enzymatic reactions, has been shown in human clinical trials to stimulate migration and growth of fibroblasts in skin that, in turn, increase production of dermal collagen. Production of hyaluronic acid by fibroblasts is also increased (see below). Accumulation of collagen peptides in skin also reduces activity of skin enzymes such as matrix metalloproteinases that degrade collagen.

Marine-sourced collagen hydrolysates, in particular, have been demonstrated to be as effective as bovine- or porcine-sourced collagen hydrolysates but at lower doses of compared to doses required with collagen from bovine, porcine, and chicken sources. Efficacy at lesser doses has been attributed to greater concentrations of the Gly-Pro-Hyp tripeptide and the Gly-Pro and Pro-Hyp dipeptides, with concentrations that vary among different species of fish sources (e.g., bony vs. cartilaginous), as well as inclusion or exclusion of skin. Radioactively-tagged Gly-Pro-Hyp tripeptides and Pro-Hyp dipeptides have been shown to be deposited in skin, primarily the dermal layer where it takes up long-term residence. It has been determined that these peptide fractions are largely responsible for the dermal and skin effects of collagen hydrolysates. Human clinical trials have demonstrated that marine collagen hydrolysates increase dermal thickness, improve collagen organization, increase skin elasticity, increase skin moisture, and reduce wrinkle depth, including periorbital “crow’s feet” and the nasolabial fold, at doses ranging from 500 mg to 10 grams, typically visible starting after 8-12 weeks. The form of marine collagen hydrolysates we have chosen has been shown to be effective at a daily dose of 2.5 grams.

Hyaluronic acid

Hyaluronic acid is a natural component of numerous organs of the body but especially skin. Like collagen, hyaluronic acid is concentrated in the dermal layer and is extremely effective at maintaining moisture content, being able to hold many times its weight and volume in water. With aging, there is gradual but dramatic loss of hyaluronic acid such that, by age 70, 75-90% of collagen present in youthful skin is lost that results in reduced skin moisture and reduced smoothness.

HA and skin aging
(Gollner 2017)

While hyaluronic acid has an extensive track record of safety through administration via topical and injectable means (as skin “filler,” as well as into joints such as the hip and knee for arthritis pain, in which hyaluronic acid suffers from yielding only temporary effects), it can also be administered orally with clinically demonstrated effects on increasing dermal collagen production, increased hyaluronic acid content of the dermal layer, and increased skin moisture. Because effects only persist for several days after consumption, we supplement hyaluronic acid daily.


Astaxanthin is a carotenoid, related chemically to beta-carotene, lutein, and other carotenoids, sourced from orange- or red-colored shells of crabs, lobster, shrimp, as well as salmon and algae (Haematococcus pluvialis). Unlike other carotenoids, astaxanthin is not metabolized to vitamin A.

In several human clinical trials, orally administered astaxanthin has been demonstrated to reduce and reverse sun-damaged skin and reduce the impaired immune response provoked by excessive sun exposure. Orally consumed astaxanthin has been shown to accumulate in skin. Astaxanthin exerts 40- to 100-fold greater in vitro anti-oxidative activity compared to beta-carotene and thereby has greater effects on reducing oxidative damage in the skin triggered by ultraviolet (UV-A) wavelength of light from sun exposure. Astaxanthin has also been shown to increase skin moisture, increase skin flexibility, and reduce skin wrinkle depth.

                       Beta-carotene                                                 Astaxanthin

Excessive sun exposure increases the expression of inflammatory cytokines such as IL-1?, IL-6, and TNF-? that upregulate activity of several matrix metalloproteinase enzymes that degrade collagen and elastin fibers residing in skin, effects that lead to wrinkle formation and loss of skin elasticity and moisture. Astaxanthin consumed orally has been demonstrated to subdue or block these effects.

Human absorption of astaxanthin ranges from 6% to 34% after 4 hours and the elimination half-life ranges from 16 to 30 hours. Absorption is enhanced when orally consumed in the presence of dietary lipids. It therefore helps to take your astaxanthin preparation with an oil- or fat-containing meal (olive oil, butter, coconut oil, eggs, avocado, meats, etc.).

Eight human clinical trials of orally administered astaxanthin (2-8 mg/day) have been conducted, 4 of which were placebo-controlled, in which reduction of skin wrinkles, erythema, and age spots were documented along with increased elasticity and moisture, decreased matrix metalloproteinase activity.

Proposed regimen:

L. reuteri yogurt: 1/2-cup per day, providing approximately 260 billion colony-forming units (CFUs)

Suggested L. reuteri Source: Inner Circle L.reuteri recipe

Collagen hydrolysates: 2.5 grams per day of marine-sourced, 10 grams per day if bovine or porcine

Suggested Collagen Source: Nature’s Bounty, Collagen Beauty Blend 

Hyaluronic acid (high-molecular weight): 120 mg per day

Suggested Hyaluronic Acid Source: Natural Factors, Hyabest Hyaluronic Acid

Astaxanthin: 4 mg per day with oil- or fat-containing food

Suggested Astaxanthin Source: NOW Supplements, Astaxanthin

To document skin changes, we suggest that you obtain facial photos (“selfies”) in the same lighting conditions pre- and 90 days post-, i.e., similar sun conditions/time of day, same location, avoid use of makeup at time of photo, remove eyeglasses and sunglasses, etc.

Selected references:

L. reuteri and oxytocin
Poutahidis T, Kearney SM, Levkovich T et al Microbial symbionts accelerate wound healing via the neuropeptide hormone oxytocin. PLoS One 2013 Oct 30;8(10):e78898.

Erdman SE, Poutahidis T. Probiotic 'glow of health': it's more than skin deep. Benef Microbes 2014 Jun 1;5(2):109-19.

Varian BJ, Poutahidis T, DiBenedictis BT et al. Microbial lysate upregulates host oxytocin. Brain Behav Immun 2017 Mar;61:36-49.

Cho SY, Kim AY, Kim J et al. Oxytocin Alleviates Cellular Senescence through Oxytocin Receptor-Mediated ERK/Nrf2 Signalling. Br J Dermatol. 2019 Feb 22.

Collagen hydrolysates
Kim DU, Chung HC, Choi J, Sakai Y, Lee BY. Oral Intake of Low-Molecular-Weight Collagen Peptide Improves Hydration, Elasticity, and Wrinkling in Human Skin: A Randomized, Double-Blind, Placebo-Controlled Study. Nutrients. 2018 Jun 26;10(7):826.

Sugihara H, Inoue N, Wang X. Clinical effects of ingesting collagen hydrolysate on facial skin properties—A randomized, placebo-controlled, double-blind trial. Jan Pharmacol There 2015;43(1):67-70.

Campos P, Franco R, Kekuda L et al. Oral supplementation with hydrolyzed fish cartilage improves the morphological and structural characteristics of the skin: a double-blind, placebo-controlled clinical study. Molecules 2021; 26(16):4880.

Sangsuwan W, Asawanonda P. Four-weeks daily intake of oral collagen hydrolysate results in improved skin elasticity, especially in sun-exposed areas: a randomized, double-blind, placebo-controlled trial. J Dermatolog Treat. 2020 Mar 9:1-6.

Czajka A, Kania EM, Genovese L et al. Daily oral supplementation with collagen peptides combined with vitamins and other bioactive compounds improves skin elasticity and has a beneficial effect on joint and general wellbeing. Nutr Res. 2018 Sep;57:97-108.

Proksch E, Segger D, Degwert J et al. Oral supplementation of specific collagen peptides has beneficial effects on human skin physiology: a double-blind, placebo- controlled study. Skin Pharmacol Physiol 2014;27:47–55.

Hyaluronic acid
Göllner I, Voss W, von Hehn U, Kammerer S. Ingestion of an Oral Hyaluronan Solution Improves Skin Hydration, Wrinkle Reduction, Elasticity, and Skin Roughness: Results of a Clinical Study. J Evid Based Complementary Altern Med 2017;22(4):816-823.

Hsu TF, Su ZR, Hsieh YH, Wang MF, Oe M, Matsuoka R, Masuda Y. Oral Hyaluronan Relieves Wrinkles and Improves Dry Skin: A 12-Week Double-Blinded, Placebo-Controlled Study. Nutrients. 2021 Jun 28;13(7):2220.

Kawada C, Yoshida T, Yoshida H, Matsuoka R, Sakamoto W, Odanaka W, Sato T, Yamasaki T, Kanemitsu T, Masuda Y, Urushibata O. Ingested hyaluronan moisturizes dry skin. Nutr J. 2014 Jul 11;13:70.

Tominaga K, Hongo N, Fujishita M, Takahashi Y, Adachi Y. Protective effects of astaxanthin on skin deterioration. J Clin Biochem Nutr. 2017 Jul;61(1):33-39.

Tominaga K, Hongo N, Karato M, Yamashita E. Cosmetic benefits of astaxanthin on humans subjects. Acta Biochim Pol. 2012;59(1):43-7.

Mercke Odeberg J., Lignell A., Pettersson A., Höglund P. Oral bioavailability of the antioxidant astaxanthin in humans is enhanced by incorporation of lipid based formulations. Eur. J. Pharm. Sci. 2003;19:299–304.

Singh KN, Patil S, Barkate H. Protective effects of astaxanthin on skin: Recent scientific evidence, possible mechanisms, and potential indications. J Cosmet Dermatol. 2020 Jan;19(1):22-27.