Vitamin A is not a single compound but a group of chemical compounds that are structurally similar. These compounds include retinol, retinaldehyde, retinoic acid, and provitamin A caretenoids which include beta-carotene, alpha-carotene, gamma-carotene and cryptoxanthin. Retinol and beta-carotene, are not synonymous, yet are some of the most common forms of vitamin A found in food and supplements, with the former being found in animals and the latter in plants.
Vitamin A is involved in the modulation of energy production, skin health, vision, the immune system, and gene transcription. Different forms of vitamin A will serve different functions. For example, it is retinoic acid that is involved in gene transcription and the maintenance of skin health; it is retinaldehyde that binds certain proteins to the cones and rods of the eye, allowing the eye to function in low-light environments.
Vitamin A is involved in the modulation of energy production, skin health, vision, the immune system, and gene transcription. Different forms of vitamin A will serve different functions. For example, it is retinoic acid that is involved in gene transcription and the maintenance of skin health; it is retinaldehyde that binds certain proteins to the cones and rods of the eye, allowing the eye to function in low-light environments.
The Essential Role of Retinol (Vitamin A): Functions, Benefits, and Differences from Beta-Carotene
Vitamin A is a fat-soluble nutrient critical for numerous physiological functions. While it is often associated with vision, its role extends far beyond eyesight. Retinol, the active form of vitamin A, is essential for cellular health, mitochondrial energy production, immune function, and overall systemic balance. This article will explore the fundamental functions and benefits of retinol, its impact on mitochondria, and how it differs from beta-carotene.
1. Retinol and Energy Production: The Mitochondrial Connection
One of retinol’s most overlooked yet crucial roles is in mitochondrial function and energy metabolism. Mitochondria, the powerhouse of the cell, rely on vitamin A to generate ATP, the body's primary energy currency.
How Retinol Supports Mitochondrial Health
✔ Regulation of Electron Transport Chain (ETC): Retinol influences mitochondrial respiration, ensuring efficient ATP production.
✔ Protection Against Oxidative Stress: It acts as an antioxidant, reducing oxidative damage within mitochondria, which is vital for preventing premature cellular aging.
✔ Enhancing Cellular Respiration: Retinol is involved in the regulation of mitochondrial gene expression, optimizing energy metabolism and reducing metabolic disorders.
✔ Supporting Thyroid Function: The thyroid gland regulates energy metabolism, and vitamin A helps facilitate the conversion of T4 (inactive thyroid hormone) into T3 (active thyroid hormone), directly influencing energy levels.
A deficiency in retinol can result in mitochondrial dysfunction, leading to fatigue, poor cellular repair, and metabolic issues.
2. Immune System Regulation
Vitamin A plays a foundational role in immune function. It supports:
✔ T-cell differentiation – Strengthening adaptive immunity.
✔ Mucosal barrier integrity – Protecting gut lining, lungs, and skin from infections.
✔ Antiviral and antimicrobial defenses – Enhancing immune surveillance against pathogens.
3. Skin Health and Anti-Aging
Retinol is a key ingredient in skincare due to its ability to:
✔ Promote collagen production – Reducing wrinkles and improving skin elasticity.
✔ Regulate keratin production – Preventing conditions like keratosis pilaris.
✔ Accelerate cell turnover – Helping with acne, hyperpigmentation, and scar healing.
4. Eye Health and Vision Support
Retinol is essential for vision as it:
✔ Forms rhodopsin – A pigment in the retina critical for low-light vision.
✔ Prevents night blindness – A classic symptom of vitamin A deficiency.
5. Hormonal Balance and Fertility
✔ Supports reproductive health – Vital for sperm production and fetal development.
✔ Regulates steroid hormones – Influencing estrogen, testosterone, and cortisol levels.
✔ Enhances adrenal function – Improving stress resilience.
6. Bone Health and Growth
✔ Regulates osteoblasts and osteoclasts – Crucial for bone remodeling and repair.
✔ Prevents excessive bone loss – Working synergistically with vitamin D and K2.
While both retinol and beta-carotene are classified as forms of vitamin A, they are fundamentally different in terms of absorption, function, and bioavailability.
A. Bioavailability
✔ Retinol (Active Vitamin A): Found in animal sources such as liver, egg yolks, and butter, it is readily absorbed and utilized by the body.
✔ Beta-Carotene (Provitamin A): Found in plant foods like carrots and sweet potatoes, it must be converted into retinol before the body can use it. However, this conversion is inefficient, with as little as 3% of beta-carotene successfully turning into retinol in some individuals.
B. Genetic Variability and Absorption Issues
✔ Some individuals have genetic variations (BCMO1 gene mutations) that hinder their ability to convert beta-carotene into usable retinol.
✔ Those with gut issues (leaky gut, IBS, SIBO) or poor fat absorption struggle to convert beta-carotene effectively.
C. Function and Storage
✔ Retinol is immediately available for essential biological processes.
✔ Beta-carotene is stored in fat cells and may remain unused if conversion is poor.
D. Overconsumption Risks
✔ Excess beta-carotene can cause carotenemia, leading to an orange skin tint but not toxicity.
✔ Excessive synthetic retinol supplementation can cause toxicity, but natural sources rarely do.
4. Best Sources of Retinol (Active Vitamin A)
To optimize vitamin A intake, prioritize high-quality animal-based foods:
🥩 Beef Liver – The most concentrated source of bioavailable retinol.
🥚 Egg Yolks – Rich in vitamin A and choline.
🧈 Grass-Fed Butter – Contains retinol and other fat-soluble vitamins.
🧀 Raw Cheese – A great source of vitamin A and K2.
🐟 Cod Liver Oil – High in retinol and omega-3s for added anti-inflammatory benefits.
Retinol is a vital nutrient that plays a critical role in mitochondrial energy production, immune health, skin regeneration, hormonal balance, and vision. Unlike beta-carotene, which requires conversion, retinol is immediately bioavailable and essential for numerous bodily functions. Ensuring adequate intake of retinol-rich foods can enhance metabolic efficiency, longevity, and overall vitality.
For optimal health, prioritize whole-food sources of retinol rather than relying on beta-carotene alone.
1. Retinol and Energy Production: The Mitochondrial Connection
One of retinol’s most overlooked yet crucial roles is in mitochondrial function and energy metabolism. Mitochondria, the powerhouse of the cell, rely on vitamin A to generate ATP, the body's primary energy currency.
How Retinol Supports Mitochondrial Health
✔ Regulation of Electron Transport Chain (ETC): Retinol influences mitochondrial respiration, ensuring efficient ATP production.
✔ Protection Against Oxidative Stress: It acts as an antioxidant, reducing oxidative damage within mitochondria, which is vital for preventing premature cellular aging.
✔ Enhancing Cellular Respiration: Retinol is involved in the regulation of mitochondrial gene expression, optimizing energy metabolism and reducing metabolic disorders.
✔ Supporting Thyroid Function: The thyroid gland regulates energy metabolism, and vitamin A helps facilitate the conversion of T4 (inactive thyroid hormone) into T3 (active thyroid hormone), directly influencing energy levels.
A deficiency in retinol can result in mitochondrial dysfunction, leading to fatigue, poor cellular repair, and metabolic issues.
2. Immune System Regulation
Vitamin A plays a foundational role in immune function. It supports:
✔ T-cell differentiation – Strengthening adaptive immunity.
✔ Mucosal barrier integrity – Protecting gut lining, lungs, and skin from infections.
✔ Antiviral and antimicrobial defenses – Enhancing immune surveillance against pathogens.
3. Skin Health and Anti-Aging
Retinol is a key ingredient in skincare due to its ability to:
✔ Promote collagen production – Reducing wrinkles and improving skin elasticity.
✔ Regulate keratin production – Preventing conditions like keratosis pilaris.
✔ Accelerate cell turnover – Helping with acne, hyperpigmentation, and scar healing.
4. Eye Health and Vision Support
Retinol is essential for vision as it:
✔ Forms rhodopsin – A pigment in the retina critical for low-light vision.
✔ Prevents night blindness – A classic symptom of vitamin A deficiency.
5. Hormonal Balance and Fertility
✔ Supports reproductive health – Vital for sperm production and fetal development.
✔ Regulates steroid hormones – Influencing estrogen, testosterone, and cortisol levels.
✔ Enhances adrenal function – Improving stress resilience.
6. Bone Health and Growth
✔ Regulates osteoblasts and osteoclasts – Crucial for bone remodeling and repair.
✔ Prevents excessive bone loss – Working synergistically with vitamin D and K2.
While both retinol and beta-carotene are classified as forms of vitamin A, they are fundamentally different in terms of absorption, function, and bioavailability.
A. Bioavailability
✔ Retinol (Active Vitamin A): Found in animal sources such as liver, egg yolks, and butter, it is readily absorbed and utilized by the body.
✔ Beta-Carotene (Provitamin A): Found in plant foods like carrots and sweet potatoes, it must be converted into retinol before the body can use it. However, this conversion is inefficient, with as little as 3% of beta-carotene successfully turning into retinol in some individuals.
B. Genetic Variability and Absorption Issues
✔ Some individuals have genetic variations (BCMO1 gene mutations) that hinder their ability to convert beta-carotene into usable retinol.
✔ Those with gut issues (leaky gut, IBS, SIBO) or poor fat absorption struggle to convert beta-carotene effectively.
C. Function and Storage
✔ Retinol is immediately available for essential biological processes.
✔ Beta-carotene is stored in fat cells and may remain unused if conversion is poor.
D. Overconsumption Risks
✔ Excess beta-carotene can cause carotenemia, leading to an orange skin tint but not toxicity.
✔ Excessive synthetic retinol supplementation can cause toxicity, but natural sources rarely do.
4. Best Sources of Retinol (Active Vitamin A)
To optimize vitamin A intake, prioritize high-quality animal-based foods:
🥩 Beef Liver – The most concentrated source of bioavailable retinol.
🥚 Egg Yolks – Rich in vitamin A and choline.
🧈 Grass-Fed Butter – Contains retinol and other fat-soluble vitamins.
🧀 Raw Cheese – A great source of vitamin A and K2.
🐟 Cod Liver Oil – High in retinol and omega-3s for added anti-inflammatory benefits.
Retinol is a vital nutrient that plays a critical role in mitochondrial energy production, immune health, skin regeneration, hormonal balance, and vision. Unlike beta-carotene, which requires conversion, retinol is immediately bioavailable and essential for numerous bodily functions. Ensuring adequate intake of retinol-rich foods can enhance metabolic efficiency, longevity, and overall vitality.
For optimal health, prioritize whole-food sources of retinol rather than relying on beta-carotene alone.
Cod liver Oil
Cod liver oil (CLO) is a valuable source of naturally occurring vitamin A (as retinol), which plays an essential role in activating bioavailable copper in order to manage iron in the body. The omega-3s in CLO are also beneficial, but the naturally occurring vitamin A is what we’re really seeking to get. We also get retinol from beef liver and other animal-sourced foods in the ancestral
diet.
Using the chart below, start with a small amount and slowly build up to the full dose. Cod liver oil should ideally be taken with a meal for best absorption, but if that doesn’t work with your schedule, it’s OK to take it separately. When assessing the starting dose for children, use your judgment based on your child’s size and needs. Start small and build up - if they like it and ask for more, they may benefit from steadily increasing. Children are naturally intuitive and will often ask for more when their body likes a nutrient.
Caution:
diet.
Using the chart below, start with a small amount and slowly build up to the full dose. Cod liver oil should ideally be taken with a meal for best absorption, but if that doesn’t work with your schedule, it’s OK to take it separately. When assessing the starting dose for children, use your judgment based on your child’s size and needs. Start small and build up - if they like it and ask for more, they may benefit from steadily increasing. Children are naturally intuitive and will often ask for more when their body likes a nutrient.
Caution:
- Not all cod liver oils are created equal, and processing methods are especially important to consider when selecting one. Ancient traditional practices for purifying cod liver oil for consumption use gentle filtration methods to retain the maximum nutrient value of the oil. Many manufacturers today process their cod liver oil using high temperatures and aggressive purification methods, which degrade the retinol content. They then add in synthetic A & D in order to restore nutrients that were lost during processing. This results in an inferior product that is no longer a whole food. Our recommended brands are vetted to confirm the gentle processing methods that retain the maximum nutrient value of the oil. The ratio of A to D is also important and should ideally be a minimum of 10 to 1 in favor of retinol.
- Be aware that cod liver oil may have a natural propensity to thin the blood.
- Some women opt to stop CLO around two weeks prior to delivery
DOse
Value |
Suggested eventual cod liver oil intake (1 IU retinol = 0.3 mcg RAE) |
Suggested dosing to get optimal intake (based on product values as of Aug 2021) |
Adults▼ (Upper limit across all dietary sources 3000mcg / 10,000 IU of vitamin A) |
Work up to 900mcg / 3,000 IU of vitamin A per day. |
4x jigsaw Health softgels |
Kids▼ (Upper limit across all dietary sources between 600 µg/day or 2000 IU/day (1-2 year olds) through to 2,800 µg/day or 9334 IU/day (14-18 year olds) |
Begins at 400mcg / 1,333 IU (for 1-2 year olds) and increases to 900mcg / 3,000 IU as they age. |
1x Jigsaw Health softgel |
Lactating women▼ (Upper limit across all dietary sources 3000mcg / 10,000 IU of vitamin A) See also CLO caution notes below for pregnant women |
Based on RDI, could build up to 1,300mcg / 4,333IU |
~5x Jigsaw Health softgels |
▼See the US Vitamin A Fact sheets (inc RDAs) or the Australian and New Zealand Reference Values for more
information on measuring retinol, references, etc.
information on measuring retinol, references, etc.
Beef liver
Beef liver provides a balance of copper and iron that is closest to that found in the human liver and is an excellent source of retinol. Beef liver is also a good source of B vitamins, especially B12, and contains intrinsic factor to help with B12 absorption. The emphasis on organically raised, grass-fed, pastured animals is due to the advantage of eating grasses from sun-drenched copper-rich soils that are not depleted due to chemicals. The copper is then passed on to the animal, and eventually, to the consumer.
Begin with a small amount of fresh, organic, pasture-raised and/or grass-fed beef liver, and gradually increase to one 4 - 6 oz. portion per week. Fresh beef liver is considered a superfood due to the concentration of nutrients it contains. Eating it fresh is the optimal means of accessing all the good that this food offers.
An ideal dose is one 4 - 6 oz. (110-170g) serving of fresh beef liver per week. Since liver can be energizing, we suggest taking it earlier in the day, preferably alongside a fatty meal for optimal nutrient absorption, but it’s fine to choose whatever time works best for you.
If beef liver is not available to you, or if you find it too powerful at first, you may start with a small amount of a desiccated undefatted beef liver supplement and slowly work up to enough capsules (or powder) to reach a quantity of 4,000-6,000 mg per day, which is approximately equivalent to one 4-6 ounce serving of fresh beef liver per week. The dosage suggested on the product labels is typically 3,000 mg, so the number of capsules will need to be adjusted accordingly.
For example, if the product label suggests that 4 capsules per day equate to 3,000 mg (or one 3 ounce weekly serving) of fresh liver, it will require 6 capsules per day to equal 4,500 mg (or one 4.5 ounce weekly serving). Each brand may vary on how their dosages are presented, and it may require a look at their website to learn the specifics. Your daily dose of capsules may be spread out between 2-3 meals each day. Once your body has adjusted to the desiccated beef liver supplement, switching to fresh liver is preferred, if available.
Recommended beef liver products: For fresh beef liver, check local grocers, meat markets, or farmers markets to find the best organic, pasture-raised source you can find.
Begin with a small amount of fresh, organic, pasture-raised and/or grass-fed beef liver, and gradually increase to one 4 - 6 oz. portion per week. Fresh beef liver is considered a superfood due to the concentration of nutrients it contains. Eating it fresh is the optimal means of accessing all the good that this food offers.
An ideal dose is one 4 - 6 oz. (110-170g) serving of fresh beef liver per week. Since liver can be energizing, we suggest taking it earlier in the day, preferably alongside a fatty meal for optimal nutrient absorption, but it’s fine to choose whatever time works best for you.
If beef liver is not available to you, or if you find it too powerful at first, you may start with a small amount of a desiccated undefatted beef liver supplement and slowly work up to enough capsules (or powder) to reach a quantity of 4,000-6,000 mg per day, which is approximately equivalent to one 4-6 ounce serving of fresh beef liver per week. The dosage suggested on the product labels is typically 3,000 mg, so the number of capsules will need to be adjusted accordingly.
For example, if the product label suggests that 4 capsules per day equate to 3,000 mg (or one 3 ounce weekly serving) of fresh liver, it will require 6 capsules per day to equal 4,500 mg (or one 4.5 ounce weekly serving). Each brand may vary on how their dosages are presented, and it may require a look at their website to learn the specifics. Your daily dose of capsules may be spread out between 2-3 meals each day. Once your body has adjusted to the desiccated beef liver supplement, switching to fresh liver is preferred, if available.
Recommended beef liver products: For fresh beef liver, check local grocers, meat markets, or farmers markets to find the best organic, pasture-raised source you can find.
references
The Doherty Institute. “Research Reveals Vitamin a Is Key for Regulating Immune Defence in Tissues.” Doherty.edu.au, 12 Nov. 2024, www.doherty.edu.au/news-events/news/research-reveals-vitamin-a-is-key-for-regulating-immune-defence-in-tissues. Accessed 24 Nov. 2024.
Soares-Mota, Márcia. “High Prevalence of Vitamin a Deficiency in Crohn’s Disease Patients according to Serum Retinol Levels and the Relative Dose-Response Test.” World Journal of Gastroenterology, vol. 21, no. 5, 2015, p. 1614, https://doi.org/10.3748/wjg.v21.i5.1614. Accessed 2 Nov. 2020.
Chung, Sanny S. W., et al. “Oral Administration of a Retinoic Acid Receptor Antagonist Reversibly Inhibits Spermatogenesis in Mice.” Endocrinology, vol. 152, no. 6, 19 Apr. 2011, pp. 2492–2502, https://doi.org/10.1210/en.2010-0941. Accessed 26 Aug. 2021.
Masnadi Shirazi, Kourosh, et al. “Vitamin a Supplementation Decreases Disease Activity Index in Patients with Ulcerative Colitis: A Randomized Controlled Clinical Trial.” Complementary Therapies in Medicine, vol. 41, Dec. 2018, pp. 215–219, https://doi.org/10.1016/j.ctim.2018.09.026. Accessed 2 Nov. 2020.
McDaniel, Shauntae M, et al. “Whole-Food Sources of Vitamin a More Effectively Inhibit Female Rat Sexual Maturation, Mammary Gland Development, and Mammary Carcinogenesis than Retinyl Palmitate.” The Journal of Nutrition, vol. 137, no. 6, June 2007, pp. 1415–22, www.ncbi.nlm.nih.gov/pubmed/17513400, https://doi.org/10.1093/jn/137.6.1415.
Lan, Qiu-Ye, et al. “The Association between Dietary Vitamin a and Carotenes and the Risk of Primary Liver Cancer: A Case–Control Study.” Nutrients, vol. 8, no. 10, 11 Oct. 2016, p. 624, www.ncbi.nlm.nih.gov/pmc/articles/PMC5084012/, https://doi.org/10.3390/nu8100624. Accessed 30 Dec. 2019.
Lane, John S., et al. “Nutrition Impacts the Prevalence of Peripheral Arterial Disease in the United States.” Journal of Vascular Surgery, vol. 48, no. 4, Oct. 2008, pp. 897-904.e1, https://doi.org/10.1016/j.jvs.2008.05.014. Accessed 3 Nov. 2021.
Mora, J. Rodrigo, et al. “Vitamin Effects on the Immune System: Vitamins a and D Take Centre Stage.” Nature Reviews Immunology, vol. 8, no. 9, Sept. 2008, pp. 685–698, www.ncbi.nlm.nih.gov/pmc/articles/PMC2906676/, https://doi.org/10.1038/nri2378.
Ceylan-Isık, Aslı, et al. “Cod Liver Oil Supplementation Improves Cardiovascular and Metabolic Abnormalities in Streptozotocin Diabetic Rats.” Journal of Pharmacy and Pharmacology, vol. 59, no. 12, Dec. 2007, pp. 1629–1641, https://doi.org/10.1211/jpp.59.12.0004. Accessed 23 Aug. 2020.
Huang, W. B., Fan, Q., & Zhang, X. L. (2011). Cod liver oil: a potential protective supplement for human glaucoma. International journal of ophthalmology, 4(6), 648.
Brunvoll, S. H., Nygaard, A. B., Ellingjord-Dale, M., Holland, P., Istre, M. S., Kalleberg, K. T., ... & Søraas, A. (2022). Prevention of covid-19 and other acute respiratory infections with cod liver oil supplementation, a low dose vitamin D supplement: quadruple blinded, randomised placebo controlled trial. bmj, 378.
Wang, Zhong-Li, et al. “Dietary Vitamin a Modifies the Gut Microbiota and Intestinal Tissue Transcriptome, Impacting Intestinal Permeability and the Release of Inflammatory Factors, Thereby Influencing Aβ Pathology.” Frontiers in Nutrition, vol. 11, 27 Mar. 2024, https://doi.org/10.3389/fnut.2024.1367086.
Obers, Andreas, et al. “Retinoic Acid and TGF-β Orchestrate Organ-Specific Programs of Tissue Residency.” Immunity, vol. 57, no. 11, 14 Oct. 2024, pp. 2615-2633.e10, https://doi.org/10.1016/j.immuni.2024.09.015. Accessed 5 Feb. 2025.
Soares-Mota, Márcia. “High Prevalence of Vitamin a Deficiency in Crohn’s Disease Patients according to Serum Retinol Levels and the Relative Dose-Response Test.” World Journal of Gastroenterology, vol. 21, no. 5, 2015, p. 1614, https://doi.org/10.3748/wjg.v21.i5.1614. Accessed 2 Nov. 2020.
Chung, Sanny S. W., et al. “Oral Administration of a Retinoic Acid Receptor Antagonist Reversibly Inhibits Spermatogenesis in Mice.” Endocrinology, vol. 152, no. 6, 19 Apr. 2011, pp. 2492–2502, https://doi.org/10.1210/en.2010-0941. Accessed 26 Aug. 2021.
Masnadi Shirazi, Kourosh, et al. “Vitamin a Supplementation Decreases Disease Activity Index in Patients with Ulcerative Colitis: A Randomized Controlled Clinical Trial.” Complementary Therapies in Medicine, vol. 41, Dec. 2018, pp. 215–219, https://doi.org/10.1016/j.ctim.2018.09.026. Accessed 2 Nov. 2020.
McDaniel, Shauntae M, et al. “Whole-Food Sources of Vitamin a More Effectively Inhibit Female Rat Sexual Maturation, Mammary Gland Development, and Mammary Carcinogenesis than Retinyl Palmitate.” The Journal of Nutrition, vol. 137, no. 6, June 2007, pp. 1415–22, www.ncbi.nlm.nih.gov/pubmed/17513400, https://doi.org/10.1093/jn/137.6.1415.
Lan, Qiu-Ye, et al. “The Association between Dietary Vitamin a and Carotenes and the Risk of Primary Liver Cancer: A Case–Control Study.” Nutrients, vol. 8, no. 10, 11 Oct. 2016, p. 624, www.ncbi.nlm.nih.gov/pmc/articles/PMC5084012/, https://doi.org/10.3390/nu8100624. Accessed 30 Dec. 2019.
Lane, John S., et al. “Nutrition Impacts the Prevalence of Peripheral Arterial Disease in the United States.” Journal of Vascular Surgery, vol. 48, no. 4, Oct. 2008, pp. 897-904.e1, https://doi.org/10.1016/j.jvs.2008.05.014. Accessed 3 Nov. 2021.
Mora, J. Rodrigo, et al. “Vitamin Effects on the Immune System: Vitamins a and D Take Centre Stage.” Nature Reviews Immunology, vol. 8, no. 9, Sept. 2008, pp. 685–698, www.ncbi.nlm.nih.gov/pmc/articles/PMC2906676/, https://doi.org/10.1038/nri2378.
Ceylan-Isık, Aslı, et al. “Cod Liver Oil Supplementation Improves Cardiovascular and Metabolic Abnormalities in Streptozotocin Diabetic Rats.” Journal of Pharmacy and Pharmacology, vol. 59, no. 12, Dec. 2007, pp. 1629–1641, https://doi.org/10.1211/jpp.59.12.0004. Accessed 23 Aug. 2020.
Huang, W. B., Fan, Q., & Zhang, X. L. (2011). Cod liver oil: a potential protective supplement for human glaucoma. International journal of ophthalmology, 4(6), 648.
Brunvoll, S. H., Nygaard, A. B., Ellingjord-Dale, M., Holland, P., Istre, M. S., Kalleberg, K. T., ... & Søraas, A. (2022). Prevention of covid-19 and other acute respiratory infections with cod liver oil supplementation, a low dose vitamin D supplement: quadruple blinded, randomised placebo controlled trial. bmj, 378.
Wang, Zhong-Li, et al. “Dietary Vitamin a Modifies the Gut Microbiota and Intestinal Tissue Transcriptome, Impacting Intestinal Permeability and the Release of Inflammatory Factors, Thereby Influencing Aβ Pathology.” Frontiers in Nutrition, vol. 11, 27 Mar. 2024, https://doi.org/10.3389/fnut.2024.1367086.
Obers, Andreas, et al. “Retinoic Acid and TGF-β Orchestrate Organ-Specific Programs of Tissue Residency.” Immunity, vol. 57, no. 11, 14 Oct. 2024, pp. 2615-2633.e10, https://doi.org/10.1016/j.immuni.2024.09.015. Accessed 5 Feb. 2025.
