Vitamin A

Vitamin A

Is vitamin A really a vitamin?

Plant sources of retinoids

Limiting digestion of plant retinoids

Animal sources of retinoids

Other sources of retinoids

Symptoms of acute vitamin A toxicity

Symptoms of chronic vitamin A toxicity

How did widespread toxicity happen?

Grant Genereux's vitamin A elimination diet

Other possible ways to reduce stored retinol

References

Vitamin A

Vitamin A is renowned as a fat-soluble group of essential micronutrients. The conventional wisdom, from Wikipedia and many studies, is that vitamin A is essential for growth during embryo development, maintaining the immune system, and healthy vision.

Vitamin A is stored in the form of retinol in the liver. If the storage capacity of the liver is exceeded, retinol is stored in fat cells around the body. Retinol is tightly held in the liver and fat cells, and once accumulated it is difficult to get rid of.

Most vitamin A occurs in animal-based foods in the form of retinoids that are efficiently absorbed in the digestive tract.

Vitamin A also occurs in plants in the form of carotenoids, most notably beta-carotene. Carotenoids are a provitamin (precursor) that the animal consuming the plants converts to retinol. This conversion of the carotenoids in plant foods is regulated by factors such as the amount of retinol already stored in the liver and other parts of the body; the food source; the type of carotenoid; whether fat is consumed with the carotenoid; and the health of the gut.

The Recommended Daily Allowance for vitamin A is 900 ug/day for men and 700 ug/day for women. This translates to 3,000 IU per day for men and 2,333 for women. An upper limit of 3,000 ug/day or 10,000 IU is suggested for both men and women. (25)

Is vitamin A really a vitamin?

Grant Genereux wrote a number of articles suggesting that Vitamin A is not a vitamin because it does not fit the definition of a vitamin. Tiny amounts of retinoic acid are used by the immune system, but any excess is toxic, corrosive and difficult to decompose and excrete. He could find little evidence that the various forms of vitamin A are beneficial in any quantity, even though nearly all the literature and studies proclaim that vitamin A is an essential nutrient.

Carotenoids and vitamin A from food convert into various retinoids and finally into retinoic acid. Retinoic acid is used by the immune system to destroy pathogens and damaged or infected cells. Retinoic acid acts like venom, and only tiny quantities are required for this task. If cells start generating retinoic acid from excess retinol this causes a massive immune response, widespread inflammation, and a variety of idiopathic (inexplicable) diseases. (4, 5)

The level of vitamin A in a traditional diet does not normally cause problems with the liver or other parts of the body. The human body is well adapted to dealing with this toxin on a daily basis, but only in small amounts. We are now loading ourselves up with vitamin A like never before in human history.

Vitamin A or its betacarotene precursor is in nearly every modern food in one form or another. Since the 1970s the modern human diet has evolved towards foods with a high vitamin A concentration. Oily cold water fish and low fat dairy products are widely consumed by misinformed health-conscious people. Modern Franken-fruits and Franken-vegetables contain abundant levels of brightly-coloured carotenoids, and they are available year round. Not too long ago, these foods were seasonal heritage produce, not yet bred for the demands of supermarkets.

When vitamin A is needed by any cells around the body, it is released by the liver in the form of bound retinol. The liver does this by first wrapping the retinol in what is called retinol binding protein. Think of the RBP as an envelope that facilitates the safe transfer of retinol in the blood serum. When encased within the RBPs, no part of the vitamin A molecule is exposed to the outside world. In this packaging, it is harmless and may even be useful. All cells have RBP receptors on their membrane. The cells that request the retinol enable their RBP receptors, thereby ensuring that the retinol is only received at the correct destinations.

If vitamin A consumption exceeds the quantity used by the body, eventually the liver will reach storage capacity. The skin, fat, and intestine are secondary storage locations. This can take years depending on how much vitamin A is consumed. When the liver is "full" retinoids in excess of needs overflow and are released as unbound retinol. At first, this unbound retinol is stored in fat around the body, which buys some time. Eventually some of the retinol may not be stored in fat, or may be released from fat if the fat is used as an energy source. It may also be stored in other organs like the skin, lungs, kidneys, GI tract and joints. This unbound retinol converts to retinoic acid that is extremely harmful to cells and organs. (7) If your daily intake of vitamin A continues to exceed your body's daily usage, serious consequences are inevitable. (7)

"Hepatic storage of vitamin A will continue until a pathologic liver condition develops." (5)

"The current safe uptake rate from food is going to be a very personal number based upon age, and their lifetime's history of particular dietary habits, etc. It is, therefore, proportional and completely unknown." (1, page 402)

If you are showing symptoms of vitamin A overload you might assume that it is easy just to cut back on foods that contain vitamin A. However, the vitamin A in your liver is trapped there, possibly for many years. The same applies to the vitamin A stuck in your skin and other organs. Leftovers from the immune response such as cytokines and antibodies may also remain stuck in your skin.

In the USA, people from higher socioeconomic groups have a higher incidence of autoimmune diseases, MS, Lupus, Crohn's and Alzheimer's. It is probably because they are likely to be more educated and have more money to spend on eating healthy with lots of brightly coloured fruits and vegetables, and they probably take vitamin supplements.

Genereux shows a high correlation between oily fish consumption and many diseases. Finland has high fish oil consumption, Russia has low consumption. Although these two populations are close to each other, Finland's incidence of Alzheimer's and dementia is 25 times higher than their immediate neighbour. (1) The same applies with diabetes, MS, and eczema.

Plant sources of retinoids

Many plants are high in carotenoids like beta-carotene. Few if any plants contain actual retinoids (retinol, retinal, retinoic acid, and their esters) but plant carotenoids can be converted into retinoids. However, the body regulates beta-carotene conversion to retinoids, preventing toxicity from plant sources, as noted by the Linus Pauling Institute. (21)

The most concentrated sources of carotenoids like beta-carotene are brightly coloured fruits and vegetables. Here are the highest sources:

1. Hot chilies and cayenne pepper.
2. Sweet potatoes, particularly orange and yellow varieties.
3. Yams.
4. Yellow and red capsicums (sweet or bell peppers).
5. Gac fruit, a bright orange Asian fruit.
6. Mangoes, paw paw (papaya), apricots, cantaloupe, peaches, nectarines, guava, tangerine, orange, persimmon, strawberries and other berries.
7. Tomato, orange-coloured carrots, sweet or neutral leafy greens like spinach, kale, lettuce, beet greens, collard.
8. Spices and herbs. Many but not all contain carotenoids. The highest concentrations are found in cayenne pepper, chili, paprika, nigella, and dried marjoram, sage, basil, thyme and oregano. Those with no or little carotenoids include black and white pepper, ginger, turmeric, cinnamon, cloves, nutmeg, cardamom, mace, bay leaves, peppermint, tarragon, dill, chervil, and rosemary. Seeds with little or no carotenoids include caraway, cumin, fennel, anise, coriander, dill, mustard, poppy and celery.
9. Many other plants contain smaller quantities of carotenoids.

Limiting digestion of plant retinoids

Numerous factors influence how much of the plant carotenoids consumed are converted into retinols, such as what other foods they are consumed with, the digestive health of the person eating them, and whether the body's stores of retinoids are already high so less carotenoids are converted.

Probably only a small proportion of the total carotenoids consumed are converted to retinoids, but there are many unknowns and a lack of research on this topic. (21)

Carotenoids are converted to retinoids like retinol and retinoic acid, mainly by enzymes in the small intestines and liver.

Beta-carotene is the most efficiently converted carotenoid. Alpha-carotene and beta-cryptoxanthin have lower conversion rates. Lutein, zeaxanthin, and lycopene are generally not converted. (21) Foods high in lutein and zeaxanthin include kale, spinach, Swiss chard, collard greens and dandelion greens. Foods high in lycopene include tomatoes, pink guava, watermelon and pink grapefruit. Unfortunately most of these foods are also high in beta-carotene, so only a strict vitamin A elimination diet will avoid all of them.

Some carotenoids pass straight through the digestive tract without being converted, because of the other foods that they are combined with. There are no published studies on this issue, but some widespread traditions are revealing.

Chili peppers and chili powder are widely used in Indian cooking. Chilies have about 30,000 IUs of vitamin A per 100 grams. Sweet potatoes and other high carotenoid fruits and vegetables are also popular in Indian cuisine. A food preparation rule handed down over the centuries is that chilies must never be combined with dairy milk. Chilies in a meal without milk or any other dairy products are fine. However if chilies and dairy products are combined it will make you very ill. Grant Genereux suggests that milk protein (casein) acts as a carrier molecule that transfers the carotenoids in the chili across the intestinal wall. (1)

Cooking, especially with fat, enhances the digestion of carotenoids. Try to eat raw rather than cooked plants because the carotenoids in raw plants are less bioavailable.

Bitter leaves decrease carotenoid digestion. Bitter leaves include many plants that are considered weeds, such as nettles, blackjack, sour thistle and many other edible weeds. Include bitter leaves in your salads and combine them with high carotenoid plants. Green tea leaves and tobacco leaves are also bitter leaves that humans have used for centuries.

Alcohol consumption may inhibit the conversion of carotenoids into retinoids by competing for aldehyde dehydrogenase enzymes. Some carotenoids are absorbed into the blood and transported to tissues where they may act as antioxidants and then broken down and excreted in the faeces, or through the skin as sebum or sweat. In cases of high carotenoid digestion, a visible yellowing of the skin can occur due to carotenoid deposition in the epidermis.

Animal sources of retinoids

1. Liver and kidneys. Liver is a highly concentrated source of retinoids. Regular consumption of liver may cause serious conditions like cancers, bone deformation and dental deformation. Eating even small quantities of the liver of several carnivores such as polar bears is fatal.
2. Cod liver oil.
3. Oily fish like cod, salmon, mackerel, herring, tuna and sardines. Atlantic cod has ten times more vitamin A more than Pacific cod. The deeper and colder water increases retinoid concentration. (3) Interestingly, Australia's Barramundi fish, a delicious oily-fleshed fish, has little to no vitamin A content. This is probably because they only occur in rivers and shallow warm coastal waters.
4. Dairy products, especially low fat dairy products. Worse, vitamin A is mandated to be added to milk in the USA, Canada, China and Costa Rica. India is considering doing this as at 2025.
5. Butter contains vitamin A, but when used moderately the harm from the retinoids may be offset by the protective effects of the high quality fats it provides. Butter should be eliminated when on the vitamin A elimination diet.
6. Egg yolk.
7. Poultry, particularly dark meat with skin.

Other sources of retinoids

Sunscreens. Various synonyms for retinols are used on product labels: all-trans-retinyl, palmitate; retinol palmitate; retinol hexadecanoate; retinyl palmitate; vitamin A palmitate are all referring to the same molecule. They cause cancers. (16)

Personal products. Skin creams, plasters, wipes and pills may contain the same retinols listed above for sunscreens. Retinyl palmitate is water soluble, making it easy to add to products that don't contain oils.

Factory foods. Many ready-to-eat cereals are "fortified" with vitamin A. Skim and low-fat milk are frequently "fortified" with vitamin A, as is margarine. Plant-based milk alternatives like soy, almond or oat milk, and fortified orange juice may have added vitamin A.

Symptoms of acute vitamin A toxicity

• Abdominal pain.
• Birth defects.
• Drowsiness, irritability.
• Enlarged and fatty liver.
• Nausea and vomiting.
• Elevated pressure around the brain, headaches.

Symptoms of chronic vitamin A toxicity

• Idiopathic diseases. These are diseases for which the cause is unknown according to conventional allopathic medicine. Many modern diseases are idiopathic, raging at epidemic levels, with systemic inflammation associated with most of them. Some doctors suggest allergies may be the root cause, but lengthy elimination of trigger foods, dust, pollen, mites and so on do not provide a cure. A consistent explanation for these widespread diseases is vitamin A.
• Autoimmune diseases. There are about 80 different documented autoimmune diseases. They include Crohn's, IBD, Eczema, Psoriasis, Rheumatoid Arthritis, Juvenile Rheumatoid Arthritis, Graves', Hashimoto's, Lupus, Sjogren's syndrome, Type I diabetes, Celiac and Multiple Sclerosis. Very few people get just one of them. They all have systemic Inflammation in common.
• Damaged immune system. Slow healing of injuries, high rate of infections, systemic inflammation.
• Inflammation. Endless inflammation, widespread, repeatedly thinking you have found the root cause and then being disappointed.
• Cytokine-induced apoptosis. This occurs when killer-cell activity is over-stimulated by retinoic acid, leading to inflammation, fever, fatigue, digestive and neuropsychiatric problems. (13)
• Skin. Eczema, even in newborns, oily skin - dry skin cycles, rough dry flaky itchy or peeling skin, age spots (liver spots), skin cracks at the corners of the mouth, peeling or shedding of the skin, often in sheets or scales (desquamation). (6)
• Jaundice is probably a protective action taken to emulsify circulating retinoids with bilirubin. This should be distinguished from excess carotenoids in the diet that are directly stored in the skin, also making it a yellow colour.
• Hair. Alopecia (hair loss), oily hair - dry hair cycles, grey to white hair.
• Nails. Cracked fingernails.
• Pregnancy. Compromised foetal development, foetal abnormalities, and birth defects. (18)
• Bones. Osteoporosis, weak bones even in children, swelling, pain, joint pains, back pain. (8)
• Calcium deposits, hypercalcemia as spurs, osteo-arthritis, and kidney stones. (8)
• Teeth and gums. Gingivitis, periodontitis, mouth ulcers, cheilosis (fissures in the corners of the mouth).
• Brain, nerves. ADHD, Alzheimer's, anxiety, autism, brain fog, dementia, depression, headaches, lack of coordination, Lou Gehrig's disease, MS, schizophrenia and vertigo may be variations of one big spectrum. What if ADHD is just very mild autism, and depression is just one of the symptoms of mild schizophrenia, and anxiety is just a small variation of ADHD combined with depression, and schizophrenia is early Alzheimer's, and therefore, Alzheimer's is the long tail condition of dealing with autism or mild schizophrenia for decades? Could it be that all of these diseases are just varying degrees of the same underlying root cause?
• Eyes. Ailments including glaucoma, macular degeneration, dry eyes, blurry vision, double vision or other visual changes. Cataracts. Sensitivity to sunlight.
• Heart. Coronary heart disease, palpitations, abnormal blood tests, hypertension, blood clots, embolism, stroke, heart attack.
• Digestive tract. Gastrointestinal problems including oesophageal constriction, Crohn's disease, celiac disease, gluten sensitivity, IBS, colitis, nausea, vomiting, poor appetite.
• Diabetes, insulin resistance.
• Obesity.
• Liver. Enlarged and fatty. High levels of vitamin A can displace iron from the liver. (12)
• Oedema (edema). Swelling of the hands and feet.
• Insomnia. Rarely or never dreaming.
• Chronic fatigue.
• Cancers. (16)
• Muscle aches and pain.
• Lungs. Asthma, respiratory infections, pneumonia, cysts and lesions, cancers.

How did widespread toxicity happen?

Usually it takes many years before vitamin A toxicity symptoms occur, sometimes a lifetime. However, people are both wealthier and more health credulous than fifty years ago. Foods like tomatoes, sweet potatoes, all kinds of peppers and capsicums, mangoes and coloured tropical fruits, and oily cold water fish are available all year round. The current (bad) nutritional advice is to consume lots of milk, dairy, brightly coloured fruits and vegetables every day. Liver is advised as the richest source of animal nutrients. Cod, especially cold water cod, is recommended. The rate of vitamin A toxicity has increased exponentially.

Women get vitamin A-excess diseases at a rate 2-4 times more than men. (1, page 316) It is probably because they eat more fruits and coloured salads, and want to provide a good nutritional example to their children.

It is almost impossible to measure the level of vitamin A stored in the body, because nearly all of it accumulates in the liver. The only reliable test is a liver biopsy, performed using a thick biopsy needle. Usually this is only done on dead people, because the trauma on a live person is significant.

The combination of multiple year delays between the consumption of vitamin A and the symptoms, and the difficulty of measuring vitamin A levels has meant that doctors and researchers have not realised that so many modern diseases, especially autoimmune diseases, all have the same root cause.

Grant Genereux's vitamin A elimination diet

Three days after starting his elimination diet, Genereux notice decreased inflammation, and after a month significant overall improvements except with his eczema. He says that he is still improving his skin and other factors nine years after starting his vitamin A elimination diet. Clearly full recovery and healing is a very slow process.

He estimates that a vitamin A free diet will reduce total body vitamin A stores by approximately 0.5 percent per day in adults. In other words, after about 200 days on a vitamin A elimination diet, the body would be largely free of it. (20)

The vitamin A elimination diet:

• Lots of water.
• White or brown rice (not yellow or golden rice).
• Beef (steak, roast, no sauces or spices other than salt and trace amounts of white pepper if wanted). Occasional turkey breast or lobster for variety.
• Kidney beans.
• Olive oil (max of 1 teaspoon per day). No butter or coconut oil.
• Black coffee if wanted (no milk, cream or whiteners).
• Zinc, Vitamin C, and B supplements except niacin.

"I occasionally included some applesauce, pineapple, raisins, milled flaxseed, and a few almonds. These can help with fibre, provide vitamin C, E and make an otherwise dry rice and beef meal quite delicious too. However, it is critically important not to overdo it on the olive oil or almonds. Both are quite high in vitamin E, and this too can become toxic at too high a level. Vitamin E is also documented to cause an increase in serum vitamin A levels. This elevated risk is because the body is now reaching its capacity for storing any of the fat-soluble vitamins in general."

"In the very late stages of my recovery, I added bone broth soup. Go to near zero vitamin A consumption for say three months, and then very low after that."

For inflamed skin use Preparation H with Biodyne. This is an old remedy for haemorrhoids, but works well to relieve eczema.

Other possible ways to reduce stored retinol

• Fasting. One day dry fast each week, followed by one week of beef only.
• Anorexia. Fat disappears, along with the vitamin A stored in it. It is not clear what happens to the retinol as it is released from the fat and whether it does any damage prior to being eliminated. Genereux provides anecdotes (1) that some people with dementia stop eating days or weeks before they die. In their final days they return to having periods of lucidity. When Ronald Reagan was dying from Alzheimer's he also had severe cataracts. His eyes were completely clouded over. Apparently in his final days after he had stopped eating, his eyes cleared and were blue once again.
• Fever, infections. Infectious diseases deplete stored retinol. (9) We need constant exposure to bacteria and other microbes so that the immune system creates retinoic acid from stored retinol. Exercising our immune systems by having them fight invaders such as measles or mumps may be a good thing. Hygiene is associated with Alzheimer's disease, among many other diseases. (10)
• Hygiene has degraded the environment the immune system evolved to deal with. The immune cells no longer need to use up significant amounts of retinol to kill bacteria and other pathogens on our skin and in our gut. In a "normal" dirty environment the immune system used enough circulating retinol to prevent a build-up of vitamin A in the liver and fat. This lack of hygiene, quite counter-intuitively, was a very good thing.
• Healthy mouth and gut biome. Repopulate bacteria in the gut if suffering from IBS or other gut issues by using probiotics, prebiotics, a faecal microbial transplant, and the reestablishment of key foundation bacteria like Lactobacillus reuteri, L. gasseri, and Bifidobacterium infantis.
• Baking soda. Sodium bicarbonate can neutralise circulating retinoic acid, as in the following reaction: RCOOH + NaHCO3 -> RCOONa + H2O + CO2. A daily dose of baking soda may help reduce the destructive inflammation of autoimmune diseases like rheumatoid arthritis. (22, 23, 24)
• Taurine and some other compounds protect cells from elevated retinol. Taurine binds with retinoic acid and helps the body clear it. Taurine appears to be (at least partially) the body's natural defence against the accumulation of retinol. A compromised pancreas could lead to a significant reduction in taurine levels.
• Zinc is required to make retinol binding proteins. (11, 14)
• Bitter leaves as a part of the daily diet. See Limiting digestion of plant retinoids.
• Nicotine patches. Living in Australia, I can buy 21 mg nicotine patches, sold to help smokers give up their habit. I cut each patch into four pieces and use one piece per day, taking breaks as detailed here. Note that tobacco is a bitter leaf.
• Coffee. It may be drunk or used as an enema.
• Nitric oxide. The best way to encourage production of NO in the body is through sun exposure. A healthy biome in the mouth and gut biome is also positive. Tongue scraping on getting up in the morning helps the mouth biome, but more important is avoiding (antiseptic) mouthwashes.
• Ultra violet light, sun exposure. UV can break down retinol molecules. (17) This must be balanced against increased skin sensitivity from retinols in the skin.
• ADH (alcohol dehydrogenase) is a zinc-containing cytosolic enzyme that oxidizes ethanol to acetaldehyde. Its most important function is the detoxification of ethanol, but it also breaks down retinoids, and specifically retinoic acid. (15) Genereux suggests using ADH combined with zinc. Several foods may assist with ADH production, including sweet lime and pear, particularly Asian pears. (19)
• Activated charcoal. Bile contains vitamin A, which is reabsorbed in the small intestine in a closed loop. If this is suspected, Genereux suggests half a teaspoon of activated charcoal in a glass of water and taken just before breakfast each day. This could break the loop and draw down from the liver. However, this charcoal impairs the digestion of other nutrients and should not be taken for more than a few days. Activated charcoal is inexpensive and available at most pharmacies.
• Natural emulsifiers. Vitamin A is a fat-soluble molecule that is absorbed by fats, both dietary fats and the body's storage fats. Butter has a long history as a disease treatment. Butter fats emulsify circulating retinoids, so that prevents them immediately causing inflammation and cellular damage. They also help move retinoids into the liver. Butter fats also help cells build up and maintain their crucial fatty membranes. On balance, butter may be helpful, better than using olive oil as a primary source of fat.
• Avoid prolonged stress. Stress causes the liver to release more glycogen, accompanied by a small amount of vitamin A. This is why prolonged stress often precedes diseases such as cancer. Moderate exercise helps the muscles consume that glycogen and along with it the extra vitamin A.
• Cacao, cocoa, black chocolate as pure as possible with no added sugar or dairy.
• Turmeric (curcumin).
• Pineapple (bromelain, a protein-digesting enzyme).
• Ozone therapy.
• Vitamin E sufficiency but absolutely not excess. Vitamin E is a fat-soluble vitamin that competes for fat storage with vitamin A.

Your comments about any of your experiences - positive or negative - with vitamin A are welcome at Grow Youthful. I am always curious about your use of and experience with natural remedies, and your feedback is very welcome.

References

1. Grant Genereux. Grant lived in Arctic Canada in the 80's and observed the Intuit people there. There were high rates of cancer, and obvious dental problems. He refutes the writings of Weston Price. He has written three books on vitamin A that are freely downloadable from his website ggenereux.blog.

2. livertox.nih.gov/VitaminARetinoids.htm

3. Google search on 18/07/2025.

4. Li-hong Cheng, Yuto Ito. Retinoic Acid: Structure, Mechanisms and Roles in Disease. Nova Biomedical 2012. ISBN 978162100597.

5. Penniston Kristina L, et al. The acute and chronic toxic effects of vitamin A. The American Journal of Clinical Nutrition, Volume 83, Issue 2, 191 - 201. Feb 2006.

6. Rollman O, Vahlquist A. Vitamin A in skin and serum--studies of acne vulgaris, atopic dermatitis, ichthyosis vulgaris and lichen planus. Br J Dermatol. 1985 Oct;113(4):405-13.

7. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012. ncbi.nlm.nih.gov/books/NBK547852/.

8. Elizabeth Montgomery, Lysandra Voltaggio. Biopsy Interpretation of the Gastrointestinal Tract Mucosa. 2nd edition, Volume 1.

9. FAO/WHO expert consultation on human vitamin and mineral requirements, Chapter 7.

10. Molly Fox, Leslie A. Knapp, Paul W. Andrews, Corey L. Fincher. Hygiene and the world distribution of Alzheimer's disease: Epidemiological evidence for a relationship between microbial environment and age-adjusted disease burden. Evolution, Medicine, and Public Health, Volume 2013, Issue 1, 2013, Pages 173-186.

11. Pasantes-Morales H, et al. Protective Effect of Taurine, Zinc and Tocopherol on Retinol-Induced Damage in Human Lymphoblastoid Cells. The Journal of Nutrition, Volume 114, Issue 12, 2256 - 2261.

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17. Wang Z, Boudjelal M, Kang S, Voorhees JJ, Fisher GJ. Ultraviolet irradiation of human skin causes functional vitamin A deficiency, preventable by all-trans retinoic acid pre-treatment. Nat Med. 1999 Apr;5(4):418-22. doi: 10.1038/7417.

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19. Shraddha Srinivasan, Kriti Kumari Dubey, Rekha S Singhal. Influence of food commodities on hangover based on alcohol dehydrogenase and aldehyde dehydrogenase activities. Current Research in Food Science, Volume 1, 2019, Pages 8-16. ISSN 2665-9271.

20. HE Sauberlich, RE Hodges, DL Wallace, H Kolder, JE Canham, J Hood, N Raica Jr, LK Lowry. Vitamin A Metabolism and Requirements in the Human Studied with the Use of Labeled Retinol. Vitamins & Hormones, Volume 32, 1975, Pages 251-275.

21. A-Carotene, B-Carotene, B-Cryptoxanthin, Lycopene, Lutein, and Zeaxanthin. Oregon State University, Linus Pauling Institute, Micronutrient Information Center. Online, 24 April 2025.

22. Zhang W, Zhang L, Huang Z, Cai S, Ye Z, Chen Z, Huang J, Liu Z. The Effects of Oral Sodium Bicarbonate on Renal Function and Cardiovascular Risk in Patients with Chronic Kidney Disease: A Systematic Review and Meta-Analysis. (2021). Therapeutics and Clinical Risk Management, 17, 1269-1282.

23. Robey IF, Baggett BK, Kirkpatrick ND, Roe DJ, Dosescu J, Sloane BF, Hashim AI, Morse DL, Raghunand N, Gatenby RA, Gillies RJ. Bicarbonate increases tumor pH and inhibits spontaneous metastases. Cancer Res. 2009 Mar 15;69(6):2260-8. doi: 10.1158/0008-5472.CAN-07-5575. Epub 2009 Mar 10. PMID: 19276390; PMCID: PMC2834485.

24. Sarah C. Ray, Babak Baban, Matthew A. Tucker, Alec J. Seaton, Kyu Chul Chang, Elinor C. Mannon, Jingping Sun, Bansari Patel, Katie Wilson, Jacqueline B. Musall, Hiram Ocasio, Debra Irsik, Jessica A. Filosa, Jennifer C. Sullivan, Brendan Marshall, Ryan A. Harris, Paul M. O'Connor. Oral NaHCO3 Activates a Splenic Anti-Inflammatory Pathway: Evidence That Cholinergic Signals Are Transmitted via Mesothelial Cells. The Journal of Immunology, 2018; ji1701605.

25. US National Academy of Medicine, on Wikipedia on 19 June 2025.