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Vitamin A

Specific Recommendations:

• carotenoids - (beta carotene, a carotenoid, is converted to vitamin A as needed.  However, taking just one of over 600 carotenoids can cause a deficiency of the others)
• Vitamin A products at Amazon.com

News & Research:

• Higher vitamin A intake linked to lower skin cancer risk - Science Daily, 7/31/19 - "People whose diets included high levels of vitamin A had a 17 percent reduction in risk for getting the second-most-common type of skin cancer, as compared to those who ate modest amounts of foods and supplements rich in vitamin A"
• Vitamins A and C help erase cell memory - Science Daily, 10/12/16 - "For regenerative medicine, the holy grail is to be able to generate a cell that can be directed to become any other cell, such as brain cells, heart cells and lung cells ... We found out that the mechanisms of how vitamins A and C enhance demethylation are different, yet synergistic"
• Vitamin A implicated in development of alcoholic liver disease - Science Daily, 9/1/15 - "Long-term drinking lowers vitamin A levels in the liver, which is the main site of alcohol breakdown and vitamin A storage, while raising vitamin A levels in many other tissues"
• Vitamin A is for anti-aging, at least when it comes to vision - The Washington Post, 7/14/15 - "There are essentially two forms of the vitamin: retinoids, or preformed vitamin A, found in animal products and carotenoids; and provitamin A, dark-colored plant pigments that are converted to vitamin A in the body ... Food sources: Liver, shrimp, salmon, sardines, halibut, cod, beef, lamb, eggs, whole milk, whole yogurt ... Carotenoids are antioxidants that prevent and repair cellular damage and aging and reduce inflammation in the eyes and elsewhere in the body. The carotenoids lutein and zeaxanthin are found in the retina of the human eye and have been shown to help prevent age-related macular degeneration. Carotenoids also may reduce the risk for cancer ... Food sources: Spinach, kale, Swiss chard, other dark leafy greens, carrots, sweet potatoes, winter squash, apricots and cantaloupe ... Not only does vitamin A help with eyesight by producing the pigments of the retina and preventing macular degeneration, but it also helps create and maintain healthy skin (hence the popularity of topical Retin-A skincare products) ... Avoid excessively bright light from harsh interior lighting or strong sunlight. Most offices are twice as bright as they need to be. Use low-intensity light bulbs and floor lamps instead of fluorescent lighting" - See Puritan's Pride Lutein 20 mg with Zeaxanthin-120 Softgels at Amazon.com.
• Can vitamin A turn back the clock on breast cancer? - Science Daily, 3/31/14 - "A derivative of vitamin A, known as retinoic acid, found abundantly in sweet potato and carrots, helps turn pre-cancer cells back to normal healthy breast cells ... used a model of breast cancer progression composed of four types of cells each one representing a different stage of breast cancer: normal, pre-cancerous, cancerous and a fully aggressive model ... When the researchers exposed the four breast cell types to different concentrations of retinoic acid – one of the chemicals that the body converts vitamin A into – they noticed a strong change in the pre-cancerous cells. Not only did the pre-cancerous cells begin to look more like normal cells in terms of their shape, they also changed their genetic signature back to normal"
• Listen up! Antioxidants may slash risk of hearing loss, says study - Nutra USA, 7/19/11 - "People with the highest average intakes of vitamin A had a 47 percent reduced risk of moderate or greater hearing loss, compared to people with the lowest average intakes ... In addition, increasing dietary vitamin E intakes were linked with a 14 percent reduction in hearing loss"
• Vitamin A plays key role in the human body, study suggests - Science Daily, 3/17/11 - "Our study found that Vitamin A itself is active for activating nuclear receptor TR4 ... Because TR4 plays roles in sperm cell production, lipid and lipoprotein regulation, the development of the central nervous system, and the regulation of hemoglobin production in the embryo, we can imagine that Vitamin A may play more important roles in human physiology than was previously believed"
• Researchers discover additional benefit of vitamin A - Science Daily, 5/12/10 - "Children of mothers who received vitamin A supplementation before, during and after pregnancy had significantly improved lung function when compared to those whose mothers received beta-carotene supplementation or placebo"
• Vitamin A: Key mechanism that guides cells to form heart tissue - Science Daily, 3/19/10 - "Second Heart Field (SHF) ... retinoic acid (RA), a derivative of vitamin A, regulates the SHF tissue formation and the septation, or division, of the outflow tract into the ascending aorta and the pulmonary artery ... We now know that vitamin A is a critical regulator of this process, and too much or too little RA can lead to common congenital defects"
• Antioxidant compound reduced incidence of colorectal metachronous adenomas - Science Daily, 12/7/09 - "The researchers randomized 411 participants to the placebo group or to receive an antioxidant compound -- specifically selenomethionnine 200 μg, zinc 30 mg, vitamin A 6,000 IU, vitamin C 180 mg and vitamin E 30 mg ... individuals who consumed antioxidants had a 40 percent reduction in the incidence of metachronous adenomas of the large bowel ... It is noteworthy that the benefit observed after the conclusion of the trial persisted through 13 years of follow up"
• Too Much Of A Good Thing? Scientists Explain Cellular Effects Of Vitamin A Overdose And Deficiency - Science Daily, 10/8/09 - "retinol, the key component of vitamin A, is essential for the metabolic fitness of mitochondria and acts as a nutritional sensor for the creation of energy in cells. When there is too much or too little vitamin A, mitochondria do not function properly, wreaking havoc on our organs ... It goes to the nucleus of our cells and can affect our health for better or worse"
• Oxidized Form Of A Common Vitamin May Bring Relief For Ulcerative Colitis - Science Daily, 10/1/09 - "Here's another reason why you should take your vitamins. A new research report appearing in the October 2009 print issue of the Journal of Leukocyte Biology suggests that retinoic acid, the oxidized form of vitamin A, could be a beneficial treatment for people suffering from ulcerative colitis and other irritable bowel diseases"
• Don't Forget The Vitamin A When Working With Its Carrier Protein - Science Daily, 9/26/08
• How Embryos Regulate Vitamin A Derivatives: Too Much Or Too Little Linked To Birth Defects - Science Daily, 11/19/07
• Drug Slows Prostate Tumor Growth By Keeping Vitamin A Active - Science Daily, 11/7/07 - "A novel compound that blocks the breakdown of retinoic acid, derived from vitamin A, is a surprisingly effective and "promiscuous" agent in treating animal models of human prostate cancer ... Daily injections of the agent VN/14-1 resulted in up to a 50 percent decrease in tumor volume in mice implanted with human prostate cancer cells ... Vitamin A, when converted by the body into retinoic acid, is known to be involved in maintaining the normal growth of cells, and other research has shown that prostate cancer cells contain five to eight times less retinoic acid than normal prostate cells"
• Vitamin A Levels Affect Hip Fracture Risk - Physician's Weekly, 10/4/04 - "women with the lowest concentrations of vitamin A had a 90% higher risk of hip fracture. Those with the highest concentrations were twice as likely as those with normal levels to sustain a hip fracture"
• Too Much or Too Little Vitamin A Raises Hip-Fracture Risk in Post-Menopausal Women - Doctor's Guide, 6/24/03 - "the highest and lowest quintiles were at twice the risk of hip fracture compared to the middle quintile ... without knowing the vitamin A status of an individual, eliminating vitamin A supplements could actually increase the number of vitamin A-deficient individuals, which would put them at risk not only of hip fractures, but also for other health risks associated with low vitamin A"
• Vitamin A Safety - Dr. Janson's Newsletter, 2/03 - "what they did not mention was that those in the next to highest and middle ranges had a significantly lower risk than those with lower blood levels. The amounts in normal vitamin supplements appear to be quite safe  ... One problem with the latest study is that they measured blood levels just once at the beginning of the study 30 years ago. They assessed dietary intake with a questionnaire in only half of the subjects, when they were 20 years into the study. While this study gives cause for some concern, other studies are contradictory, so we have to be careful before drawing firm conclusions"
• Vitamin A, Steroids Could Help Keep Body Clocks in Sync - WebMD, 6/28/01 - "I think it will turn out that vitamin A will be a novel signaling mechanism, and that it will play a role maybe in [controlling] peripheral clocks [throughout the body]," says lead author Peter McNamara, PhD."
• Canceling Cancer: New Cancer Prevention Strategies on the Horizon - WebMD, 3/26/01 - "an enzyme called telomerase is important for the growth of most cancer cells but not so crucial for the growth of normal cells ... By giving a compound similar to vitamin A to a group of heavy smokers, they were able to reduce the amount of telomerase activity. Their findings indicate that this compound might be useful in the future to prevent lung cancer in former smokers"

Abstracts:

• Micronutrients and the risk of hip fracture: Case-control study - Clin Nutr. 2015 Dec 23 - "Vitamin D, and possibly vitamin K, has an established association to fracture risk. Other vitamins are, however, less studied ... Low vitamin A, C, and E concentrations are associated with an increased risk of hip fracture, possibly mediated through bone turnover mechanisms"
• Association of Dietary Vitamin A and β-Carotene Intake with the Risk of Lung Cancer: A Meta-Analysis of 19 Publications - Nutrients. 2015 Nov 11 - "he pooled RR and their 95% CI was 0.855 (0.739-0.989) for higher category of dietary vitamin A intake and lung cancer risk, especially among Asian populations and in the cohort studies. Evidence from 18 studies suggested that higher category of dietary β-carotene intake could reduce lung cancer risk (0.768" - See carotenoids at Amazon.com.
• Estimated intake of vitamin D and its interaction with vitamin A on lung cancer risk among smokers - Int J Cancer. 2014 Mar 13 - "Our observation suggests that vitamin A may assist vitamin D in preventing lung cancer among smokers"
• Association of blood antioxidants and vitamins with risk of age-related cataract: a meta-analysis of observational studies - Am J Clin Nutr. 2013 Jul 10 - "searched PubMed, EMBASE, and the Web of Science for relevant studies ... A pooled estimate showed vitamin E (OR: 0.75; 95% CI: 0.58, 0.96), α-carotene (OR: 0.72; 95% CI: 0.59, 0.88), lutein (OR: 0.75; 95% CI: 0.65, 0.87), and zeaxanthin (OR: 0.70; 95% CI: 0.60, 0.82) were inversely associated with age-related cataract. Vitamins A (OR: 0.69; 95% CI: 0.58, 0.83) and C (OR: 0.67; 95% CI: 0.57, 0.78) were inversely associated with age-related cataract in Asian populations but not in Western populations. β-Carotene (OR: 0.90; 95% CI: 0.78, 1.05), lycopene (OR: 0.86; 95% CI: 0.65, 1.15), and β-cryptoxanthin (OR: 0.83; 95% CI: 0.68, 1.02) had no significant association with risk of cataract" - See Jarrow Formulas, CarotenALL at Amazon.com and Jarrow FamilE (contains all eight members of the vitamin E family, includes Tocomin) at Amazon.com.
• The effect of vitamin a supplementation on thyroid function in premenopausal women - J Am Coll Nutr. 2012 Aug;31(4):268-74 - "Serum TSH concentrations in vitamin A-treated subjects were significantly reduced; therefore, vitamin A supplementation might reduce the risk of subclinical hypothyroidism in premenopausal women"
• Plasma retinol: A novel marker for cardiovascular disease mortality in Australian adults - Nutr Metab Cardiovasc Dis. 2011 Nov 25 - "Vitamin A affects inflammation and immune function and is thus a factor of interest in relation to cardiovascular disease (CVD). As vitamin A circulates in the plasma in the form of retinol, this study aims to describe the relationship between plasma retinol and the 5-year incidence of CVD mortality ... Community-dwelling adults (n = 441, 45% with type 2 diabetes) were recruited in Melbourne, assessed at baseline and followed for 5 years. At baseline, CVD risk factors were assessed by clinical evaluation, by personal lifestyle questionnaire and from biochemistry (plasma fasting glucose, lipids, total homocysteine, C-reactive protein, retinol and carotenoids plus the urinary albumin excretion rate over 24 h.). Dietary intake was assessed by a validated food frequency questionnaire. CVD mortality over 5-years was determined by consulting state or national registries. The majority of participants had adequate plasma retinol concentrations (≥30 μg/dL). The final Cox regression model indicated that those in the highest tertile of plasma retinol (mean +/- SD) 76 +/- 14 μg/dL) had a significantly lower risk of 5-year CVD mortality (hazard ratio 0.27 [95% confidence interval 0.11, 0.68], P = 0.005), an effect that was not readily explained in terms of traditional CVD risk factors or dietary intake"
• Associations of serum vitamin A and carotenoid levels with markers of prostate cancer detection among US men - Cancer Causes Control. 2011 Jul 29 - "Associations of serum vitamin A and carotenoid levels with markers of prostate cancer detection were evaluated among 3,927 US men, 40-85 years of age, who participated in the 2001-2006 National Health and Nutrition Examination Surveys. Five recommended definitions of prostate cancer detection were adopted using total and free prostate-specific antigen (tPSA and fPSA) laboratory measurements. Men were identified as high risk based on alternative cutoffs, namely tPSA > 10 ng/ml, tPSA > 4 ng/ml, tPSA > 2.5 ng/ml, %fPSA < 25%, and %fPSA < 15%. %fPSA was defined as (fPSA÷tPSA)× 100%. Serum levels of vitamin A (retinol and retinyl esters) and carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lutein + zeaxanthin, lycopene) were defined as quartiles and examined as risk/protective factors for PSA biomarkers. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using binary logistic models. After adjustment for known demographic, socioeconomic, and lifestyle confounders, high serum levels of retinyl esters (tPSA > 10 ng/ml: Q4 vs. Q1 → OR = 0.38, 95% CI: 0.14-1.00) and α-carotene (%fPSA < 15%: Q4 vs. Q1 → OR = 0.49, 95% CI: 0.32-0.76) were associated with a lower odds, whereas high serum level of lycopene (tPSA > 2.5 ng/ml: Q4 vs. Q1 → OR = 1.49, 95% CI: 1.01-2.14) was associated with a greater odds of prostate cancer detection. Apart from the three significant associations observed, no other exposure-outcome association was significant. Monitoring specific antioxidant levels may be helpful in the early detection of prostate cancer"
• Retinol, vitamins A, C, and E and breast cancer risk: a meta-analysis and meta-regression - Cancer Causes Control. 2011 Jul 15 - "Overall, 51 studies met the inclusion criteria. Comparing the highest with the lowest intake, total vitamin A intake reduced the breast cancer risk by 17% (pooled OR = 0.83, 95% CI: 0.78-0.88). Further subgroup analysis based on study design did not change the significant reduction. Although the dietary vitamin A, dietary vitamin E, and total vitamin E intake all reduced breast cancer risk significantly when data from all studies were pooled, the results became nonsignificant when data from cohort studies were pooled. The significant association between total retinol intake and breast cancer in all studies became nonsignificant in case-control studies but remain significant in cohort studies. No significant dose-response relationship was observed in the higher intake of these vitamins with reduced breast cancer risk"
• Vitamin A Decreases Pre-receptor Amplification of Glucocorticoids in Obesity: Study on the Effect of Vitamin A on 11beta-Hydroxysteroid Dehydrogenase Type 1 Activity in Liver and Visceral Fat of WNIN/Ob Obese Rats - Nutr J. 2011 Jun 23;10(1):70 - "11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) catalyzes the conversion of inactive glucocorticoids to active glucocorticoids and its inhibition ameliorates obesity and metabolic syndrome. So far, no studies have reported the effect of dietary vitamin A on 11beta-HSD1 activity in visceral fat and liver under normal and obese conditions. Here, we studied the effect of chronic feeding of vitamin A-enriched diet (129mg/kg diet) on 11beta-HSD1 activity in liver and visceral fat of WNIN/Ob lean and obese rats ... Control groups received stock diet containing 2.6mg vitamin A/kg diet, where as experimental groups received diet containing 129mg vitamin A/Kg diet for 20 weeks ... Vitamin A supplementation significantly decreased body weight, visceral fat mass and 11beta-HSD1 activity in visceral fat of WNIN/Ob obese rats. Hepatic 11beta-HSD1 activity and gene expression were significantly reduced by vitamin A supplementation in both the phenotypes. CCAAT/enhancer binding protein alpha(C/EBPalpha), the main transcription factor essential for the expression of 11beta-HSD1, decreased in liver by vitamin A fed-obese rats, but not in lean rats. Liver X receptor alpha (LXR alpha), a nuclear transcription factor which is known to downregulate 11beta-HSD1 gene expression was significantly increased by vitamin A supplementation in both the phenotypes" - Note:  See my 11beta-HSD1 page.  11beta-HSD1 goes hand in hand with cortisol.
• Serum Retinol and Prostate Cancer Risk: a Nested Case-Control Study in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial - Cancer Epidemiol Biomarkers Prev. 2009 Mar 31 - "Vitamin A (retinol) plays a key role in the regulation of cell growth and differentiation, and has been studied as a potential chemopreventive agent for prostate cancer ... the highest versus lowest concentrations of serum retinol were associated with a 42% reduction in aggressive prostate cancer risk (Ptrend = 0.02), with the strongest inverse association for high-grade disease (Gleason sum >7; odds ratio, 0.52; 95% confidence interval, 0.32-0.84; Ptrend = 0.01)"