{"id":20982,"date":"2022-05-20T17:07:24","date_gmt":"2022-05-20T09:07:24","guid":{"rendered":"https:\/\/gogoherbs.com\/?p=20982"},"modified":"2026-09-24T20:21:09","modified_gmt":"2026-09-24T12:21:09","slug":"%e7%b6%ad%e4%bb%96%e5%91%bda%e5%8a%9f%e6%95%88%e3%80%81%e9%a3%9f%e7%89%a9%e4%be%86%e6%ba%90%e3%80%81%e4%bf%9d%e5%81%a5%e5%93%81%e6%8e%a8%e8%96%a6","status":"publish","type":"post","link":"https:\/\/gogoherbs.com\/en\/%e7%b6%ad%e4%bb%96%e5%91%bda%e5%8a%9f%e6%95%88%e3%80%81%e9%a3%9f%e7%89%a9%e4%be%86%e6%ba%90%e3%80%81%e4%bf%9d%e5%81%a5%e5%93%81%e6%8e%a8%e8%96%a6","title":{"rendered":"The benefits of Vitamin A, its food sources, and key points for choosing supplements."},"content":{"rendered":"
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Vitamin A is not a single substance, but a collective term for a group of related compounds, which can be divided into two main categories: those derived from animal foods.Pre-made Vitamin A<\/b>(Represented by retinol), and those derived from plants.Provitamin A carotenoids<\/b>(Primarily composed of beta-carotene, which must be converted into retinol in the body). It has...Low-light vision, immune defense, epithelium and mucous membranes, growth and development<\/b>All are important; the body also stores vitamin A (80%\u201390%) in the liver. However, precisely because it belongs to...Fat-soluble, it will accumulate in the body<\/b>It is also one of the few vitamins where "taking too much can be risky." This article summarizes the effects and positioning of vitamin A, daily requirements and safe upper limits, symptoms of deficiency and excess, food content, and how to choose health supplements.<\/p>\r\n<\/blockquote>\r\n

Medical Boundary Reminder:<\/strong>This article is a compilation of nutritional knowledge.This does not constitute medical diagnosis, treatment, prevention advice or prescription.<\/b>Vitamin A supplements are considered a daily nutritional aid.It cannot replace a balanced diet, eye exams, corrective lenses, or doctor's prescription treatments.<\/b>Pregnant women, those planning to become pregnant, breastfeeding mothers, children, the elderly, those with abnormal liver function, or those currently taking prescription medications (especially anticoagulants or oral retinoids) should consult a doctor or pharmacist before using any supplements.Do not take high doses of vitamin A for an extended period without medical advice.<\/b><\/div>\r\n
Table of contents<\/strong>\r\n
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  1. What is Vitamin A? Two Forms and Their Roles<\/a><\/li>\r\n
  2. The benefits of Vitamin A: A look at its evidence-based effects.<\/a><\/li>\r\n
  3. Who needs to pay special attention to their vitamin A intake?<\/a><\/li>\r\n
  4. How much is needed daily? What is the safe limit?<\/a><\/li>\r\n
  5. Vitamin A deficiency and excess: Pay attention to both.<\/a><\/li>\r\n
  6. Natural food sources of Vitamin A<\/a><\/li>\r\n
  7. How to choose vitamin A supplements?<\/a><\/li>\r\n
  8. When should you seek medical attention?<\/a><\/li>\r\n
  9. Frequently Asked Questions (FAQ)<\/a><\/li>\r\n
  10. Source of information<\/a><\/li>\r\n<\/ol>\r\n<\/div>\r\n

    1. What is Vitamin A? Its two forms and roles.<\/h2>\r\n

    \u4f9d\u00a0The Office of Dietary Supplements (NIH ODS) of the National Institutes of Health<\/a>Vitamin A exists in two forms in diet and supplements, with different properties and absorption rates:<\/p>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
    \u00a0<\/th>\r\nPreformed Vitamin A<\/th>\r\nProvitamin A (carotenoids)<\/th>\r\n<\/tr>\r\n
    Representative ingredients<\/b><\/td>\r\nRetinol, retinyl esters, retinaldehyde, retinoic acid<\/td>\r\n\u03b2-carotene, \u03b1-carotene, \u03b2-cryptoxanthin<\/td>\r\n<\/tr>\r\n
    source<\/b><\/td>\r\nOnly inanimal food<\/b>Liver, egg yolks, dairy products, oily fish, cod liver oil; supplements often use retinyl acetate or retinyl palmitate.<\/td>\r\nplant-based foods<\/b>Orange-yellow and dark green fruits and vegetables (carrots, sweet potatoes, pumpkins, spinach, mangoes, cantaloupes, etc.)<\/td>\r\n<\/tr>\r\n
    Absorption and Conversion<\/b><\/td>\r\nIt can be used directly.Absorption rate approximately 701 TP4T1 TP1T901 TP4T<\/b><\/td>\r\nIt needs to be converted into retinol in the body.Conversion efficiency varies from person to person<\/b>(Affected by genes, dietary fats, and intestinal condition); Absorption rate range: 8.71 TP4T1 TP1T651 TP4T<\/td>\r\n<\/tr>\r\n
    Excess risk<\/b><\/td>\r\nIt will accumulate in the liver.Excessive dosage carries the risk of poisoning.<\/b>It has a tolerance limit.<\/td>\r\nIt will not cause vitamin A poisoning; excessive intake will only cause yellowing of the skin (see Section 5).<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n

    To ensure a consistent comparison, dietary guidelines and labeling generally use...Retinol activity equivalents (RAE)<\/b>Calculations, in micrograms (mcg):<\/p>\r\n