Vitamin A Guide: Benefits, Food Sources & Recommended Dosage

Sep, 22 2025

Vitamin A is a fat‑soluble vitamin that supports vision, immune function, and skin health, measured in retinol activity equivalents (RAE). This guide breaks down why you need it, where to find it, and how much is safe.

Why Vitamin A Matters

When you hear "Vitamin A," most people think of carrots and night‑vision myths. The truth is broader: Vitamin A benefits span three core systems-eyes, immunity, and skin. In the retina, a form called Retinal acts as the light‑sensing molecule that converts photons into neural signals. Without enough retinal, night vision blurs and you’re more prone to eye infections.

Beyond sight, Vitamin A fuels the production of Retinoic acid a hormone‑like metabolite that regulates gene expression in immune cells. This keeps the frontline of your defense-white blood cells-ready to battle pathogens. Skin cells also rely on retinoic acid to differentiate and repair, which is why deficiency shows up as dry, flaky skin.

Forms of Vitamin A: Preformed vs Provitamin

Not all Vitamin A is created equal. There are two biologically active groups:

• Retinol the animal‑derived, preformed form found in liver, eggs, and dairy.
• Beta‑carotene a plant‑based provitamin that the body converts to retinol as needed.

Retinol is absorbed directly, making it highly bioavailable but also more likely to cause toxicity if over‑consumed. Beta‑carotene conversion is regulated; excess intake usually just turns the skin orange without harmful effects.

How Much Is Enough? Recommended Intake & RAE

National health agencies express Vitamin A needs in Retinol Activity Equivalents (RAE) a standardized unit that accounts for the different bioavailability of retinol and provitamin A. The Recommended Dietary Allowance (RDA) for adults is 900µg RAE for men and 700µg RAE for women. Pregnant or lactating women need a bit more, while children have age‑scaled targets.

Because Vitamin A is stored in the liver, short‑term fluctuations don’t matter as much as consistent long‑term intake. However, chronic oversupply-especially from high‑dose supplements-can lead to hypervitaminosis A, with symptoms ranging from headaches to liver damage.

Top Food Sources (What to Eat)

Here’s a quick cheat‑sheet of foods and their approximate RAE content per typical serving:

• Liver (beef, chicken): 6,500µg RAE per 100g (huge source-watch portion size)
• Cod liver oil: 4,500µg RAE per tablespoon
• Egg yolk: 70µg RAE per large egg
• Butter: 60µg RAE per tablespoon
• Carrots (raw): 835µg RAE per 100g
• Sweet potatoes (baked): 710µg RAE per medium tuber
• Spinach (cooked): 570µg RAE per cup
• Mango: 54µg RAE per cup

Notice the split: animal foods deliver preformed retinol, while colorful veggies give you beta‑carotene. Mixing both ensures you hit the RDA without risking toxicity.

Comparison: Preformed Retinol vs Provitamin Beta‑Carotene

The table shows why most nutritionists recommend getting the bulk of your Vitamin A from beta‑carotene‑rich plants and topping up with small amounts of animal sources.

Supplementing Vitamin A: When & How

Supplements are handy for groups at risk of deficiency-pregnant women, people with malabsorption disorders, and vegans who struggle to meet RAE goals. Choose a product that lists the amount in µg RAE, not IU (International Units), to avoid dosing errors.

A typical prenatal vitamin provides about 800µg RAE, which aligns with the woman’s RDA. If you’re already eating liver once a week, you probably don’t need extra. Always check the label for retinol vs beta‑carotene content; most multivitamins use preformed retinol.

Safety Tips & Common Pitfalls

• Don’t double‑dose. If you take a supplement and also eat liver regularly, you can cross the safe upper limit (3,000µg RAE for adults).
• Store supplements away from heat and light-retinol degrades into less active compounds.
• Beware of fortified foods that add Vitamin A; total intake can creep up without you realizing.
• People on cholesterol‑lowering drugs (e.g., bile‑acid sequestrants) may need higher Vitamin A because absorption drops.

Related Nutrients: The Bigger Picture

Vitamin A doesn’t work in isolation. It partners with other fat‑soluble vitamins-Vitamin D for calcium metabolism and Vitamin K for blood clotting-to keep cells healthy. Moreover, antioxidants like Zinc support the conversion of beta‑carotene to retinol enhance the efficiency of Vitamin A utilization.

Next‑level readers might explore how retinoic acid influences gene expression in skin aging, or how Vitamin A interacts with the gut microbiome to modulate immunity.

Quick Reference Checklist

• Know your RDA: 900µgRAE (men), 700µgRAE (women).
• Aim for 2-3 servings of beta‑carotene‑rich veggies daily.
• Limit liver to once a week if you also take a supplement.
• Choose supplements that list µgRAE, not IU.
• Watch for signs of excess: headache, nausea, skin yellow‑orange.