Vitamin A is a group of compounds found as either active retinoids or inactive carotenoids1. Inactive carotenoids can be converted to the active retinoid form in the body. It is thought that people need both the retinoid form and carotenoid form in the diet, as the conversion rate of carotenoids to active forms of vitamin A isn’t as efficient in some people2. Retinoids are only found in animal products, and carotenoids are high in mainly red and orange fruits and vegetables, therefore, it could be suggested that those on a plant-based diet could benefit from a retinol supplement. However, taking too much vitamin A can cause more harm than good. Vitamin A is fat soluble, and not water soluble, so it’s much harder for your body to get rid of excess compared to water soluble vitamins, such as vitamin C.
Which foods are high in vitamin A?
Animal liver contains a lot of retinoids. One slice of beef liver contains over 700% of your daily suggested intake. But we know liver isn't common in most peoples' diets.
Half a fillet of mackerel - 43% of your daily intake
Half a fillet of salmon - 25% of your daily intake
Goat's cheese - 13% of your daily intake per serving
Butter - 11% of your daily intake per serving
Cheddar cheese - 10% of your daily intake per serving
One large boiled egg - 8% of your daily intake.
Depending on your genetics, you may convert a lot less of the carotenoids in the following foods to the active form of vitamin A, meaning you obtain much less vitamin A from the following foods than it states. Studies suggest up to 45% of people have low conversion rates of the most common carotenoid, beta-carotene, to the active form3.
1 cup of cooked sweet potato - 204% of your daily intake
1 cup of cooked kale - 98% of your daily intake
1 medium cooked carrot - 44% of your daily intake
1 large yellow bell pepper - 28% of your daily intake
1 cup of raw spinach - 16% of your daily intake.
Why do you need it?
Vitamin A deficiency has very serious health implications but is very rare in the developed world. The most common reason for vitamin A supplementation in the developed world is to treat acne. But how effective is vitamin A in acne treatment? Vitamin A has been shown to reduce inflammation and is a powerful antioxidant, both of which could contribute to healthier skin4. However, there is little evidence that shows vitamin A reduces the number of acne lesions, but reduced inflammation will help with the appearance5.
- Oregon State University Micronutrient Information Center, 2015
- Variability of the conversion of β-carotene to vitamin A in women measured by using a double-tracer study design. (Lin, 2000)
- Single nucleotide polymorphisms upstream from the β-carotene 15,15'-monoxygenase gene influence provitamin A conversion efficiency in female volunteers. (Lietz, 2012)
- Vitamin A as an anti-inflammatory agent. (Reifen, 2002)
- Effects of Oral Zinc and Vitamin A in Acne. (Michaëlsson, 1977)