Vitamin A has two scientific names which are carotenoids and retinoids. Since it is one of the fat soluble vitamins, it requires the presence of fat upon ingestion for best absorption. When you have a meal with foods rich in vitamin A, you should incorporate some form of lipids such as a small amount of cooking oil (5 mL or 1 U.S teaspoon), butter, other sources rich in lipids (one third of an avocado, 50 mL of whole milk, 10-12 almonds, 5 macademia nuts, 12 peanuts or walnuts, 10 g of seeds).
Now, let’s talk more about the 2 forms of vitamin A. First, we have retinoids that come from animal sources (egg yolk, shrimp, tuna, salmon, sardine, cheese, cow’s milk, yogurt etc.) The Retinoids is the reason vitamin A can give us health benefits including anti inflammatory properties, red blood cell formation, immunity, bone growth, and night vision.
The second form of vitamin A, carotenoids, come from plant based foods. Carotenoids are the substances that give us the color of the retina. Also, Carotenoids act as antioxidants.
The difference between the two form is more significant when we talk about how our body handles them. Retinoids can be readily used by the body, but carotenoids can also be converted into retinoids under certain conditions. So, I feel it’s important to stress that we can get health benefits of retinoids without feeling stuck to animal food sources if some of us happen to be die-hard vegans. Our body is capable of converting carotenoids into retinoids so that we can get health benefits of both carotenoids and also health benefits of retinoids.
As I said above, the conversion happens with conditions. People with the following conditions may not have the capacity to convert carotenoids to retinoids:
- Digestion problems (low level of certain enzymes, issue with bile duct or bile production, etc.)
- Genetics disease (family history)
- Imbalance in bacterial activities in the digestive tract
- Excessive alcohol consumption (alcoholics)
- Overdose of vitamin A and vitamin D
- Long term exposure to toxic chemicals
- Negative reaction between food-drug interaction.
1/ Functions of vitamin A
- Participate in the growth of teeth, bones, skin, soft tissues, and mucous membranes. Therefore, children may suffer stunted growth if they have vitamin A deficiency in long term.
- Provide colors to the corneas
- Play critical role in vision, especially night vision
- Help protect against damages by free radicals
2/ Recommended Daily Intake (RDI): measured in micro-gram
- 0-6 month old: 400 mcg/day
- 7-12 month old: 500 mcg/day
- 1-3 years old: 300 mcg/day
- 4-8 years old: 400 mcg/day
- 9-13 years old: 600 mcg/day
- Male from 14 years: 900 mcg/day
- Female from 14 years: 700 mcg/day
- Pregnant women: 770 mcg/day
- Lactating women: 1300 mcg/day
3/ Vitamin A deficiency: Signs and Symptoms:
- Night blindness
- Dry/itchy/tiring eyes
- Skin issues: dry skin, acnes, scaling
- Dry hair
- Weak gums and teeth
- Susceptible to cold, coughing (weak immune system)
- Stunted growth in chidlren
- Permanent blindness if left unchecked.
4/ Antioxidant property of carotenoids:
When you consume foods done at high temperature (deep fried, broiled, grilled, baked at high temperature) tend to leave behind free radicals when the foods are processed. These free radicals function very much as carcinogens, which cause damage to healthy cells. When you finish with your workout, your muscles are actually similar to a battle field with a lot of damages left behind. Through exercise, free radicals are brought upon. Free radicals and their chain reaction are the pathway to cellular damages which are the pathway to cancer, aging, and many diseases. Antioxidants are part of the body self defense system that interact with the chain reactions initiated by free radicals.
So, vitamin A is not an antioxidant, but the carotenoids which is one of the 2 forms of vitamin A in foods, act as antioxidant. Since carotenoids are abundant in plants (spinach, kale, carrot, sweet potato, etc…), it may be better to obtain both nutritional value of vitamin A and antioxidant while not wrecking your calories with vitamin A (retinoids) coming from animal sources. It’s no brainer that animal sources always have more calories and possibly less nutrient dense per weight compared to plant sources.
Carotenoids have many forms, too. However, beta-carotene seems to have highest antioxidant activities and also easier to be converted to retinoids. Carrot is probably the most popular source of beta-carotene. After all, carrots and beta-CAROTene have something in common, don’t they?
5/ Good food sources:
All fruits have certain amount of vitamin A in the form of carotenoids. Many vegetables also are rich sources of vitamin A, such as sweet potatoes, pumpkins, bok toy, spinach, beet greens, and of course carrots. Usually, if you consume a portion of 150 g of these vegetables and have no health issue preventing carotenoids to retinoids, you should be able to get all health benefits of vitamin A.
|Baked sweet potatoes, with skin on,||200g||1096 mcg|
|Cooked pumpkin||125 g||1007 mcg|
|Carrot juice||125mL||966 mcg|
|Cooked carrots||60 g||653 mcg|
|Raw carrots||120 g||1000 mcg|
|Beet greens, steamed||60 g||566 mcg|
|Cooked bok choy||30 g||190 mcg|
|Cooked turnip greens or collard greens||60 g||406-516 mcg|
|Romaine Lettuce||60 g||258 mcg|
|Red bell pepper||60 g||468-505 mcg|
|Cooked spinach||125 g||498 mcg|
|Note: It’s better to eat a variety of vegetables to get the most nutrients|
Vitamin A in the form of retinoids is abundant in certain animal sources. The best source is liver, followed by shrimp and egg yolk. However, I personally will not rely on liver, shrimp and egg yolk as my main source of vitamin A, primarily because they contain lots of cholesterol. Animal organs seem to find their way to many Asian cuisine, including Vietnamese cuisine. I admit I love organ meat, but I’ll just look at them as treats. I can’t recall when the last time I ate organ meat.
|Cooked pork liver||75 g||4054 mcg|
|Cooked chicken liver||75 g||3222 mcg|