Vitamin A Rich Diet
by Sue Kira, Naturopath & Clinical Nutritionist
Different types of vitamin A and their conversion
Ways to improve conversion and absorption of vitamin A
Good food sources of vitamin A
About Vitamin A
Vitamin A is important for our immune system, healthy vision, and healthy growth of our cells. Vitamin A needs to work synergistically with other vitamins and minerals to function properly, such as vitamin D, K2, zinc, and magnesium.
Vitamin A is a fat-soluble vitamin that is also a powerful antioxidant. Vitamin A plays a critical role in maintaining healthy skin, healthy vision, neurological function and much more. Vitamin A, like all antioxidants, is involved in reducing inflammation by fighting free radical damage.
Antioxidants like Vitamin A are also responsible for building strong bones, regulating genes and supporting immune function. Some of the best sources of Vitamin A include eggs, liver, carrots, yellow or orange vegetables such as squash/pumpkin, spinach and any leafy green vegetable.
Common uses for vitamin A as a supplement are eye conditions, especially night blindness, rough dry or prematurely aging skin, loss of sense of smell, loss of appetite, fatigue, skin blemishes, brittle fingernails, sties in eyes, and even for more severe symptoms such as corneal ulcers and soft bones and teeth.
One of the richest natural sources of pre-formed vitamin A is in the liver of cod fish, usually sold as a cod liver oil supplement, which is naturally high in vitamins A and D, but not so high in the healthy Omega 3’s called EPA and DHA.
Benefits of adequate levels of vitamin A
Healthy eyes
Beta carotene, the form of vitamin A found in plants, has been shown in studies to play a role in preventing macular degeneration, the leading cause of age-related blindness. But you probably need to cook the veggies with some oil to get absorption happening, or eat the vegies with eggs or liver, as vitamin A is fat soluble and vegetables are mostly water. Vitamin A is a critical part of a molecule called ‘rhodopsin’, which is activated when light shines on the retina and it sends a signal to the brain, which results in vision.
Healthy immune system
Many immune system functions rely on sufficient vitamin A, which is why it is known as an important immune boosting vitamin. Genes that are involved in immune responses need vitamin A to regulate them, which means it is essential for fighting serious conditions like cancer and autoimmune diseases, but also illnesses like the flu or common colds. Beta-carotene is also a powerful antioxidant that can support the immune system to prevent a variety of chronic illnesses. Vitamin A is especially good for the immune systems of children.
Anti-inflammatory
Vitamin A has antioxidant properties that can neutralize free radicals in the body that can cause tissue and cellular damage. When the immune system overreacts to food proteins, creating food allergies and inflammation, vitamin A helps to reduce the inflammatory reaction.
Healthy skin and healthy cells
Vitamin A is necessary for wound healing and skin re-growth by forming glycoproteins, a combination of a type of sugar and protein. This helps the cells to bind together to form soft tissues and heal all epithelial (skin) cells, both internally and externally, as well as being a powerful aid to fight skin cancer.
Vitamin A keeps the lines and wrinkles away by producing collagen, which is responsible for keeping the skin looking young and supple. Vitamin A also contributes to healthy glowing hair.
What can happen with vitamin A deficiency?
Poor eye health
Vitamin A deficiency can lead to a thickening and softening of the cornea. If the corneas continue to soften, this may lead to infected corneas, a rupture, or degenerative tissue changes which can all lead to blindness. Keratomalacia, a condition that comes from severe deficiency of vitamin A, is a condition which often starts with night blindness and extreme dryness of the eyes, leading to eventual blindness if not treated.
Immune impairment
Vitamin A deficiency can impair the immune system and increase the risk for respiratory infections as well as growth retardation for the young. In some poorer countries where they don’t get many vegetables or meat and live off foods like white yams, it is very common for the child mortality rate to exceed 50% from severe vitamin A deficiency.
We watched a documentary where they grew orange sweet potatoes in addition to yams and the results were amazing. Fewer children died, they had better eye sight, better eye health and overall better immunity, just from making this one change. I’m not sure if they had fats etc to help with the conversion but it was obviously enough to save these poor children from the devastating effects of vitamin A deficiency.
Premature skin damage
Vitamin A deficiency leads to the skin scaling and drying, as well as follicular thickening, which is called keratinisation. This happens when the epithelial (surface of skin cells) cells lose their moisture and become hard and dry. This can also happen in the mucous membranes of the respiratory, gastrointestinal, and urinary tract.
Pregnancy deficiency risk
It is common for pregnant women to be deficient in vitamin A, especially during the last trimester when the demand from the baby is the highest, which can lead to night blindness if the mother’s vitamin A intake needs are not met.
Vitamin A excess signs
High doses of vitamin A may do more harm than good, especially from supplements, and even more so in combination with other supplemental antioxidants.
Consuming too much Vitamin A from supplementation has been associated with birth defects, decreased bone density and liver problems. Over consumption of supplemental vitamin A can lead to jaundice, nausea, loss of appetite, irritability, vomiting and even hair loss.
If you are going to consume Vitamin A supplements, make sure you only take low doses and use supplements that are food-based sources. It’s also important to consult your health care practitioner for advice. People who drink heavily, smoke or have kidney or liver disease should not take vitamin A supplements before talking to a doctor.
Symptoms of vitamin A toxicity
- dry skin
- joint pain
- vomiting
- headaches
- confusion
Vitamin A supplements may interact with some contraceptive pills, acne medicines (like Accutane), blood thinners (like Coumadin), cancer treatments and many other drugs. If you take any medicines, ask your doctor if vitamin A supplements are safe for you.
While vitamin A toxicity can cause serious issues for your health, toxicity usually comes from the improper or excessive use of supplements containing retinoid (vitamin A) and not from our diet. Foods do not contain enough vitamin A to create a toxicity issue.
Different types of vitamin A and their conversion
There are different types of vitamin A which can be divided into two main categories:
R1. Retinoids (aka retinol). These are the more bio-available (absorbable) forms of vitamin A found in animal products like eggs, meat, especially liver, and fish.
C2. Carotenoids, also called pre-vitamin A. These are found in plant foods such as vegetables like carrots and sweet potato (the yellow/orange colour is the carotenoid) and many green vegetables.
The only type of vitamin A your body can easily absorb and use is retinol, found in animal foods.
When you get vitamin A from carotenoids in plant sources, your body must convert these carotenoids into a bio-available retinol. This can happen easily if you are in great health, but for many people this can be an issue.
Factors such as genetics, alcohol use, certain medicines, toxic exposures, diabetes, gallbladder disease, liver disease – and digestive problems such as Crohn’s disease, ulcerative colitis, celiac, insufficient bile, leaky gut syndrome and pancreatic enzyme deficiency, all reduce the capacity for the conversion. Even without the above conditions, most people have compromised ability to convert carotenes to retinols.
If you consume a low-fat diet, then your conversion rate of carotenes to retinols will be inadequate, because you need healthy fats for this conversion to take place. A moderate to high fat diet on the other hand improves absorption because bile, which is excreted in response to fats, is needed as part of the conversion process.
Apart from these dietary and health factors, other things that interfere with absorption include strenuous exercise within 4hrs of consuming carotenoid rich foods, and the consumption of alcohol. Iron supplements and the use of cortisone and many other drugs also negatively affect absorption. The consumption of polyunsaturated fats with carotene (e.g. margarine with carrots) results in destruction of carotene unless antioxidants are also present.
Once vitamin A is stored in places like the liver, zinc is used by the liver to obtain vitamin A from its storage deposits, so a zinc deficiency can also lead to a vitamin A deficiency.
While a bit technical, I do wish to share with you that within the two types of vitamin A, there are also several sub-groups or types that all play different roles in the body, yet share a common feature in that they are all types of anti-inflammatory antioxidants.
Retinoids
Found in animal foods, retinoids include retinol, retinal, retinoic acid and retinyl esters.
Retinoid forms of vitamin A are especially important for pregnancy, childbirth and through infancy. It is also necessary for childhood growth, night vision, resistance to infectious disease, and red blood cell production. Even if you are not faced with any of these conditions, each of these retinoid forms of vitamin A play a role in protecting your body.
Carotenoids
Found in plant foods, carotenoids are broken down into two sub-groups called Carotenes and Xanthophylls. Within the carotenes there are alpha-carotene*, beta-carotene* (in carrots), gamma-carotene*, delta-carotene, epsilon-carotene, and zeta-carotene. Xanthophylls include astaxanthin, beta-cryptoxanthin*, canthaxanthin, fucoxanthin, lutein, neoxanthin, violaxanthin and zeaxanthin.
Those with the asterisk* denote that once a food with this substance has been consumed, these carotenoid forms of vitamin A may be converted by the body into retinoid forms under certain conditions. The others do not form into retinoids but are types of anti-inflammatory antioxidants useful in many other ways (some similar in action to vitamin A) such as how astaxanthin, which is a type of vitamin A (the pink/orange antioxidant pigment found in salmon) is great for the eyes and cardiovascular system.
Most carotenoid forms of vitamin A function as anti-inflammatory and antioxidant nutrients. Sometimes certain carotenoids have a specific role to play in our health. For example, the carotenoids found inside the retina of the human eye are the xanthophylls, lutein and zeaxanthin.
Anyone needing to focus on vitamin A benefits related to eye health, such as prevention of macular degeneration, would need a meal plan that not only included foods that are rich in vitamin A, but rich in these two specific carotenoid forms of the vitamin, found in spinach, kale and Swiss chard.
A variety of different Vitamin A rich foods in your diet will ensure all bases are covered so you don’t have to think about which ones are needed.
Ways to improve conversion and absorption of vitamin A
Many people think that if they eat plenty of veggies such as carrots and sweet potato they are getting plenty of vitamin A. But if your body cannot convert the beta-carotene (from carrots) into retinol, then without animal products you are likely to end up with a deficiency. So the trick is to eat animal foods with your high carotene veggies.
However, if you are vegan or vegetarian then cooking, puréeing, or mashing vegetables ruptures the cell membranes and makes carotene more available for absorption, especially if you mix your mash with some oils such as coconut oil as this helps the release of bile to assist in the breakdown and absorption.
Most of us know that carotene (as Beta-carotene) is abundant in carrots, but you can find more in certain green leafy vegetables such as beetroot greens or spinach. As mentioned, the conversion of carotene is not 100% complete. Apparently less than ¼ from carrots and other root vegetables and ½ from green vegetables undergo this conversion.
Approximately 90% of vitamin A is stored in the liver with small amounts stored in the fat tissue, lungs, kidneys, and retina of the eyes. The un-stored carotene is excreted in the stools.
Recommended daily allowance (RDA) of Vitamin A
The following recommended daily allowance (RDA) for vitamin A includes the total from both food and supplements. The amounts are expressed in micrograms (mcg). A microgram = 1,000th of a milligram.
Children
- 1-3 years: need 300mcg
- 4-8 years: need 400mcg
- 9-13 years: need 600mcg
Adult Females
- 14 years+: need 700mcg
- Pregnant: need 750-770mcg
- Breastfeeding: need 1,200 to 1,300mcg
Adult Males
- 14 years+: need 900mcg
Good food sources of vitamin A
Following are foods rich in vitamin A, showing the weight of the food and the quantity of all forms of vitamin A in mcg. This list of foods can be used in conjunction with the above RDA’s. You can see that it is relatively easy to obtain sufficient levels of vitamin A from your diet.
- Beef Liver: 3oz/85g = 4,300mcg (any type of liver is high)
- Sweet potato: 1 cup = 1922mcg
- Carrots: 1 cup = 1,020mcg
- Spinach: 1 cup = 945mcg
- Kale: 1 cup = 885mcg
- Mustard greens: 1 cup = 865mcg
- Collard greens: 1 cup = 770mcg
- Romaine Lettuce (shredded): 1 cup = 409mcg
- Bok choy: 1 cup = 361mcg
- Broccoli: 1 cup = 121mcg
- Papaya: 1 cup = 130mcg
- Eggs (medium): 1 = 75mcg
Important:
Before you commence your diet, see your medical or health care professional for qualified guidance about what foods and supplements are best for your body. While on the diet do not stop any medications or supplements previously prescribed unless advised otherwise by your medical or health care professional.
During the early stages of a new diet, you may experience symptoms such as fatigue, headaches, or body aches, which may occur because your body is detoxifying. However, if you are unsure about a symptom at any time, check immediately with your medical or health care professional.