Vitamin A, also known as Retinol, is an essential nutrient, meaning that it is essential for health and life and must be obtained through diet. It's called Vitamin A because it was the first vitamin identified and was isolated from butter in 1913. Researchers went on to discover its importance for immunity, bone growth, mucous membranes and the eyes, skin, hair and nails.
Cod liver oil supplements became a regular part of children's upbringing in the early part of the twentieth century because they contain both Vitamin A and Vitamin D, essential for healthy growth and development. Adults benefit from fish liver oils as well and, although people these days often take Fish Oil, they are largely unaware of the different role of fish liver oil in good health.
What is the difference between Fish Oil & Fish Liver Oil?
Fish oil comes from the oils in the flesh of fish and contains mainly omega 3 fats with very little Retinol or Vitamin D; Fish Liver Oil comes from the liver of fish where Retinol and Vitamin D are stored and is therefore rich in these vitamins.
Where do we find Retinol?
Retinol is fat-soluble and is only found in animal foods that contain fat, liver being a particularly rich source. Some types of vegetables and fruit contain the orange pigment beta-carotene that can be converted to Retinol in your body but only a small amount of Retinol is made in this way.
If you take in more Retinol than you need for day-to-day uses, it is stored in your liver and fat tissue and mobilised as you need it. Zinc is essential for moving Retinol out of the liver. You need to eat some fat with Retinol and beta-carotene as they both need the presence of fat for effective absorption. If you are on a low-fat diet, you will miss out on Retinol from food and you may not absorb beta-carotene very well.
What does Retinol do?
Retinol can be converted to Retinoic Acid which interacts with genes to regulate cell growth and development. Retinol is particularly important for normal growth and for the health of your bones, eyes, mucous membranes and immune system. It is used more rapidly during infections and when you are exposed to bright light and glare.
What are the benefits of Retinol?
- Boosts Immunity:
Retinol boosts production of immune cells and helps activate the immune response. It stimulates antibody production and helps make the identifying proteins on your cell membranes that protect them from immune attack. Vitamin A requirements are increased during infections, especially measles, a severe deficiency is linked to the high rate of childhood deaths from measles in third world countries.
Retinol is needed for making visual purple, the eye pigment that allows us to see in dim light. It also keeps the outer lining tissues of the eyes healthy. If you are low in retinol you may develop sore, tired eyes that are sensitive to glare and have difficulty seeing well while driving at night.
- Maintains Healthy Cell Replication:
Retinoic acid formed from Retinol acts on genes to regulate cell replication. It helps cells develop properly into their mature, functional form.
- Maintains Healthy Hair, Skin, Nails and Mucous Membranes:
Retinol controls cell division in the skin and mucous membranes. A deficiency can cause cells to develop abnormally and leads to drying of mucous membranes, increased susceptibility to infections, weak nails, dry, flaky scalp, dry hair and dry, flaky, cracked, rough or 'gooseflesh' skin.
- Maintains Growth and Repair:
Retinol helps form connective tissue and is important in children and adults for healing and the healthy structure of bones, teeth and joints.
How much Retinol do you need each day?
The Australian government recommends that the average person in good health needs the following amounts: Recommended daily intake of retinol:
| Age group & gender | Micrograms (mcg) | International units (IU) |
| Men 19 + yrs | 900 | 3000 |
| Women 19 + yrs | 700 | 2333 |
| Pregnancy 14-18 yrs | 700 | 2333 |
| Pregnancy 19-50 yrs | 800 | 2667 |
| Lactation 14-50 yrs | 1100 | 3667 |
Can it be harmful?
You may be cautious about taking Retinol because you may be concerned about toxicity. There is no doubt that it can be toxic but the amount a non-pregnant adult would need to take to cause harm is very high, usually more than 25,000 IU (7,500 mcg) a day taken over a period of time. Toxicity effects are reversible once the excessive intake is stopped.
Beta-carotene has limited conversion to Retinol in the body and does not cause Retinol toxicity, however large amounts can build up in the skin and cause a harmless orange discolouration. Retinol is an essential nutrient and a deficiency also has adverse effects on your health. You need to make sure that you get the recommended amount each day.
Retinol Intake & Pregnancy:
Taking more than 8000 IU of retinol (2400 mcg) in pregnancy may cause birth defects. If you are pregnant or considering becoming pregnant, you should stick to the recommended dietary intake and check the total amount you are getting from supplements to ensure that you're not taking too much.
It's best to use a vitamin supplement designed specifically for pregnancy at this time as these usually include beta-carotene, not Retinol.
