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Vitamin A is an essential nutrient that supports immunity, vision, cellular communication, and more. There are two forms of vitamin A, and they are distinctly different.
What is Vitamin A?
Most people think of vitamin A as one vitamin, but there are several forms of this fat-soluble nutrient. These include:
- Preformed vitamin A in the form of retinol and retinoic acid
- Provitamin A carotenoids in the form of beta-carotene, alpha-carotene, gamma-carotene, and beta-cryptoxanthin
The simplest way to distinguish between the two forms is that preformed vitamin A is found in animal products and provitamin A compounds are found in plant-based foods.
Preformed vitamin A is found in foods like liver, eggs, whole milk, butter, meat, and oily fish. Ancestral diets are typically quite rich in dietary vitamin A because of the focus on these whole foods. This form is most readily used by the body.
Provitamin A is found in vegetables that are commonly associated with vitamin A, like carrots, squash, and sweet potatoes. Beta-carotene is also found in leafy green vegetables, some fruits, and tree nuts. Even though it is called vitamin A, beta-carotene is primarily an antioxidant, though it also has other functions. It can be converted to vitamin A in the body, but the process is not efficient.
As beta-carotene in the diet increases, conversion to vitamin A decreases. So beta-carotene is not the optimal or efficient way to ensure that vitamin A levels are sufficient, and eating higher amounts of these beta-carotene foods will actually decrease the amount that becomes vitamin A. To support optimal bioavailability and conversion of beta-carotene into vitamin A, even at smaller amounts, it is best consumed with dietary fat.
Fat-soluble vitamins are stored by the body for later use. When consumed at levels that are too high, the body can become toxic from them. Most of the vitamin A that you consume is stored in the liver.
Health Benefits of Vitamin A
- Supports healthy immune function
- Promotes healthy vision and retinal receptors (which is why it helps improve night blindness)
- Promotes reproductive health
- Supports cellular communication, growth, and differentiation
- Maintains health of heart, lungs, kidneys, and other organs
Since beta-carotene is a separate nutrient that primarily functions as an antioxidant, its health benefits are separate from preformed vitamin A. They include:
- Neutralizes free radicals and reduces oxidative stress
- Supports healthy cognitive function
- Provides the body with small amounts of vitamin A
Food Sources of Vitamin A
Since vitamin A comes in two distinctly different forms, you’re really consuming two separate nutrients.
Foods that are rich in preformed vitamin A include:
- Fatty fish
- Whole milk
Foods that are rich in provitamin A like beta-carotene include:
- Leafy green vegetables
- Sweet potatoes
Both nutrients are needed to be healthy. If you only consume beta-carotene, you are not consuming enough dietary vitamin A.
Vitamin A Supplements
Vitamin A supplements come in many different formulations. Some include both preformed and provitamin A, while others rely primarily on one form or the other. Cod liver oil is a supplement that is high in preformed vitamin A.
True vitamin A deficiency in the US and developed countries is rare, although it may still be common to have suboptimal levels. Vitamin A is always essential, but it becomes even more important in pregnancy, lactation, infancy, and childhood, as well as certain medical conditions like cystic fibrosis.
Getting too much preformed vitamin A can be dangerous. During pregnancy, it can result in birth defects. In non-pregnant individuals, it can lead to hypervitaminosis A. Symptoms of excess vitamin A can include headaches, dizziness, nausea, skin irritation, joint pain, and liver damage. It can also lead to reduced bone mineral density and a higher risk for fractures. In extreme cases, it can result in coma or death.
Avoiding toxicity from fat-soluble vitamins is important because it can take anywhere from weeks to months to reverse the tissue build-up and, in some cases, the resulting liver damage may be irreversible. Vitamin A toxicity symptoms may also take months or years to show up after the point of saturation, so it’s important not to use symptoms to gauge appropriate intake amounts.
Beta-carotene is not toxic at any level, although high doses can lead to carotenoderma, a condition where the skin takes on an orange-yellow color. Reducing the intake of beta-carotene will resolve this condition.
(PPNF Note: When available, nutrition counseling is the best way to determine the supplements that are right for you. We understand that it is not always affordable or accessible. When taking supplements, follow recommended product guidelines unless a practitioner directs you otherwise.)
Today’s Simple Step
If you’re not used to eating foods that are rich in vitamin A, you’re in for a treat. They’re some of the most nutrient-dense foods and are also filled with flavor. Don’t fear dietary saturated fat and be generous in your diet with whole milk, grass-fed butter, eggs, and fatty fish, and eat organ meats, like liver, in moderation.