Vitamin A And Vitamin D Explained: Forms, Foods And Labels

Two oil-soluble vitamins

Vitamins A and D belong to the group of oil-soluble vitamins, along with E and K. Oil-soluble means they dissolve in oils rather than in water, and so they are found in the oily parts of foods. They are often discussed together because they share this trait and because many foods that contain one also contain the other.

Each has several chemical forms, and each form carries a different name on labels. A little vocabulary goes a long way, so this guide walks through the names first, then the foods, then the units.

The letters were assigned in order of discovery, which is why the alphabet seems scattered. Vitamin A was named in the early twentieth century, and vitamin D followed soon after as researchers identified more oil-soluble factors in foods like cod liver oil.

The forms of vitamin A

Vitamin A is a family of compounds. The ready-made forms, called preformed vitamin A, include retinol, retinyl acetate and retinyl palmitate. They are found in animal foods. The plant forms are carotenoids, pigments such as beta-carotene that give carrots and sweet potatoes their orange color. Carotenoids are called provitamin A because they are the raw material from which vitamin A forms are made.

On a supplement label you may find vitamin A written as retinyl palmitate, retinyl acetate, beta-carotene or a combination. The wording in parentheses tells you which form was used.

Retinyl palmitate is the form most often chosen for gummies and other chewable products, because it is stable and mixes well into oil-based ingredients. Beta-carotene is chosen when a maker wants a plant-sourced form, and the label will say so in parentheses.

Some labels split the vitamin A line into two parts, such as a total amount followed by how much of it is beta-carotene. If you meet a line like that, the second figure is a part of the first, not an extra amount.

Where vitamin A occurs in foods

Preformed vitamin A shows up in liver, eggs, butter, whole milk and fortified dairy products, as well as certain fish. Provitamin A carotenoids are plentiful in orange and dark green plant foods.

Commonly listed food sources include:

Carotenoids are interesting for label readers because they give color. The orange of a carrot and the deep green of kale both come from carotenoid pigments, and the same compounds are sometimes used as natural colorings in packaged foods, where they appear as beta-carotene on the ingredient list.

• Beef liver and other organ meats
• Eggs and dairy products
• Carrots, sweet potatoes and winter squash
• Spinach, kale and other dark leafy greens
• Cantaloupe, mangoes and apricots
• Red peppers

The forms of vitamin D

Vitamin D comes in two main forms. Vitamin D2 is called ergocalciferol and is found in mushrooms that have been exposed to ultraviolet light. Vitamin D3 is called cholecalciferol and is found in animal foods. Both appear in supplements and fortified foods, and labels write them as vitamin D2, vitamin D3 or simply vitamin D followed by the form in parentheses.

Some D3 used in products comes from animal sources, while some is derived from lichen, a plant-like organism. Labels that mention a vegetarian source will say so.

Where vitamin D occurs in foods

Few foods contain vitamin D naturally in meaningful quantities, which is why fortified foods are common in this category. Oily fish and egg yolks are the best-known natural sources.

Foods listed in nutrition references include:

Because so few foods contain vitamin D naturally, fortified products carry much of the listing in the food supply. Packages of milk, plant-based drinks and breakfast cereals usually state it on their nutrition panel.

• Salmon, trout, sardines and mackerel
• Egg yolks
• Beef liver in small amounts
• Mushrooms exposed to ultraviolet light
• Fortified milk, fortified plant drinks and some cereals and yogurts

Decoding mcg, RAE and IU

Units are the trickiest part of these two vitamins. Current United States labels list vitamin A in mcg RAE, meaning micrograms of retinol activity equivalents. RAE is a unit that converts the different forms of vitamin A onto a common scale, because a microgram of beta-carotene does not count the same as a microgram of retinol. Vitamin D is listed in mcg, and sometimes IU, or international units, in parentheses.

One mcg of vitamin D equals 40 IU. For vitamin A, the conversion depends on the form, so the label is the best guide. Older products may show only IU, so confirm which system a label follows.

It can help to keep a small conversion fact in your head: 1 mcg of vitamin D is 40 IU, and 25 mcg is 1,000 IU. With that pair of figures you can translate most vitamin D lines without a calculator.

Vitamins A and D in LumiVelle

Both vitamins are named ingredients in LumiVelle, a daily gummy dietary supplement that also names Korean gelatin, PDRN, resveratrol, vitamin C, vitamins E, B6 and B12, folate, biotin, pantothenic acid, iodine and zinc. Each bottle holds 30 gummies, with a suggested use of one gummy daily, preferably with a meal, or as the label directs.

The exact forms and amounts are printed on the Supplement Facts panel on the bottle.