An introduction to vitamins

In this article, we’re going to take a closer look at micronutrients. These are essential nutrients that we need in small amounts for multiple tasks in the body. Micronutrients include vitamins and minerals.

First up, vitamins.

What are vitamins?

There are a number of different vitamins, each having specific roles in keeping us healthy. We all need vitamins but the amounts we need may vary, dependent on our age and sex.

We can divide vitamins into two categories – fat-soluble and water-soluble. Which category the vitamin is in tells us a number of things about it – it gives us clues as to how best to obtain the vitamin in your diet, how the vitamin will be transported through the body and whether or not it may be stored for future use.

Fat-soluble vitamins

Fat-soluble vitamins include vitamins A, D, E and K. As their names suggest, these vitamins are soluble in fats or oils – so they are often found in foods that contain some fat – avocado is a good source of vitamin E. Being fat-soluble these vitamins can be stored for future use in our fat tissue as well as in organs, like the liver.

Let’s take a closer look at one of these fat-soluble vitamins and explore how we can best achieve optimal levels.

Fat-soluble vitamin A

This is derived from our food in two forms. In animal foods we obtain vitamin A as retinol, this is known as the ‘active’ form because it’s the form our body recognises and can readily use. Plant foods supply vitamin A as beta-carotene, which is often referred to as pro-vitamin A because it must be converted by the body into the active form.

We need vitamin A for a number of functions including helping our eyes to adjust to the dark. The skin, eyes and mucous membranes of the mouth, nose, throat and lungs all need vitamin A to keep them moist and healthy and defend us from infection. Vitamin A, along with vitamin E, is antioxidants – more about these later.

Useful food sources of vitamin A include:

• milk, with whole fat milk being naturally richer than unfortified skimmed milk
• orange and green vegetables
• oily fish.

We can optimise our absorption of pro-vitamin A from fruit and vegetables by combining foods rich in pro-vitamin A, like carrots, with a knob of butter or an oil dressing. It’s worth bearing in mind that if you follow a very low-fat diet your intake of these important fat-soluble vitamins may not be adequate for your needs.

Water-soluble vitamins

_{Water-soluble B vitamins are found in a wide range of foods, including fish}

Now let’s take a closer look at water-soluble vitamins.

As their name suggests, these vitamins, which include the B group of vitamins and vitamin C, are soluble in water. This means they are prone to lose during cooking – for example when we boil vegetables. Water-soluble vitamins are also less likely to be stored in the body for future use, that’s because any excess is likely to be excreted in our urine.

B group of vitamins

There are eight B vitamins including thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate and cyanocobalamin (B12). These B vitamins are found in a wide range of foods:

• eggs
• poultry
• fish
• grains and legumes.

A couple of B vitamins require special mention. If you’re planning to start a family or are a mum-to-be you need to ensure adequate folate levels in order to avoid birth defects. Those on a vegan diet need to be aware that vitamin B12 is not found in plant foods so fortified foods or supplementation may be necessary. Older adults may find vitamin B12 harder to absorb as they age.

Vitamin C

The other water-soluble vitamin, vitamin C prevents illness, supports skin and bone health and helps keep blood vessels healthy. Typically, vitamin C is found in:

• citrus fruits
• strawberries
• peppers
• green vegetables
• potatoes.

Water-soluble vitamins, like vitamin C, are easily destroyed by lengthy periods of storage or pro-longed cooking and are lost in the water both used to prepare and cook the vitamin-rich foods.

Storing these foods correctly and for a minimal amount of time is best – when buying fresh aim to buy the amount you need rather than bulk buying. Store fresh fruit and vegetables whole rather than pre-chopped or diced, and in the chiller drawer of a refrigerator, keeping fresh items away from direct light.

If you boil vegetables you are likely to lose some of their water-soluble vitamins in the cooking water, so use the minimum amount necessary and save it to add back to recipes.