About vitamins and minerals
Vitamins and minerals are organic compounds that our bodies use in very small amounts for a variety of metabolic processes. Basically, they keep us healthy and help our bodies to function.
We get vitamins and minerals from the foods we eat. For most of us, a healthy and varied diet (that includes all 5 food groups) is all we need to stay healthy. It is best to get vitamins and minerals from eating a variety of healthy unrefined foods.
Vitamins and minerals can cause toxicity if consumed in large amounts.
Types of vitamins and their functions
Vitamins and minerals are a form of nutrient (called micronutrients) that are needed in small amounts. Although micronutrients don’t give us energy, they are involved in the metabolic processes that enable us to get energy from carbohydrates, protein and fat, which are also known as macronutrients.
Different vitamins serve different purposes and contribute to different bodily functions. There are 13 vitamins in total and 8 of these come from the B-group of vitamins.
Vitamin A
Vitamin A is important because it:
- makes the immune system work effectively so it can fight disease and infections
- keeps our skin healthy
- supports reproduction and growth
- helps with vision.
Food sources of vitamin A
There are different compounds with vitamin A activity in animal and plant foods. Plant foods can be easy to spot as they tend to have orange/yellow pigment known as beta-carotene.
Plant sources include:
- orange and yellow fruit and vegetables – such as carrots, red capsicum, mangoes, sweet potatoes, apricots, pumpkin and cantaloupe
- leafy green vegetables – such as spinach, peas and broccoli.
Animal sources include:
- liver
- eggs
- some fortified milk and milk products (with added vitamin A).
Vitamin A deficiency risks
Because of the various roles that vitamin A plays in the body, deficiency can have several health effects. These include:
- increased risk of infections
- night blindness and irreversible blindness (xeropthalmia)
- excessive keratin build-up of the skin.
Vitamin B
B-group vitamins help our bodies use the energy-yielding nutrients (such as carbohydrates, fat and protein) for fuel. Some B-group vitamins are needed to help cells to multiply by making new DNA.
Except for B-12 and folate which are stored by the liver, most B-group vitamins can’t be stored by the body. They must be consumed regularly in a healthy diet that includes a range of wholefoods (such as lean meat, fish, wholegrains, fruit, vegetables and legumes) and limits the intake of alcohol and processed foods.
The 8 types of vitamin B are:
- thiamin (B1)
- riboflavin (B2)
- niacin (B3)
- pantothenic acid (B5)
- pyridoxine (B6)
- biotin (B7)
- folate or ‘folic acid’ when included in supplements (B9)
- cyanocobalamin (B12).
A person who has a poor diet for a few months may end up with B-group vitamins deficiency. For this reason, it’s important that adequate amounts of these vitamins be eaten regularly as part of a well-balanced, nutritious diet.
Vitamin C
Dietary intake of vitamin C (from food and drinks) is essential, because the human body cannot make this vitamin from other compounds. We also need to have vitamin C as a regular part of our diet because the body cannot store vitamin C for very long.
Vitamin C (ascorbic acid) is important for many metabolic processes, including:
- Collagen formation – collagen is used in different ways throughout the body. Its primary role is to strengthen the skin, blood vessels and bone. The body also relies on collagen to heal wounds.
- Antioxidant function– the metabolism of oxygen within the body releases molecular compounds called ‘free radicals’, which damage cell membranes. Antioxidants are substances that destroy free radicals, and vitamin C is a powerful antioxidant.
- Iron absorption – the process of iron absorption is aided by vitamin C, particularly non-haem iron (found in plant foods such as beans and lentils).
- Infection fighting – the immune system, particularly cells called lymphocytes, requires vitamin C for proper functioning.
- Other roles – vitamin C is used to produce other important substances in the body such as brain chemicals (neurotransmitters).
Dietary sources of vitamin C
Adults need about 45mg of vitamin C per day and any excess amount (above 200mg) is excreted.
Vitamin C is sensitive to heat, so some of its nutritional benefits can be lost during cooking. Raw foods are more beneficial as dietary sources of vitamin C. These include:
- fruit – oranges, lemons, limes, grapefruits, blackcurrants, mangoes, kiwifruits, rock melon, tomatoes and strawberries
- vegetables – particularly green vegetables (such as cabbage, capsicum, spinach, Brussels sprouts, lettuce and broccoli), cauliflower and potatoes.
Vitamin C deficiency and scurvy
A severe lack of vitamin C can lead to scurvy. We may think of it as a disease of the past, but it does still exist. Factors or lifestyle issues that may increase your scurvy risk include:
- regularly eating unhealthy foods
- crash dieting – especially being on diets that exclude certain food groups
- being malnourished due to inadequate care
- very strict allergy diets
- having an eating disorder
- smoking – smokers need more vitamin C to cope with the extra stress on their body.
Scurvy symptoms
The onset of symptoms of scurvy depends on how long it takes for the person to use up their limited stores of vitamin C.
Scurvy is usually easy to treat – symptoms are like many other mild complaints and may include:
- fatigue and generally feeling unwell
- loss of appetite
- nausea and diarrhoea
- fever
- painful joints and muscles
- small ‘pinpoint’ bleeding around hair follicles visible in the skin.
If you or someone you care for is at risk, please see your doctor.
Vitamin D
Vitamin D is important for strong bones, muscles and overall health. Ultraviolet (UV) radiation from the sun is necessary to produce vitamin D in the skin and is the best natural source of vitamin D.
Regular physical activity also assists with the body’s production of vitamin D.
The body can only absorb small amounts of Vitamin D.
Spending too much time in the sun may increase your risk of skin cancer. Remember to use daily sun protection, especially at times when UV index levels are at their highest (3 or above).
Food sources of vitamin D
Only a small amount (around 5-10%) of Vitamin D is sourced from our diet. Sources include:
- fatty fish (such as salmon)
- eggs
- margarine and some milks have added vitamin D.
Vitamin D deficiency
It is important to achieve a good peak bone mass early in life. Vitamin D deficiency can result in a decline in bone density in adult life, increasing the risk of:
- osteoporosis
- falls and bone fractures (especially for older people)
- rickets (in young children) – a preventable bone disease
Treatment options include improved sunlight exposure, diet, exercise, vitamin and mineral supplements.
If you are concerned about vitamin D levels, see your GP. Your GP may recommend vitamin D supplements, which should be taken strictly as directed.
Vitamin E
Vitamin E is an antioxidant that helps protect your body against damage from free radicals, such as exposure to cigarette smoke or radiation. It is also important for our:
- vision
- immune system
- skin.
Dietary sources of vitamin E
Vitamin E is best obtained from a healthy diet that contains plenty of fresh minimally processed foods. Vitamin E is also vulnerable to heat (especially cooking methods such as deep frying.
Dietary sources include:
- meats (e.