Vitamins are organic compounds that are essential to life and perform a range of different functions in the body. Modern day methods of food storage, processing and cooking, as well as our food and lifestyle choices can make it challenging to obtain sufficient quantities of these vital nutrients from our daily diet. In addition, certain factors can increase the body's requirements for particular vitamins, for example:
Pregnancy and breastfeeding – creates a higher overall need for nutrients to fulfil the nutritional requirements of the baby plus specific vitamins for certain purposes such as folic acid to help prevent spina bifida.
Regular alcohol consumption - alcohol depletes the body of many nutrients including B Vitamins and Vitamin C.
Cigarette smoking – smokers have been shown to have low Vitamin C levels in comparison to non-smokers.
Medications – certain medications can result in lowered levels of some vitamins for example the oral contraceptive pill can increase the need for B vitamins.
Advancing age – the elderly often have lowered digestive function, poor absorption of nutrients and are commonly deficient in B vitamins. Medications and health issues can also increase their requirements.
Vegetarians – can be at risk of Vitamin B12 deficiency
Food intolerances and allergies – needing to avoid particular foods can result in inadequate consumption of essential vitamins.
Digestive disorders - malabsorption conditions such as diarrhoea, coeliac disease or pancreatitis may result in lowered vitamin absorption.
Stress – increases the rate at which the body uses B vitamins and Vitamin C.
Vitamins are classified as either water or fat soluble depending on which medium they mix with. This also determines how the vitamin functions in the body. Water soluble vitamins include the B vitamins and Vitamin C, they act in the watery fluids of the body and need regular replacement. Vitamins A, D, E and K are fat soluble vitamins and are thus absorbed in the presence of dietary fat and act in fat-rich environments such as cell membranes. Taking high doses of fat-soluble vitamins for long periods of time is not advised as they can be stored in the body's tissues and potentially accumulate to toxic levels.
The B group vitamins include thiamin (Vitamin B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), Vitamin B12 and folic acid. Each individual B vitamin has its own specific roles, however overall the B vitamins work together to perform very similar functions. This synergistic action is the reason it is generally best to take B vitamins as a combined B complex when taking them in supplement form. Vitamin B12 requires the presence of intrinsic factor – a substance produced by the digestive system, for absorption. Lack of intrinsic factor can lead to B12-deficient or pernicious anaemia.
The primary functions of the B group vitamins include:
Digestion and metabolism
Healthy nervous system function and neurotransmitter production
Some examples of the unique roles of the B vitamins are:
Vitamin B6 is considered to help hormonal conditions such as PMS and morning sickness.
Folic acid taken at least 1 month prior to falling pregnant can help prevent spinal tube defects in the baby.
Folic acid and Vitamin B12 are important for healthy blood metabolism.
Vitamins B6 and B12 may help reduce symptoms of cognitive decline in the elderly.
Most people would know Vitamin C as the 'cold and flu' vitamin as its well known for its effects of helping to reduce the severity and duration of minor respiratory infections. Bioflavonoids are thought to enhance the absorption of Vitamin C and act together to help maintain capillary walls and prevent easy bruising and bleeding.
Some of the many roles of Vitamin C include:
Skin health and wound healing
Maintenance of connective tissue – essential for the formation of collagen found in the skin, blood vessels, tendons and cartilage.
Facilitates the absorption of iron
Vitamin A is found in animal sources such as meat, fish and dairy products. It is also found in cod liver oil, an old-fashioned remedy given daily by the spoonful to help keep the body healthy and strong. Cod liver oil also contains Vitamin D, and with both these vitamins playing a role in healthy immune function, it is no wonder that many people found this remedy really did keep the germs away.
Betacarotene is often referred to as Pro-Vitamin A as the body converts dietary betacarotene into Vitamin A as it is required. This conversion occurs by way of an enzyme found in the intestines and liver, and both zinc and vitamin E are important in this conversion. Betacarotene is found in many fruits and vegetables, with carrots being one of the richest sources.
The important actions of Vitamin A in the body include:
Eye health & vision
Lung & respiratory support
Vitamin D has received alot of attention over the last few years as many of its important functions have been discovered. Our body makes a form of Vitamin D on exposure of the skin to sunlight, hence its nickname "the sunshine vitamin". This inactive form is then converted to its active form Vitamin D3 by the liver and kidneys. Despite being the sunny country, research has shown that a large proportion of Australians have low Vitamin D levels. This has largely been attributed to both our sun protection strategies for skin cancer prevention as well as more time spent indoors. Vitamin D is only found in a small selection of foods – fatty fish, beef, liver, butter and eggs. This vitamin is still the subject of much scientific interest, but we already know it has a wide array of actions in the body such as:
- Assisting calcium absorption and metabolism and supporting bone health
- Maintenance of muscle strength
- Immune regulation
- Supporting healthy mood
Some of the conditions Vitamin D is thought to be beneficial for include autoimmune disorders, thyroid conditions and osteoporosis. The body's serum Vitamin D levels can be measured via a blood test.
Vitamin E, popular for its cardiovascular effects, is also known as alpha-tocopherol. It is naturally found in both animal and plant foods, with some of the richest sources being cold-pressed oils, nuts and seeds.
Some of the main functions of Vitamin E include:
- Healthy circulation & cardiovascular system
- Promotes a healthy immune system
- Aids skin repair and wound healing
Vitamin K is best known for its role in blood clotting as it is required for the synthesis of several of the cofactors and proteins necessary for blood coagulation. In fact, the letter 'K' in the name of this vitamin originally came from the German word koagulation. Dietary sources of Vitamin K include green leafy vegetables, blueberries and fermented foods. In addition, the beneficial bacteria in our intestines produce Vitamin K, though this supply only contributes a minimal quantity to our Vitamin K requirements.
Vitamin K roles:
Healthy blood clotting
Formation of healthy bone