Some vitamins and minerals are needier than Britney. Taking them without their significant others – known in the biz as ‘co-factors’ – can make them next to useless.

Vitamins - the essential guide - Women's Health & Fitness

“Some nutrients compete with others, so by taking one supplement, you may cause yourself a deficiency in another,” says accredited practising dietitian Melanie McGrice, of nutritionplus.com.au.

And according to the head of Evelyn Faye nutrition, former pharmacist Ian Collins, certain medications can mess up the mechanics of some supplements worse than a DIY buzz-cut. Likewise, some nutrients, whether in food or pills, can undermine certain meds.

With four million Australians knocking back vitamin and mineral pills at last count, the scary part is that most vitamin and mineral supplements are purchased over the counter – or even online – with varying degrees of expert advice. Collins insists on staffing his business with qualified naturopaths, but the same may not be true when you load your trolley at a discount chemist. His advice? Always ask an accredited nutritionist or naturopath for further advice before taking nutritional or herbal supplements, and ask a pharmacist or doctor about medication clashes.

And don’t think natural means no worries. Even greens and grapefruit can cause havoc with some medicines. Finally, don’t mistake a bottle of magnesium for a license to subsist on frozen meals. “Always check the brands, doses and types of nutritional supplements with your dietician and choose food over supplements whenever possible,” McGrice concludes.

ZINC (Zn)
This is one of the most common supplement staples, zinc’s a little sensitive when it comes to absorption, with many common factors causing excessive loss of zinc. Think stress, alcohol, cigarettes, gastrointestinal and digestive disorders and chronic diarrhoea.

CARE FACTOR: Deficiency can be associated with acne, brittle nails, impaired wound healing, loss of taste and smell, low sperm counts, poor concentration, increased incidence of colds/flus.
DAILY DOSE: The RDI for Australian adults is 8-14mg/day.
ON A PLATE: Shellfish, red meat, eggs, milk, sunflower seeds, whole grains. Oysters are the richest source of zinc, with one oyster (50g) providing around 8mg of zinc.
ENEMIES: Excessive calcium impairs zinc levels, as they both compete for absorption. The same is true for iron. Alcohol and some prescription meds may also inhibit zinc absorption.

MAGNESIUM (Mg)
An essential mineral involved in over 300 metabolic reactions including energy production, magnesium is one of the most widely used supplements, especially among athletes. According to Collins, it’s used in every muscle movement and nerve conduction. Exercise increases the body’s demand for magnesium as it’s excreted through sweat.

CARE FACTOR: According to Collins, “most people are low in magnesium, especially as you get older; magnesium becomes more and more important, with its role in preventing muscular cramps and maintaining heart health”. Deficiency signs include anxiety, cold hands and feet, chronic fatigue, cramps, irregular heartbeat, hypertension, insomnia, PMS, poor growth and vertigo.
DAILY DOSE: RDI for Australian adults is 310-420mg/day.
ON A PLATE: Almonds, barley, molasses, wholegrain cereals, kelp, eggs, seeds. Add ½ a cup of oat bran to your morning muesli or smoothie for extra 96mg of magnesium.
SABOTEURS: Similar to zinc. High levels of calcium or iron may compete with magnesium for utilisation. Excess consumption of caffeine and alcohol also prohibits the absorption of magnesium.

B MULTIVITAMIN
Metabolic function? Check. Stress relief? Check. But B Vitamins are water soluble, which means they are eliminated quickly, so you need to clue up on how to get the benefits before they disappear.

CARE FACTOR: A classic sign of B vitamin deficiency is “cracked lips” says Ian. Generally speaking symptoms such as lethargy, fatigue, poor immunity, sleepiness and weakness and mainly associated with a range of B vitamin deficiencies.
DAILY DOSE: RDI’s for Australian Adults are as follows:
B1 – 1.1-1.2mg/day; B2 –1.1-1.3mg/day; B3 – 14-16mg/day; B5–4-6mg/day; B6 – 1.3-1.7mcg/day; B12 – 2.4mcg/day.
ON A PLATE: The yeast found in vegemite, provides 0.5mg of B1, 0.85mg of B2, 5.8mg of B3 per teaspoon. If you fancy some offal, liver is a fantastic source of all the B Vitamins, especially B5 with 85g chicken liver providing 7mg. Tuna is a great source of Vitamin B6 with 100g serve providing over 1mg.  Vitamin B12 can only be found in animal products so often needs to be supplemented for vegetarians. 100g fillet of salmon provides more than your daily dose with 3.25mcg B12.
SABOTEURS: Excessive intakes of coffee, tea, alcohol, cigarettes and protein can reduce the absorption.

VITAMIN C (Ascorbic Acid)
This antioxidant is a fantastic all-rounder. It helps to boost immunity, assists in healthy teeth and gums, and promotes collagen synthesis for youthful skin, improves sperm health and piques wound healing. Collins recommends Vitamin C for your “immune system to fight infection and to be used in exercise as an antioxidant”.

CARE FACTOR: The human body lacks the ability to synthesise vitamin C, which means we depend on dietary sources or supplementation to meet vit C quotas. Common signs of Vitamin C deficiency include bleeding gums, fatigue and increased susceptibility to infection/colds. The official deficiency of Vitamin C is known as ‘scurvy’, which although uncommon, can still occur in adults and children and is characterised by irritability, leg pain, and loss of appetite, shortness of breath, fever, tissue haemorrhaging and pain.
DAILY DOSE: RDI for Australian adults is 45mg/day.
ON A PLATE: Vitamin C is abundant in fresh vegetables and fruits such as berries, guava, citrus fruits, kiwi fruit, broccoli and sprouts. Chillies are also bursting with Vitamin C, so add some heat to your next dish, with a single red chilli providing 65mg of Vitamin C!
SABOTEURS: Similar to other water soluble vitamins, vitamin C is unstable to heat and light and absorption is decreased from excessive coffee/tea, alcohol, cigarettes and aspirin.

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