More than one in five Australians overall are deficient in vitamin D while approximately two million are iron deficient.
Women are more likely to lack iron than men due to blood loss in menstruation and having higher iron requirements.
Iron supports energy and immune functions by helping produce haemoglobin, which carries oxygen in the blood, and is stored as ferritin.
Up to 15 per cent of non-pregnant women and nearly 12 per cent of those with child are iron deficient.
Girls between 14 and 18 are particularly vulnerable, with 40 per cent falling short of the recommended intake.
Fatigue, mood swings, frequent illness, breathlessness, poor concentration and slowed growth in children can all be linked to iron deficiency.
Sydney mum-of-six Stephanie Saunders initially dismissed her symptoms of tiredness, brain fog and constant illness to be the result of a busy life juggling work and parenthood.
"I left it way too long but when I got sick for the fourth time in a matter of months, I realised enough was enough because I couldn't think straight," she told AAP.
An at-home test taken via a finger prick revealed Ms Saunders was low in both ferritin and vitamin D and pushed her to see a doctor.
She was advised to change her diet to more iron-rich foods like legumes and red meat, and take supplements.
"It was a wake-up call that even when you think you're doing everything right, deficiencies can still sneak up on you," she said.
"My message is not to wait until you're at breaking point. You have to listen to your body and put your health first."
For many Australians, vitamin D levels are at their lowest at the end of winter or early spring, as it depends on sunlight exposure, which can be reduced during winter.
But increased SPF use and more time indoors mean vitamin D production can still lag behind in summer.
Early testing is vital to ensure people can access effective and long-lasting treatment, Touch Biotechnology chief executive Matthew Salihi said.
"You don't feel a deficiency arrive suddenly, it creeps in quietly, often worsening through the colder months when energy levels naturally dip," he said.
"It's not always obvious where the symptoms come from (and) people often dismiss low energy or mood as stress, lack of sleep or lifestyle changes, yet a deficiency could be the hidden cause."
