Iron and iodine deficiencies are among the world’s most common nutrient deficiencies. Several local nutrition experts say iron, zinc, and potentially selenium, iodine, and vitamin D are worth highlighting.
University of Auckland nutrition associate professor Andrea Braakhuis said New Zealand’s last adult nutrition survey in 2009, along with subsequent research, suggests iron and zinc deficiencies are present, with some also reporting selenium deficiency — though not consistently.
A more recent pre-pandemic dietary survey analysed eating habits rather than deficiencies. While it had a large sample size, some groups carried a wide margin of error, says AUT emeritus professor of nutrition Elaine Rush.
From students living on tight budgets to families trying to make ends meet, canned foods can make meal time easier. But with more scrutiny over fats, sodium, and processing, how do they stack up?
Although surveys rely on self-reporting, they still provide useful population averages, Rush says. The 2009 survey also highlighted the need for multiple measurements to accurately assess deficiencies.
Why are these essential?
Deficiencies in essential vitamins and minerals can lead to health complications or “to less clinically notable reductions in energy level, mental clarity and overall capacity”, according to the World Health Organization.
Replenishment is necessary because these nutrients are constantly turning over in the body, Rush says. Nutritional needs also shift with age and circumstance, making public health messaging challenging, Braakhuis adds.
Micro-nutrients can be essential for various bodily functions, including metabolism, bone and muscle development and immunity. (file image)
Unsplash / Getty Images
Zinc supports metabolic pathways, immunity, wound healing, growth, appetite, and taste perception. It powers white blood cells to “clean up” inflamed areas, Rush says.
Iron is part of the proteins that transport oxygen in the blood and supply oxygen for muscle contraction.
Selenium contributes to antioxidant defence, thyroid metabolism, immune function, and reproduction.
Vitamin D is important for bone and muscle development, as well as immune function. Mild to moderate deficiency is often asymptomatic, while chronic deficiency can cause tiredness, muscle weakness, and bone softening.
Iodine is needed to produce thyroid hormones which regulate metabolism. Deficiency may cause dry skin, slow heart rate, tiredness, weight gain, constipation, depression, and high blood pressure.
Can’t I just take supplements?
Experts say supplements can help those who have deficiencies due to their diet or absorption issues, but for most others, they cannot replace a varied, whole-food diet. (file image)
Unsplash / Natalia Blauth
Supplements can be important for people with absorption issues, allergies, or restricted diets. But for most people, Braakhuis says food should come first.
“There’s so much of the industry which is driving the new food products and supplements and encouraging people to buy those things, but that’s not what works.” People often want a simple answer, but the reality is less exciting: you need to eat a variety of foods, Braakhuis says.
Rush agrees supplements cannot replace a varied, whole-food diet. New Zealand’s recommendation is five servings of vegetables and two of fruit a day.
“No way, by any stretch of the imagination, is anyone — or very few people — managing to do that. I work really hard at it, and I’m in a fortunate position of having enough money, but there’s many who don’t.”
Why do we have these deficiencies?
In March 2026 the price of mince recorded the highest annual increase since records began.
C Photos for Unsplash+
Initial findings from an unpublished dietary intake survey led by Braakhuis showed low consumption of red meat and seafood — both rich in iron and zinc — among a small group of New Zealanders.
Cost may be one factor, especially for red meat and seafood, Braakhuis says. Even before recent price rises, the pre-pandemic survey found adults in high-deprivation areas were less likely to meet vegetable and fruit recommendations. New Zealand’s dietary guidelines do not set a minimum intake for red meat or seafood but recommend no more than about 700–750g of red meat (raw weight) a week.
A table showing the 10-year Stats NZ Food Price Index difference of certain fruit, vegetable and meats.
RNZ / Stats NZ
Diet trends over the past two decades may also contribute, including potentially lower red meat consumption driven by health and climate concerns, Braakhuis says. The pre-pandemic survey found most adults did not exclude foods, but among those who did, seafood and red meat were the most commonly avoided. Just over a quarter of adults never or infrequently ate seafood, while 7.2 percent rarely or never ate red meat.
Vitamin D deficiency may also be linked to lifestyle. Because most vitamin D is synthesised through sunlight exposure, spending much of the day indoors — especially in winter — can be a factor, Braakhuis says. Ministry of Health data from 2024 showed a 45 percent increase in vitamin D supplement dispensing over the previous five years.
The 2009 survey noted that New Zealand-grown fruit, vegetables, and grains tend to contain lower selenium levels because of soil composition, though Braakhuis says some have refuted that as a link to deficiencies.
Iodine levels in New Zealand soils are also believed to be low, although a fortification programme is in place to reduce the risk. While some concern exists around people choosing Himalayan or other non-iodised salts, Braakhuis says it has not been widely reported as an issue in New Zealand.
So what foods can help?
Nutritionist Julie North says non-meat iron sources such as leafy greens and seeds are less well absorbed than haem iron from animal foods.
Nutritionist Julie North.
TIM WILLIAMS
She recommends pairing them with vitamin C-rich foods — such as kiwifruit or oranges — to improve absorption. Rush adds that while red meat is rich in iron, chicken legs contain more iron than chicken breast.
Zinc is more bioavailable in animal products, especially seafood and red meats, than plant foods. Phytates (which are a natural part of many plants) can bind to the zinc and reduce its absorption, North adds.
Few foods naturally contain vitamin D, and diet contributes only a small proportion of what we need. However, oily fish such as sardines, salmon, and tuna can help boost intake during short winter days, North says.
Canned lentils: iron and selenium
Red meat (lamb, beef, venison): iron and zinc
Salmon or canned tuna: vitamin D, iodine, selenium
Chicken liver pâté: iron
Frozen peas: vitamin C and iron
Eggs: iodine and selenium
Brazil nuts: selenium
Full-fat cow’s milk: calcium and zinc
Pumpkin seeds: iron and zinc
Use iodised salt in cooking; seafood such as seaweed and fish also provide iodine
From students living on tight budgets to families trying to make ends meet, canned foods can make meal time easier. But with more scrutiny over fats, sodium, and processing, how do they stack up?
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– Published by EveningReport.nz and AsiaPacificReport.nz, see: MIL OSI in partnership with Radio New Zealand
