Top 5 nutritional deficiencies in children in New Zealand and globally, and symptoms to look out for.

Nutritional deficiencies in children are very common, as periods of rapid growth and development can leave them vulnerable to nutrient depletion. This is especially a concern for children who have a limited diet, have gut and digestive issues which limit absorption, are physically very active and are fussy eaters. 

New Zealand soils also lack nutrients such as selenium, zinc, iodine, and magnesium, which means we cannot always rely on our food intake for adequate nutrition. In addition, children who have low immunity and are frequently sick with viruses often churn through and use up more nutrients every time they are sick and therefore have a higher demand for nutrients such as zinc, vitamin C, Iron, vitamin A and vitamin D.

It is important to swiftly identify and treat nutritional deficiencies in children, as long-term deficiencies can impair a child's growth, development, and cognitive abilities later in life. 'There is evidence that undernutrition in early childhood can affect cognition, language and social emotions, hinder later development and have a negative impact on human capital and economic growth' (1)

Nutritional deficiencies in children are a global burden as `In 2019, 161,847,936 children under 5 years of age suffered from nutritional deficiencies globally' (2)

Here are the Top 5 nutrients deficiencies commonly seen in children, symptoms to look out for and the richest food sources to include in your child's diet regularly.

Vitamin A

It surprised me that Vitamin A is the top nutritional deficiency seen in children in the world according to the World Health Organisation (WHO), mainly because it is not something that health agencies in New Zealand or many other western countries are talking about. 

The World Health Organization considers vitamin A deficiency the leading nutritional deficiency among children worldwide, affecting about 190 million preschool-age children. (3) This global statistic reflects the high number of children in developing countries (Africa and Southeast Asia) where malnutrition and a lack of beta-carotene-rich vegetables contribute to the problem.

Developed countries have traditionally not viewed vitamin A deficiency as a concern; however, it is becoming more and more prevalent in New Zealand children, especially with children that have gastrointestinal conditions and absorption problems, such as coeliac disease, and other inflammatory bowel conditions. Allergies, autoimmunity and digestive problems are on the rise as each generation appears to have a weaker immune system and more digestive issues than the previous generation, making them more vulnerable to nutritional deficiencies, especially fat-soluble vitamins like vitamin A. 

With vitamin A deficiency, even though the risk is lower in developed countries like New Zealand, it is still important to be aware of it as it is becoming more prevalent amongst vulnerable children. `Vitamin A is crucial for maintaining the function and integrity of the eye, immune system, skin and mucous membranes. Despite the scarcity of vitamin A deficiency developed countries, there are increasing reports of vitamin A deficiency in at-risk children, including those on the autistic spectrum or gastrointestinal conditions (4)

According to Dr Natasha Campbell McBride in her book Gut and Physiology Syndrome, children (and adults) with digestive issues and chronic inflammation cannot convert carotenoids from fruit and vegetables to the retinol form of vitamin A. `In people with digestive problems, such as GAPS children and adults, it is virtually impossible to obtain vitamin A from fruits and vegetables. The absorption rate of carotenoids can be less than 5%, which makes them largely useless as a form of vitamin A’. (5) In addition, to be able to convert carotenoids into the retinol form of vitamin A, the body needs sufficient iron, zinc, protein and fat, all deficiencies that commonly coexist with children with digestive issues. Intestinal parasites and an overgrowth of pathogenic bacteria in the gut can also affect the conversion.  

What are the most common deficiency signs of vitamin A in children?

Digestive problems - poor digestion can cause vitamin A deficiency and vitamin A deficiency can cause digestive problems (leaky gut, malabsorption issues) as vitamin A is important for the health of the intestinal lining.

Poor immunity - the earliest name for vitamin A was `anti-infective vitamin’ (6) which shows its importance in both innate (non-specific) and adaptive (specific) immune system response to bacterial and viral infections. ‘Children with vitamin A deficiency are prone to infections because their immune system does not function properly.  Infections, particularly with a high fever, destroy a lot of vitamin A in the body’ (7)

Night blindness and vision problems - this is the most common deficiency symptoms according to the World Health Organisation; however, it doesn’t always present as a symptom in children with vitamin A inadequacy.

Dry, scaly and itchy skin - vitamin A plays an important role in the maintenance of healthy skin and mucous membranes. Also, a weaker immune system makes the child more susceptible to bacterial and fungal skin infections. Eczema and keratosis pilaris can be a symptom of low vitamin A.

Low thyroid function - vitamin A is important for thyroid hormone production and the conversion of the inactive thyroid hormone T4 to the active thyroid hormone T3. Children can have thyroid issues as well. 

Food sources 

The richest food sources of vitamin A are organ meat (liver and kidneys) cod liver oil, eggs, daily products (especially butter) and oily fish. It is beneficial to aim to have at least one vitamin A rich animal food each day.

If your child has or is at risk of vitamin A deficiency, it may be beneficial to give your child half a teaspoon a day of cod liver oil (1 teaspoon per day for teenagers) as it contains natural vitamin A in its preformed biochemical form. This will provide sufficient vitamin A at safe levels.

It can be challenging getting children (and adults) to eat liver, so adding grated raw liver from the freezer to soups and dishes cooking on the stove can be a great way of sneaking it into food.

Beef liver capsules are also a great substitute and there are many brands available these days. 

It is important to eat foods rich in beta carotene such as bright yellow and orange vegetables such as carrot, pumpkin, capsicum and sweet potatoes. This is because in most people, the body can convert beta carotene to vitamin A and you can’t overdose on beta carotene, so it is safe to eat plenty of brightly coloured vegetables. As mentioned earlier, it is just kids with digestive and malabsorption issues who may struggle with this conversion.  

Iron

Iron deficiency is one of the leading nutritional deficiencies in the world, especially in developing countries, and can lead to iron deficiency anemia.

This shouldn’t be a surprise as organisations such as Beef and Lamb and Plunket are often spreading the message about iron deficiency, especially to parents of toddlers and young children. What may surprise you is the extent of how iron deficiency affects our children though, as it is not just about being tired.

According to the World Health Organisation (WHO), it is estimated that 42% of children under the age of 5 suffer from iron deficiency globally, and about 20% have iron deficiency anaemia. In New Zealand, 40% of infants and 1 in 5 toddlers are consuming inadequate amounts of iron and 14% of children under the age of 2 are iron deficient. A more recent First Foods New Zealand (FFNZ) study in 2023 estimated that 23% of infants aged 6.9 to 10.1 months exhibited suboptimal iron status.

Iron is an essential mineral that plays a vital role in various physiological processes that are important for the healthy development of children, especially in terms of energy production, brain development and cognitive function. It is a key component of hemoglobin, the protein in our red blood cells, that is responsible for transporting oxygen around the body.

Our infants and children are especially vulnerable to iron deficiency. This is because during the periods of rapid growth in infancy and early childhood, the body’s demand for iron significantly increases to support the expansion of blood volume and the growth of body tissues and organs. When body iron stores are depleted, this leads to a reduction in the production of red blood cells and hemoglobin, resulting in iron deficiency. Over time, this can lead to iron deficiency anemia which has more serious health consequences.

Out of all the age groups, the most vulnerable are infants, toddlers and teenage girls. The main reasons are:

• During growth spurts typical in childhood and adolescence, the body needs more iron to keep up with the extra demand during these periods of rapid growth.

• An insufficient intake of iron-rich foods, especially haem iron foods (such as red meat and poultry).

• An excessive intake of cow's milk (more than 350mls a day) can interfere with iron absorption and displace other foods because the child is full of milk.

• Gastrointestinal conditions such as coeliac disease or inflammatory bowel disease make it hard to absorb iron from food because of inflammation in the small intestine.

• Teenage girls may develop low iron if they have heavy periods.

  
  
  
  

Here are the common symptoms of iron deficiency:

• Tiredness and fatigue

• Feeling weak and dizziness

• Shortness of breath 

• Pale skin and nails

• Fast heartbeat or palpitations

• Slower growth and development, failure to thrive

• Problems focusing and concentrating

• Irritability and behavioural changes

• Brittle nails

• Thinning hair, hair loss

• Restless legs

• Sleep disturbances

• Cold hands and feet

• Wanting to eat unusual, non-food items such as dirt (pica) 

Sleep problems

Studies have revealed a link between childhood hyperactivity and sleep disturbances with low serum ferritin levels. These studies have shown that children with serum ferritin levels below 45ng/ml have more disturbed sleep than children with higher levels. Ferritin is a blood cell protein that contains iron. A ferritin test shows how much iron your body is storing, so if ferritin is low, it indicates iron stores are low and you have iron deficiency. Although this study was on children with ADHD, iron deficiency is a potential issue for any child with sleep problems.

Iron is essential for the synthesis and use of the important brain neurotransmitters dopamine, serotonin, adrenalin, and epinephrine. They are important for mood, emotion, focus, attention, and sleep.

If you are concerned your child may be low in iron, it is best to go to your GP and get a blood test done in the first instance. It is important to know what their ferritin level is.

What foods are a good source of iron?

Heme iron sources from meat, fish, and poultry have the highest absorption. Grass-fed beef, lamb, and liver are excellent sources. Plant sources of iron (non-heme) have a lower absorption, so should ideally be combined with animal sources for maximum absorption. Plant-based sources include spinach, lentil, beans, peas, apricots, prunes, raisins, molasses, tofu, and spirulina. Foods rich in vitamin C, such as potato, capsicum, broccoli, strawberries, and citrus fruits, help to increase the absorption of iron.

Zinc

One of the things I have noticed working with young children with gut issues, allergies, and development disorders is that many of them are severely deficient in the mineral zinc. With these children, I have supplemented with zinc as part of their treatment plans (after testing) and positive changes have occurred quite quickly.

The World Health Organisation (WHO) recognises zinc deficiency in children as a significant global health issue that can have multiple health consequences. Globally, according to WHO, the prevalence of zinc deficiency in children under 5 has decreased from 40% in 1990 to 22% in 2020. Despite this, Zinc deficiency remains a public health concern, with prevalence rates in some high-income countries exceeding 30% and exceeding 40% in low-income countries. The WHO considers a country to have a public health problem if the prevalence of low serum/plasma zinc is greater than 20%.

In terms of New Zealand, up to date national data is limited; however, a 2011 New Zealand national survey found that Pacific children aged 5-15 years had a higher prevalence of low serum zinc levels (21%) compared to Māori children (16%) and NZ European and other children (15%).

The importance of zinc

Zinc is a trace mineral that is involved with over 300 enzyme reactions in the body connected to growth, metabolism and digestion. Zinc is not stored for long periods of time in the body, so we need to have a daily supply of zinc from food in our diet as our soils in New Zealand have low levels.  As zinc is a trace mineral, we only need a small amount each day. The Recommended Dietary Intake (RDI) for children aged 7 months - 3 years is 3mg, age 4 - 8 is 4mg and age 9 - 13 is 6 mg per day.

Zinc is important for the following functions in the body:

• Proper immune function and fighting off infections

• DNA and protein synthesis - zinc is important for creating proteins and genetic material

• Growth and development, zinc plays a key role in cell growth and division, which is why it is so important in childhood

• Gut health and the digestion and absorption of food

• Mental clarity and function

• Skin health and healthy hair growth

• Wound healing, zinc is necessary for tissue repair and the healing of wounds

• Taste and smell - zinc is important for the normal function of our taste buds and senses

  
  

What are the consequences of zinc deficiency in children?

Zinc plays an important role in the growth and development of a child. It is a trace mineral that is present in the brain and contributes to its structure and function. Recent evidence suggests that zinc deficiency may be associated with deficits in activity, attention, and motor development. In children (and adults) severe zinc deficiency can cause abnormal brain function and impair behavioural and emotional responses.

Here are some of the common signs of zinc deficiency in children:

• Failure to thrive

• Diarrhoea

• Behavioural changes

• Neurological disorders

• Motor development and coordination issues

• Poor attention span and hyperactivity

• Sleep disturbances

• Anxiety and depression

• Low immunity - repeated infections

• Low appetite

• Fussy eating, due to trouble tasting food as a result of loss of senses of taste and smell

• Hair loss

• Poor wound healing

• Skin conditions such as eczema, psoriasis and acne

• Allergies

• White spots on fingernails

  
  

The following infants and children are more at risk of zinc deficiency:

• Infants who are born prematurely, as the majority of the baby's zinc stores are accumulated during the third trimester

• Infants and children who have issues with absorption due to gastrointestinal problems such as coeliac disease, Crohn's disease and inflammatory bowel disease.

• Infants and children with chronic diarrhoea

• Infants and children with allergies

• Infants and children who have inadequate dietary intake of zinc and/or consume a lot of phytate rich foods (such as wholegrains, nuts and legumes), which block the absorption of zinc

• Infants born from a mother who was zinc deficient during pregnancy and breastfeeding because of her inadequate dietary intake (e.g. vegan, vegetarian) or gastrointestinal issues (poor absorption)

• Teenage males are at more at risk of zinc deficiency (23%) than females (6.4%) due to their higher growth needs, according to research from the University of Otago. (8)

So what are the best food sources of zinc?

If you think your baby or child may be deficient in zinc the best course of action is to try to increase their dietary intake where possible, although it can be easier said than done if they have a low appetite or have a tendency to be fussy with food, which is a zinc deficiency sign due to an impaired sense of taste and smell. The best food sources of zinc are pumpkin seeds (great ground into smoothies or used in baking) grass fed beef, lamb, pork, chicken, cashew nuts, chickpeas, mushrooms, yoghurt and spinach.

If zinc deficiency results from poor absorption due to gastrointestinal issues, then improving digestive function and healing the gut lining are also important.

For children needing extra supplementation, I recommend Clinicians Zinc Oral Drops, which can be added to food and drinks. This product is safe to take from age 1 upwards using the recommended dosage listed on the bottle.

Magnesium

Magnesium is a very important macro (major) mineral that is required daily by our bodies in quite substantial amounts. Yet it is recognised as one of the most common nutritional deficiencies in the world affecting as many as a third of the general population, although specific data from the World Health Organisation (WHO) is limited. A deficiency of magnesium can lead to a number of health complaints, especially in relation to stress, sleep problems, cramps, and energy levels.

Magnesium is crucial because it is involved in over 400 metabolic and enzymatic functions in the body. So, when a person is deficient in magnesium, they effectively have 400 metabolic functions that are not working efficiently. This ultimately leads to dysfunction and disease, as the body struggles to maintain homeostasis (a healthy balance) without this important mineral.

Children are just as at risk of magnesium deficiency as adults, especially sporty kids, and teenagers who spend hours a week competing and doing strenuous training.

Here are some of the factors that may contribute to magnesium deficiency in children:

The soils in New Zealand are deficient in magnesium (amongst other important minerals such as selenium and iodine). In addition, 80% of magnesium is lost through food processing.

Foods that are good sources of magnesium such as nuts, seeds, legumes, avocado, and leafy greens are not consumed enough in the modern diet, especially by children and teenagers.

A diet high in refined sugar and carbohydrates depletes our magnesium levels as it causes the body to excrete magnesium through the kidneys.  It takes 56 molecules of magnesium to digest each molecule of sugar. This means that the challenge to get adequate magnesium from dietary sources is compounded further because of the overconsumption of sugar depleting magnesium from the body. To adequately process each consumed molecule of sugar, our body needs 56 molecules of magnesium.

It is well known that stress depletes magnesium levels. When we are under stress, we have an increased metabolic need for certain vitamins and minerals, especially magnesium, and as a result, our stores are rapidly used up and depleted. 

Sporty kids and teenagers have a higher need for magnesium because a lot of magnesium is excreted through sweat and more is used up for energy production, carbohydrate and fat metabolism, protein synthesis, and the healing of muscles.

Certain chronic conditions, such as Crohn's disease, coeliac disease and type 1 diabetes, can affect magnesium absorption.

Children who are fussy eaters may not be eating enough magnesium-rich foods.

The Recommended Dietary Allowances (RDA) according to the `Nutrient Reference Values of Australia and New Zealand' (9) are:

1 - 3 years (boys and girls) - 80 mg per day

4 - 8 years (boys and girls) - 130 mg per day

9 - 13 years (boys and girls) - 240 mg per day

14 - 18 boys 410 mg per day

14 - 18 girls - 360 mg per day

Here are some common signs that your child might be deficient in magnesium:

• Frequent headaches and migraines (also check for dehydration)

• Muscle cramps, tingling, twitches (e.g., eyelids), restless legs

• Growing pains

• Anxiety, tension, irritability

• Insomnia and difficulty falling asleep

• Hyperactivity, inability to relax

• Abnormal heart rhythm and palpitations

• Low energy and fatigue

• Chronic constipation, nausea

• Loss of appetite

Good food sources of magnesium are almonds, Brazil nuts, pumpkin seeds, sunflower seeds, leafy greens (kale, spinach) bananas, chickpeas, beans, shrimp, raw cacao, and dark chocolate. So, try to encourage your child to eat as much of these foods as possible.

Also, regular baths in Epsom Salts, which are made from the mineral’s magnesium and sulfate, which have a number of health benefits and are absorbed directly into the skin, so you notice a calming effect straight away. 

If your child or teenager is eating a lot of these magnesium-rich foods and still have some of the symptoms listed above, then they may benefit from an additional magnesium supplement that has magnesium glycinate, aspartate, or citrate as these are the well-absorbed types of magnesium. Where possible, avoid supplements with magnesium oxide as absorption is very low, so it is not great at increasing magnesium levels, but it does, however, work well as a laxative for constipation.

Vitamin D

Vitamin D deficiency is a significant public health concern both globally and here in New Zealand, and children are especially vulnerable.

Globally, it is estimated that 30 - 50% of children worldwide may have vitamin D deficiency. In New Zealand, recent national surveys have indicated that one in three New Zealand children had too little vitamin D in their blood. It seems to be especially prevalent in early childhood in New Zealand, as a study in Auckland found that 10% of young children in early childhood were vitamin D deficient. (10)

Cholesterol is the major building block of vitamin D. When our skin is exposed to sunlight, vitamin D is synthesised from cholesterol in our skin. This is one of the reasons why foods that are naturally rich in cholesterol such as butter, eggs, oily fish and liver are an important part of our diets, although it is often challenging to get enough vitamin D from dietary sources alone. 

Vitamin D levels are generally lowest during the winter months and early spring in New Zealand. If we spend enough time out in the sun on a daily basis, most of us could make enough vitamin D. However, many of us do not get enough consistent sun exposure to maintain normal vitamin D levels throughout the year, with levels dropping over the wintertime.

Where possible, try to encourage your child to spend 10 - 15 minutes every day out in the sunshine with no sunscreen throughout the year. In summer, it is best to avoid the heat of the day so before 10.00am and after 3.00pm is the best time. In the winter, aim for at least 1 hour in the sun to manufacture enough vitamin D, although this is often challenging with it getting dark earlier. In wintertime when there isn’t much sunlight, vitamin D production drops so we have to pay more attention to our diet, making sure we consume plenty of foods that are rich in vitamin D. These are cod liver oil, oily fish such as salmon and tuna, eggs, butter and liver.  In the wintertime, if you child is not getting out in the sun much or eating these cholesterol-rich foods then additional supplementation may be required as ‘other than sunlight and cholesterol-rich foods, there is no other appropriate way to get vitamin D’ (11)

What are the risk factors for vitamin D deficiency in children?

A lack of sun exposure - this is often due to time spent indoors and reduced UVB exposure due to use of sunscreens, hats and protective clothing for the whole time spent outdoors (i.e no exposure to the sun without sunscreen).

Breastfed infants - as breast milk alone is not a rich source of vitamin D, those who are exclusively breastfed are at a higher risk of vitamin D deficiency, especially if mum is also vitamin D deficient.

Maternal vitamin D status - a baby’s vitamin D levels are linked to their mother’s levels during pregnancy. So, if mum is vitamin D deficient, the baby is at risk, especially if they are exclusively breastfed.

Ethnicity and skin colour - children with darker skin colour, including many from Africa, the Indian subcontinent and the middle east are at a greater risk of vitamin D deficiency as they have less efficient vitamin D production from sunlight due to the high melanin content.

Chronic health conditions - children who have been diagnosed with health conditions such as Crohn's disease, coeliac disease, cystic fibrosis, kidney disease and asthma are at higher risks as these conditions can affect the absorption and metabolism of vitamin D.

Autoimmune conditions - A deficiency in vitamin D3 has been associated with various autoimmune conditions such as rheumatoid arthritis, type 1 diabetes, lupus, inflammatory bowel disease, coeliac disease and psoriasis as it has a regulatory effect on the immune system.

Here are the key symptoms of vitamin D deficiency in children:

• Rickets

• Muscle weakness

• Poor Immunity

• Chronic infections

• Weak bones, bone pain

• Tingling in hands and feet

• Tiredness and fatigue

• Growth and development issues

• Digestive issues

• Asthma

The New Zealand Ministry of Health recommends supplementing with vitamin D for those vulnerable to vitamin D deficiency, in particular:

• All exclusively or partially breastfed infants up to age 1 year. There are specific baby vitamin D liquid supplements on the market with a dose of around 400iu per day. (12)

  
  

• Pregnant women who are at risk of deficiency (e,g winter pregnancy, darker skin, coeliac disease, asthma, etc). Taking 1,000–2,000iu per day is a standard dose. However, an increased dose may be required if test results show that vitamin D is low.

  
  

• Children with a diagnosed vitamin D deficiency or have a medical condition which increases their risk. 400iu per day from birth to age 3, then 1,000 iu per day from age 3 onwards.

In summary, vitamin A, iron, zinc, magnesium and vitamin D are the most common nutritional deficiencies worldwide and in New Zealand. If you are concerned that your child may have a nutritional deficiency based on any of these symptoms, in the first instance look at optimising dietary sources by increasing the foods that have the richest source of the nutrient.

Your child may also benefit from targeted nutritional supplements depending on your child's symptoms and diet. For further support, I offer a FREE 15-minute consultation via Zoom, a casual space to chat about your child’s situation and how I may be able to help you.

References

(1)       Yue T et al. Global burden of nutritional deficiencies among children under 5 years of age from 2010 to 2019. Pubmed, 2022, June @8, 14 (13), 2685

(2)       Yue T et al. Global burden of nutritional deficiencies among children under 5 years of age from 2010 to 2019. Pubmed, 2022, June @8, 14 (13), 2685

(3)       World Health Organisation. Vitamin A supplementation in Infants and Children 6–59 months of age. Intervention, 9/8/23. www.who.int.  

(4)       Song A et al. Recognising vitamin A deficiency: special considerations in low prevalence areas. Curr Opin Pediatr, 2022, April 1, 34 (2) 241 – 247

(5)       Cambell McBride Dr N,  Gut and Physiology Syndrome, P 332, 2020, Medinform.

(6)       Cambell McBride Dr N,  Gut and Physiology Syndrome, P 333, 2020, Medinform.

(7)       Cambell McBride Dr N,  Gut and Physiology Syndrome, P 333, 2020, Medinform.

(8)       Forshaw D. Dietary intake, adequacy and food sources of zinc in New Zealand adolescent males and females. 2021, University of Otago. Ourarchieve.otago.ac.nz

(9)       Grant C C et al. Vitamin D deficiency in early childhood: prevalence in the sunny South Pacific. Cambridge University Press, Vol 12, issue 10, October 2009.

(10)    Cambell McBride Dr N,  Gut and Physiology Syndrome, P 334, 2020, Medinform.

(11)    Bpac NZ. Vitamin D supplementation: an update. Bpac.org.nz