We’ve heard about nutrient deficiencies in children before, but unfortunately many toddlers are still at risk - of iron and vitamin D deficiencies in particular.

Infants and children have high iron needs for their physical growth, brain development and mental functioning. Vitamin D is important in infants as it helps the body absorb calcium, which in turn promotes bone mineralisation (hardening of the growing skeleton). Low iron levels in infants can go unnoticed as the symptoms take quite a while to show up – but when they do, fatigue and weakness, pallor (paleness), decreased appetite, irritability, impaired learning ability, headache and lowered resistance to infection are common.

Poor levels of vitamin D in infants reduce the amount of calcium that can be incorporated into growing bone, which can cause ‘soft bones’ or bone growth deformities such as rickets (leg bones that become misshaped).

Studies have found that iron and vitamin D deficiencies in infants and children can be strongly influenced by the mother’s own nutrition during pregnancy. Also, the risk of iron deficiency increases in toddlers aged six to 23 months if they have low vitamin D levels.

A lot of infant nutrition studies have been Auckland-based, but it does seem reasonable to use the information gathered as a basis for all those at increased risk, especially for Pacific and Maori populations, and other ethnic groups.

Iron deficiency found worldwide

Iron deficiency is the most common nutrient deficiency in the world. It affects one in four infants (25%) worldwide. A recent study of six to 23-month-old children in Auckland showed iron deficiency in 14% of those studied, compared with rates of 7% in Sydney, the US and Europe. The most important risk factor for iron deficiency was inappropriate milk feeding, which includes breast, infant formula and unmodified cow's milk. The rates of iron deficiency were also noted to differ among ethnicities – 20% in Maori, 17% in Pacific people, 27% in ‘other ethnicities’ and 7% in New Zealand European.

Infants are born with adequate iron stores which last until about the age of six months, when the infant’s need for iron increases rapidly. Supplementary iron from dietary sources is required at this stage for both breastfed and formula-fed infants. Inadequate iron in the diet is the main cause for iron deficiency.

Iron deficiency anaemia is a result of the progression from depleted iron stores in the body to iron deficiency, if not corrected. It can take years for symptoms to develop; therefore, ensuring adequate iron from dietary sources, along with a balanced diet, is the main way to prevent the problem.

Symptoms of iron deficiency include fatigue and weakness, pallor, decreased appetite, irritability, impaired learning ability, headache and lowered resistance to infection. Studies show the resulting mental disadvantages from iron deficiency anaemia in infancy can persist through childhood and adolescence, despite treatment.

Haem iron (from animal food sources) is easily absorbed and used by the body, while non-haem iron (grain and vegetable sources) is used less well by the body (see table below for examples). The absorption of non-haem iron is affected by other foods eaten around the same time; as an example, vitamin C (eg, in fruit and green veges) and haem-iron foods can aid non-haem iron absorption; while tannins (eg, in tea) and large intake of phytates (eg, present in grains and cereals) can reduce non-haem iron absorption.

Food sources of iron

Vitamin D deficiency

Vitamin D deficiency and nutritional rickets have re-emerged as health issues in Australian and New Zealand infants. Children in Auckland who were diagnosed with vitamin D-deficiency rickets had dark pigmented skin. Low vitamin D status has been found in infants and toddlers of Pacific and Maori ethnicities.

Most of the body’s vitamin D is produced by the effect of sunlight on the skin; therefore, the major source of vitamin D is sun exposure, although there are amounts of vitamin D in foods such as eggs, oily fish and some meats. It is known that dark skin pigmented individuals, and those who cover up while outdoors (eg, for cultural reasons), are most at risk of vitamin D deficiency. Infants with darker brown-pigmented skin need more sun exposure than pale-skinned infants to produce enough vitamin D. In summer (early Oct to late Mar), a few minutes sun exposure each day before 11am or after 4pm is generally a safe and adequate way to get adequate exposure. In winter, sun exposure during the middle of the day is less risky due to the sunlight being less intense in winter.

Breast milk, while on the whole very beneficial for the baby, can be a poor source of vitamin D, particularly if the mother is vitamin D deficient. Infants who are breastfed exclusively, particularly beyond six months and without sunlight exposure and vitamin D supplementation, are at risk for this deficiency. Parents are advised that vitamin D is usually obtained in sufficient quantities if there is appropriate and adequate sunlight exposure outside of the peak sun strength periods (11am to 4pm, early Oct to late Mar). Food sources of vitamin D should also be provided (see below).

Advice for parents

IRON
Infants from birth to 6 months:

• Breastfeeding is encouraged – iron from breast milk is highly bioavailable (easily absorbed by the body) despite its low concentration.
• Infants who are given infant formula at birth or who are no longer breastfed should receive an iron-fortified infant formula until 12 months of age.

Infants from 6–12 months:

• Iron-fortified infant cereal, vegetables and fruits should be introduced, followed by meat.
• Infants who are exclusively breastfed are recommended to continue and dietary iron should be introduced (in conjunction with breastfeeding).
• Do not introduce cow’s milk to infants who are under one-year-old.
• Diets high in fibre can inhibit iron absorption. Do not give wholegrain or wheat bran to infants under one-year-old.

From 12 months and young children:

• 600ml of cow’s milk is enough. Toddler milk or toddler formula could be considered for those who may benefit from additional nutrients.
• Include iron-rich foods daily.
• Tannins in tea inhibit iron absorption. Do not give tea to infants or young children.

General tips on iron intake:

• Offer fruit at mealtimes to improve the body’s ability to absorb iron.
• Include foods rich in vitamin C to help improve iron absorption (especially for non-haem iron sources). Vitamin C sources include cabbage, broccoli, tomato, kiwifruit, red and yellow capsicum, feijoas, citrus fruits* (eg, oranges, mandarins, lemon), mango, rock melon. [*Citrus foods should not be given to infants under eight months old.]
• Other iron/vitamin C combo ideas include beef mince cooked in tomato sauce (real tomato!), a squeeze of orange juice in cereals, meat/lentil stew with vitamin C-rich vegetables, lentil citrus (orange slices) salad with wholemeal bread.

VITAMIN D

• Sunlight is needed for adequate vitamin D. Children should be encouraged to play outside all year round. However, between early October and late March when ultraviolet light levels are high, most children will get sufficient vitamin D if playing outdoors for 10-15 minutes either side of the peak sun hours (11am to 4pm). It is not advisable to deliberately seek sun exposure during peak sun times.
• Food sources of vitamin D include eggs, especially egg yolk; fatty fish, eg, salmon, tuna, herring; vitamin D-fortified milk and margarine; especially in infants and children who are at risk of vitamin D deficiency.

Original material provided by Dr Marguerite Dalton, paediatrician and coordinator for National WellChild/Tamariki Ora and medical advisor to IMAC (Immunisation Advisory Centre); and Ada Cheung, community paediatric dietitian for the Community Child Health & Disability Service, Auckland DHB, and committee member of National WellChild/Tamariki Ora. Adapted from an article originally published in New Zealand Doctor newspaper. © 2007