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Nutrition Information   

Nutrition in early life stages

Good nutrition before, during and after pregnancy is essential for the health of the mother and for giving the baby the best possible start in life.

A healthy diet, based on the 10 key recommendations from the Hong Kong Department of Health,1 is a diet based on whole-grain foods, fruits and vegetables, with some meat, fish and dairy products, and small amounts of foods that are high in saturated fats ('bad' fats) and added sugars. Given the fact that there is no single food that can provide all the important nutrients needed by the body, it is especially important for a mom-to-be to eat a wide variety of foods to stay healthy.

So what are these nutrients, what makes them important, and what kinds of food contain these nutrients?

These nutrients can be divided into two classes: macronutrients and micronutrients. As the term suggests, macronutrients are nutritional components of our daily diet that are required in relatively large amount. Examples of macronutrients include protein, carbohydrates and fats. On the contrary, micronutrients are nutrients that your body needs in relatively small amounts, including calcium, folate, zinc, iron and vitamins. However, a lack of these micronutrients in small amounts can lead to serious health problems.

As nutritional needs change with each life stage, food intake during pregnancy, lactation, weaning and toddlerhood are critical to ensure a healthy supply of macro- and micronutrients to the pregnant mother and the developing baby.

The role and functions of macronutrients and micronutrients are summarized in the table below.

Table: Overview of the role and functions of macronutrients and micronutrients

Nutrient Examples of major functions
Macronutrients
Carbohydrate
  • Provides energy2
  • Serves as main fuel for the brain2
Protein
  • Serves as building blocks that make up all the cells in the body
  • Functions as enzymes and hormones that assist in all bodily functions2
Fats
  • Provides energy2
  • Helps the body to absorb fat-soluble vitamins A, D, E and K, and carotenoids (a group of health-promoting plant chemicals)2
  • 'Good fats' such as long-chain polyunsaturated fatty acids (LC-PUFAs) enhance visual development3
Micronutrients
Folate (vitamin B9)
  • Assists in many bodily functions, such as making the body's genetic material (eg, DNA) and new red blood cells4
  • Helps to prevent birth defects, such as defects of the brain and spinal cord (also known as neural tube defects)5,6
Vitamin A
  • Aids in cell growth and differentiation - a process when a cell becomes a part of the eyes, lungs and intestines, or other tissues7
Calcium, vitamin D
  • Help to prevent soft or brittle bones (a condition known as rickets) in infants and children8,9
Iron
  • Helps to maintain healthy brain and nerve function
  • Assists in the production of new red blood cells10
Iodine
  • Helps to maintain healthy brain and nerve function11,12

The summary below features the recommended nutrient intake (RNI) values proposed by the Chinese Nutrition Society (2013) for some macro- and micronutrients needed during critical stages of life.13


Pregnancy

The nutritional status of the mother at conception and during pregnancy plays a major role in the health and well-being of the mother herself and the baby. Below are some nutrients that play an important role during this stage.

Protein

During pregnancy, more protein is needed to maintain the growth of tissues of the foetus (unborn baby) and the mother.2 The RNI for protein is 55, 70 and 85 g/day in early pregnancy, second and third trimester, respectively.13 Low intake of protein by pregnant women could result in an infant who is short and lighter in weight.2 Increasing the protein content of the mother's diet during pregnancy has been shown to significantly improve the birth weight of infants.2 Food sources of protein include meat, poultry, fish, eggs, dairy products, legumes (plants with edible seeds and pods), grains, nuts and seeds.2 One tael of meat, one glass of milk or one medium-sized egg, each gives approximately 7 g of protein, which equals to 1 serving.14

According to the guideline13, extra protein intake is not necessary during early pregnancy. The intake of protein needs to be increased during second and third trimester for the rapid growing fetus. For a pregnant woman with light physical activity, 5-7 servings of meat plus 2 servings of milk per day can contribute to a balanced diet with sufficient protein intake. For vegetarian pregnant mothers, needs of protein can be met by dried beans, tofu / soy products and nuts. However, vegetarian mothers are advised to consult healthcare professionals on their meals plan.

Folate

A woman's need for folate increases during pregnancy due to the demand of the growing foetus.4 It is now well known that a mother's dietary folic acid supplementation around the time of conception can reduce the risk of defects of the brain and spinal cord in newborns.5,6 Folic acid supplementation around the time of conception also prevents other birth defects such as heart defects and oral clefts (characterized by a split or opening in the upper lip).17 A low level of folate in the body is associated with adverse outcomes for mothers (eg, anaemia and nerve malfunction)4 and pregnancy complications (eg, preterm delivery, low birth weight in infants and stunted growth in foetuses).18

Since the body cannot produce folate, it must be obtained from diet or supplementation. Dietary folate, a naturally occurring nutrient, is found in dark green vegetables (eg, choy sum), legumes and beans, fruits (eg, cantaloupe and oranges), livers, peanuts and nuts, and folate-enriched breakfast cereals.19 Folic acid is a synthetic dietary supplement that is available in artificially enriched foods and vitamin preparations. For women of childbearing age (18-49 years), the RNI for folate is 400 μg/day and this increases to 600 μg /day during pregnancy.13 The Family Planning Association of Hong Kong recommends that women who are planning a pregnancy should take a folic acid supplement (400 μg/day), starting before conception and continuing during the first 12 weeks of pregnancy.20

Iron

Iron is an essential nutrient for normal development of the foetus. In addition to being used in the production of red blood cells, iron plays a crucial role in the development of the central nervous system.10 Foetal iron deficiency may negatively affect the intelligence and behavioural development in childhood.10 Iron is also needed by the mother to prevent iron deficiency anaemia in mothers themselves, which is a risk factor for preterm delivery and low birth weight.10

Dietary sources of iron include pork, beef, poultry, fish, eggs, livers, green vegetables (eg, choy sum, bok choi and spinach), dried beans (lentils, red kidney beans and chick peas), nuts and iron-fortified breakfast cereals.19 Some plant-based foods, such as spinach, are good sources of iron, but they naturally contain iron-absorption inhibitors, which make the iron not available for absorption.21 Iron supplementation may be needed to meet the increased demands during the later stages of pregnancy when a mother's needs for iron increases to approximately 1000 mg to support the growth of the foetus and placenta (a temporary organ that feeds the foetus inside its mother's womb), added blood volume and blood loss during childbirth.22 To meet these increased needs, the RNI for iron increases from 20 mg/day in early pregnancy to 24 mg/day and 29 mg/day in the second and third trimesters, respectively.13 However, over-supplementation of iron is not recommended because too much iron can negatively affect absorption of minerals, and cause injury and damage to a variety of tissues and organs.23 1 serving of iron fortified breakfast cereal, six ounces of cooked oysters or two cups of white beans, each gives approximately 18 mg of iron.21

Calcium

During pregnancy, calcium from the mother is transferred to the foetus for the formation of the skeleton (via a process known as skeletal mineralization).24 Most of the foetal calcium accumulation takes place in the later stages of pregnancy, and the absorption of calcium and loss in bone mass in the mother increase to meet this rising demand.25 The increased calcium absorption is related to the mother's calcium intake; therefore, dietary calcium supplementation could potentially prevent temporary bone mass loss associated with childbearing.26 The RNI for calcium is 800 mg/day in early pregnancy and 1000 mg/day in the second and third trimesters.13 Calcium-rich foods include dairy products, tofu set with calcium salt, fortified soy milk, dark green vegetables (choy sum, kale, bok choi, mustard greens and broccoli), sesame seeds and nuts, dried shrimp, small dried fish and canned fish with edible soft bones.19 One glass of milk, three pieces of sardines or 300 g of choy sum, each gives approximately 300 mg calcium.1

A pregnant woman who does not consume adequate amounts of dietary calcium may be at increased risk for preeclampsia (a condition in which the mother develops high blood pressure and protein in the urine), preterm delivery or long-term excessive bone mass loss.25 However, excess calcium intake may cause calcium overload in the blood (hypercalcaemia) and urine (hypercalciuria), which may lead to poor kidney function, build-up of calcium salts in blood vessels and tissues, and formation of kidney stones.25 A mother's calcium intake does not appear to influence foetal bone development when calcium intake is close to recommended levels; bodily processes by which calcium is regulated and bone is formed provide sufficient calcium for foetal growth without the need for increased dietary calcium intake.24

Iodine

Iodine is one of the building blocks of thyroid hormone, which plays a vital role in foetal and postnatal brain development.12 Low levels of thyroid hormone (described as hypothyroidism) during these critical periods can cause impaired mental development and problems in the body's nervous system.12 Adequate iodine nutrition during pregnancy is needed to meet the demands of increased production of thyroid hormones in the mother and foetus. The RNI for iodine during pregnancy is 230 μg/day.13 Dietary sources of iodine include milk and dairy products, saltwater fish and shellfish, eggs, seaweed and iodized salt.27 One gram of seaweed snack, two eggs or 200 g of big eye fish, each gives approximately 35 μg of iodine.1

A serious lack of iodine during pregnancy can cause a birth defect known as 'cretinism', characterized by severely stunted mental growth.28 Iodine supplementation during early pregnancy in moderately iodine deficient mothers was shown to improve the development of the child's nervous system.28 Furthermore, iodine supplementation in severe iodine deficiency mothers was found to reduce rates of foetal death and cretinism.11 It is important not to exceed the recommended levels of iodine as excess iodine intake in mothers may cause goitre (swelling in the neck due to an enlarged thyroid gland) and congenital hypothyroidism (thyroid hormone deficiency at birth).27,29


Lactation

The World Health Organization (WHO) recommends that infants should be exclusively breastfed for the first 6 months of life and continued for up to 2 years of age or beyond along with appropriate complementary feeding.30 Which nutrients are especially required to support the needs during lactation?

Carbohydrate

A mother's need for carbohydrate is increased during lactation; an increased supply of glucose is needed to produce lactose, which is present at 74 g/L of breastmilk.2 The acceptable macronutrient distribution range (AMDR) for total carbohydrate in lactating women is 50-65% of total energy intake.13 Dietary carbohydrate is generally found as starch in corn, tapioca, flour, cereals, pasta, rice, potatoes and crackers.2 Various forms of sugar (eg, white, brown and raw sugars, malt syrup and honey), molasses and corn syrup also contribute to overall carbohydrate intake.2

A low-carbohydrate diet (often aimed at weight loss) in lactating women is not recommended as it may induce ketosis (a condition that reflects dietary imbalance and the potential to make you feel unwell) and reduced milk production.31 In addition, the smell and taste of breast milk could also change, potentially affecting infant intake.31 However, consuming a high-carbohydrate (including sugars and starches) diet may pose long-term health problems, such as chronic heart disease and diabetes.2

Calcium

The heavy demand for calcium placed on the mother during pregnancy continues into lactation where approximately 200-300 mg/day of calcium is lost.32 Lactating women should continue to receive the recommended levels of calcium as the mother's bone mineral continues to dissolve during lactation and the minerals stored in the skeleton can only be replenished in later stages of lactation after breastfeeding has stopped.24 The RNI for calcium in breastfeeding women is 1,000 mg/day.13 Calcium is found in dairy products, tofu, dark green vegetables, canned fish and nuts.19 One glass of milk, three pieces of sardines or 300 g of choy sum, each gives approximately 300 mg of calcium.1

Vitamin A

Vitamin A is essential for the normal growth and development of young infants. During the period after childbirth and early infancy, the baby's vitamin A stores are rapidly increased through breastfeeding; colostrum (first stage of breastmilk) and early breastmilk are remarkably rich in vitamin A.33 The amount of vitamin A in breastmilk is directly related to the mother's dietary intake and therefore supplementation can replenish the vitamin A lost daily in breastmilk. The RNI for vitamin A in breastfeeding women is 1,300 μg retinol activity equivalents (RAE)/day.13 Dietary vitamin A is found in livers, eggs, milk, green leafy vegetables, cherries, tomatoes, pumpkins, carrots and yellow/orange fruits such as oranges, mangos and papaya.19,34 One cup of boiled spinach or one fresh tomato each gives about 1,000 μg RAE.14

Breastfeeding is protective against the risk of developing xerophthalmia, a sign of vitamin A deficiency and a condition that causes extreme dryness of the eye.35 However, long-term intake of high doses of vitamin A can damage the liver.19 Furthermore, infant vitamin A supplementation at a large dose may cause temporary bulging of the fontanelle (the soft spot of the baby's skull).36

Vitamin D

Vitamin D is an essential nutrient required by the growing infant. In addition to maintaining bone health, vitamin D also plays an important role in the functioning of the immune system, cell growth and cardiovascular health.9

Breastmilk from healthy lactating women provides only small amounts of vitamin D.8,9 Breastfeeding without adequate sunlight exposure and vitamin D supplementation can lead to vitamin D deficiency and rickets.9 In addition to causing rickets with serious abnormalities in the skeleton and poor overall growth, low levels of vitamin D in the infant increases the risk of serious lung infections.9 The RNI for infants aged 0-6 months is 10 μg/day (400 IU/day).13 Most of the vitamin D is made in the skin when exposed to sunlight. Lactating women are advised to expose their face and arms to sunlight daily for a few minutes during mid-morning or mid afternoon.1 The main dietary sources of vitamin D include eggs, fortified milk, dairy products or juice, and fatty fish (eg, salmon, sardine and eel).9,19

Docosahexaenoic Acid (DHA)

DHA is one of the omega-3 LC-PUFAs that serves as a major building block for tissues in the brain and eyes, where it plays critical roles in visual and nerve function.37 The rate of brain growth peaks during the later stage of gestation and in early infancy, which results in a high demand for DHA.37 A mother's dietary intake of different types of fatty acids directly influences DHA levels in breastmilk, which in turn affects DHA levels in blood of the breastfed infant.37 Higher LC-PUFA levels in colostrum compared with lower levels have been shown to improve mental development in infants who had been breastfed during their first year of life.38 Furthermore, supplementation with LC-PUFAs in mothers during pregnancy and lactation has been linked to improved vision and mental abilities in infants/children.3,39

The RNI for DHA in lactating women is 200 mg/day.13 Good sources of DHA include oily fish, such as salmon, sardine, golden thread, and pomfret.1 Vegetarians can choose flaxseeds and walnuts, which are rich in alpha-linolenic acid that can be made into DHA in the body to a certain extent.1


Weaning

Weaning refers to the time when complementary feeding begins, typically at the age of 6 months. A variety of solids (with different tastes and textures) and liquids should be introduced to the infant's diet as weaning continues.

Iron

By 4-6 months of age, an infant's iron stores from birth begin to decline.40 Additional iron through diet or supplementation should be provided to meet the RNI of 10 mg/day13 (for infants aged 6-12 months). It is important to adopt healthy feeding practices to prevent iron-deficiency anaemia in the infant, which may present as slow weight gain, pale skin, loss of appetite and irritability.41 Iron-deficiency anaemia can cause long-lasting impairment in mental, motor and behavioural development in infants.42

Iron rich foods could be introduced in a minced/pureed form; these include meats, fish, egg yolk, legumes and vegetables such as spinach and broccoli.41 Rice or wheat cereal fortified with iron is a good source of iron at the beginning of weaning.43 When the infant is able to eat meat or egg yolk and vegetables on a daily basis, the cereal can be gradually replaced with congee.43 A 100 g serving of egg yolk provides 6.5 mg of iron and 100 g of spinach provides 2.9 mg of iron.14 Combining vitamin C-rich fruits and vegetables will enhance iron absorption from non-meat sources (eg, green leafy vegetables and dry beans).43

Zinc

Along with iron, zinc is needed for normal growth, generation of new blood cells and healthy development of the nervous system during infancy.44 Over the first six months following childbirth, there is a progressive sharp drop in the zinc content of breastmilk, resulting in decreased zinc intake in the older infant.45 During weaning, supplementation or zinc-rich complementary foods is important for preventing zinc deficiency, which is linked to anorexia, faltering growth and poor immune function.46 The RNI for zinc in infants aged 7-12 months is 3.5 mg/day.13 Dietary sources of zinc include beef, chicken and zinc-fortified infant cereals.44,46 A 100 g serving of cooked boiled beef contains 5.02 mg of zinc.47

Zinc is generally non-toxic but excessive levels may cause in copper toxicity and a possible link to autism has been suggested.45

Vitamin A

During lactation, infants build up adequate stores of vitamin A in the liver.48 When milk intake declines during weaning, unless adequate vitamin A rich foods are consumed, the infants' vitamin A stores decrease quickly, potentially causing vitamin A deficiency.48 For infants aged 6-12 months, an adequate intake (AI) of 350 μg RAE/day is recommended.13 Dietary vitamin A can be derived from animal (eg, milk, eggs, liver) or plant (eg, dark-green leafy vegetables and deep yellow fruits and vegetables) sources.48 One medium-sized cooked tomato contains 30 μg RAE and one medium-sized cooked carrot contains 392 μg RAE.14

Low consumption or exclusion of dark green leaves, yellow fruits or eggs during weaning has been linked to an increased risk of xerophthalmia.49 In infants aged 6 months or older, correcting vitamin A deficiency reduces the risk of death due to diarrhoea, measles and other infections, and protein-energy malnutrition.33

Vitamin B6

Vitamin B6 plays an important role in normal brain function, particularly when the brain of infants is still immature.50 It can be supplied by breastmilk, but the infants' stores of vitamin B6 can easily become depleted by the age of 4-6 months.51 Appropriate complementary foods, such as enriched and fortified cereals, meats, potatoes, bananas and legumes, should be introduced to maintain adequate vitamin B6 levels in the infant.51 The RNI for vitamin B6 in infants aged 7-12 months is 0.4 mg/day.13 One medium-size banana contains 0.4 mg of vitamin B6.52

Vitamin B6 deficiency has long been known to cause epilepsy in infants.50 Furthermore, it is associated with poor infant growth.54 Excess consumption of B6 (through fortified foods and/or formula) by weaned infants may cause obesity in adult life.53

Iodine

Iodine deficiency during infancy can cause irreversible impairment in the development of the nervous system, and even death.12,54 Breastmilk provides adequate iodine to infants, but during the weaning period infants are particularly vulnerable to developing iodine deficiency for several reasons: the requirements for iodine and thyroid hormone per kilogram bodyweight are highest during infancy; salt (iodized or not) and cow's milk (a major source of dietary iodine) are not recommended during the first year of life.12 Therefore, to prevent iodine deficiency and maintain normal thyroid function, weaning infants need additional dietary and/or supplemental sources of iodine. An AI of 115 μg/day of iodine is recommended for infants aged 7-12 months.13 Fortified infant foods and milk formula could potentially increase iodine intakes in weaning infants.54 Seaweed is the best source of iodine and eating a small amount is enough; other good sources of iodine include seawater fish and shrimp.43


Toddlerhood

The transition from infancy to toddlerhood occurs at about 1 year of age and is accompanied by increased demands for energy and nutrients. Toddlers have teeth and improved motor skills to be able to consume a more varied diet. Intake of the following nutrients is important for their growth.

Fats

Toddlers need high amounts of energy from fats to support their growth and rapid brain development.55 Fats and cholesterol should not be restricted in children younger than 2 years; however, beyond 2 years of age, bad fats such as trans-fatty acids and saturated fats should be avoided in favour of good fats - PUFAs.55 In children of 1-3 years old, the recommended AI for fat is 35% of total daily energy.13 Food sources that contribute to fats intake are butter, margarine, vegetable oils, visible fats on meat and poultry products, whole milk, egg yolks, nuts and baked goods, such as cookies and cakes.2 In particular, vegetable oils such as soybean and flaxseed oils, and fatty fish are good sources of PUFAs (including DHA).2

Fats restriction may hinder the growth and deprive toddlers of essential nutrients such as fat-soluble vitamins.55 Deficiencies in LC-PUFAs may affect the maturation of the central nervous system.55

Protein

Adequate intake of protein is required by the toddler to maintain the rapid growth and development that continues during this stage. For children aged 1-2 years, the RNI for protein is 25 g/day and for 3-year olds, it increases to 30 g/day.13 Food sources of protein include meat, poultry, fish, eggs, milk, cheese, yogurt, legumes, grains, nuts and seeds.2

Protein deficiency can have long-term negative impacts on brain function in infants and young children.2 Diets low in protein and energy often result in a deficit in weight-for-height (wasting) and height-for-age (stunting).2 These deficits can be corrected with a high-protein diet and an adequate energy intake to allow catch-up growth.2 Although protein is essential for proper body functioning, consuming too much protein can lead to harmful effects such as nausea, diarrhoea, loss of calcium, dehydration and kidney problems.56

Calcium

Calcium is important for bone growth, tooth development and muscle contraction, and may help maintain normal blood pressure and body fats.55 Bone formation in childhood appears to be a cumulative process and this was demonstrated in a study where cumulative calcium intake in the first 5 years of life increased bone mass in later childhood; calcium intake during the second year of life correlated best with bone mineral content at 5 years.57 A very low calcium intake can results in the development of rickets in infants and children.58

The RNI for calcium in children aged 1-3 years is 600 mg/day.13 Vitamin D enhances calcium absorption.59 Milk is the primary source of calcium for toddlers. Other calcium-rich foods include cheese, yogurt, tofu, spinach, broccoli, orange, sweet potatoes and sardines or salmon with bones.19,58 One glass (240 mL) of 2% low fat milk contains 285 mg of calcium and one slice of low fat cheese contains 116 mg of calcium.60

Vitamin C

Vitamin C is an antioxidant and is involved in the body's production of collagen (a type of protein that makes up the main component of connective tissues) and neurotransmitters (brain chemicals that relay information throughout our brain and body).61 It also enhances the body's absorption of iron.61 The RNI for vitamin C in children aged 1-3 years is 40 mg/day.13

Vitamin C deficiency results in scurvy, which manifests as tooth loss, joint pain, bone and connective tissue disorders, and poor wound healing.61 Since human cannot produce vitamin C in the body, it has to be obtained from the diet. Vitamin C is found in fresh vegetables and fruits (eg, oranges, kiwi fruits and strawberries).19

Zinc

Zinc is required for many bodily functions, such as reproduction, growth and defence against free radicals.61 In addition to supporting the growth and development of children, vitamin C and zinc play complementary roles in supporting immune functions and combating various infections.61 The RNI for zinc in children aged 1-3 years is 4 mg/day.

Zinc deficiency increases the risk and severity of infections, restricts physical growth and delays wound healing.61 The risk of stunting is greatest during the period of rapid body growth until the age of 3 years.61 Zinc supplementation can restore normal growth and weight gain in previously stunted or underweight children.62 Dietary sources of zinc include meat, fish, nuts, seeds, legumes and wholegrain cereal.61


Summary

Maintaining the right nutrition throughout the periods of pregnancy, lactation, weaning and toddlerhood is critical to ensure the best possible health and developmental outcomes for both the mother and the baby. While there is a wide variety of foods and supplements available today to supply all the essential macro- and micronutrients, it is up to the mother/mother-to-be to make the right food choices to meet the changing nutritional needs and demands during these important stages of life.

References

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