Introduction of Solid Foods - Part 2 Consequences of introducing solid foods too early If foods in addition to milk are offered before the infant is developmentally ready (e.g. while the extrusion reflex is still strong) the mother may feel that the infant is rejecting the food rather than objecting to the injection of the spoon (a hard object) into the mouth. This can lead to an adversarial relationship between the mother and the child. During this same period young infants who have not developed control over the motions of the head or the ability to sit upright with support do not have the ability to signal either hunger or satiety by moving the head either towards or away from the food offered. In a study of the acceptance of solid foods by infants, Beal 3demonstrated that introducing solid foods before the infant could handle them (e.g. two months of age) did not lower the age at which the infant accepted the food. It merely increased the period during which the feeding situation was frustrating and unpleasant for both the mother and child. Since establishing habits of eating in moderation is a goal of early feeding practices, any attempt to force a child to eat beyond satiety is undesirable. In addition, infants should be allowed to discontinue eating at the earliest sign of willingness to quit. An excessive consumption of high carbohydrate weaning foods of low caloric density, such as fruit and vegetables, may lead to a significant decrease in intake of total energy and some essential nutrients if these foods replace milk. There will also be a decline in the percentage of dietary energy provided by fat if these foods replace breast milk or formula in which as much as 50% of the calories are provided by fat. Since fatty acids are essential in the development of the central nervous system in infancy and early childhood, and since there is no evidence of benefit from the restriction of dietary fat in infancy on the risk of CHD later in life, any attempt to restrict fat intake in early infancy is considered inappropriate. 4 If, on the other hand, the foods introduced too early in life supplement the milk diet, the result may be an elevated caloric intake with a tendency towards a rapid weight gain in excess of recommended levels. There is also the possibility that at this age, a diet with a significant fiber intake may result in a diet of lower nutrient density which compromises nutritional status. For children with a genetic predisposition to food sensitivities or allergies, the more foods that are introduced before the gastrointestinal tract has matured, the greater is the possibility that the infant will develop food allergy or sensitivity. For these infants, sources of common dietary allergens found in cow's milk, nuts, eggs, soy and wheat proteins should be avoided as long as feasible. The infants' acceptance or rejection of certain flavors appears to change as the central and/ or peripheral mechanisms underlying certain taste perceptions mature. For instance, infants who are indifferent to or reject salt in the neonatal period, accept it at four months of age. 5This points to the wisdom of offering a previously rejected food again at a later time when the gustatory or olfactory responses may have been modified to permit acceptance of the food. In fact, research on older children suggests that a food may not be accepted until it has been offered as many as ten times. 6The rationale for not adding food before the recommended age may be extended if one considers the fact that increasing the variety of foods offered entails more work for the parent, increases the potential for food allergies and food-borne diseases if food preparation and storage are less than adequate, and allows parents to modify the flavor of food by the unnecessary addition of salt and sugar to satisfy their own adult taste preferences. There is also an increased risk of botulism by feeding the young infant honey, or methemoglobemia associated with feeding foods of high nitrate content from feeding in early infancy. Consequences of failure to start non-milk feedings The most serious effects of withholding solid foods for longer than six months are a diminished growth rate as well as feeding aversion. This is particularly true of the breast-fed infant if the breast milk volume does not increase to meet the infant's increasing needs for energy and certain nutrients. For a six month old infant, solid foods usually provide about 20% of total energy intake while at 10 months they account for half the caloric intake and contributes significantly to the intake of other nutrients. Another consequence of much delayed introduction of non - milk feeding is aversion to foods that require chewing. Iron deficiency, may manifest by four to six months of age, due to failure to add iron - dense solid foods. This is more important for the breast fed infant who may not have iron-enriched cereals at this crucial time than it is for formula fed infants, if the formula is iron - enriched. With the trend toward almost universal use of iron-fortified formula for non-breast-fed infants, the importance of solid foods in preventing iron deficiency is less evident. Iron deficiency is a reflection of a rapid rate of growth which calls for more iron to meet the needs of an expanding blood volume and an increase in muscle mass. Under these circumstances, even when solid foods are introduced, if the dietary iron comes primarily from bread and cereal products of relatively low iron content and often of low bioavailability (2 to 6%), iron deficiency may develop. This is especially true if the diet is also low in meat, fish, poultry or citrus fruits that enhance bioavailability. Conclusions Current knowledge of the nutritional needs of infants and their physiological and physical readiness to accept and handle foods other than breast milk and formula supports the almost universal recommendation that the milk diet of infants be supplemented at four to six months of age. This practice is important if we are to capitalize on the infant's ability to handle other foods, to prevent the development of subclinical, or clinically observable nutrient deficiencies and any metabolic or functional consequences of these, to forestall growth retardation or impaired mental or motor development, and to ex-pose the infant to a progression of flavors and textures to enhance the acceptance of a varied diet. It is well established that human infants are physiologically adaptable and able to survive on a wide range of dietary patterns. We do however have substantial evidence to identify the feeding patterns associated with desirable developmental milestones, opti-mal growth and long term health. There is consensus that infants and young children should be encouraged to consume a wide variety of foods in moderate amounts. Food choices should not be restricted because of the caloric, fat or sugar content of any one food, it is the nutritional profile of the total diet that is of prime importance. References
In Brief...
A balanced diet, as described in both Canada's Food Guide to Healthy Eating and the US Food Guide Pyramid, includes servings from the grain products, vegetables and fruit, milk products and meat and alternatives food groups. Anecdotally, children may have the most difficulty satisfying the suggestion for 5-10 vegetable and fruit servings per day. For pre-schoolers and school-age children, suggestion for the lower end of the range is usual, with a gradual transition from one half to full adult-size food portions. Thus a minimum of 5 servings, each of 1/4 - 1/2 cup of fruit, vegetables or their juices, 1/2 to 1 medium-size fresh vegetable or fruit, or 1/2 to 1 cup of salad is advocated and variety is promoted. With the directive to choose dark green and orange vegetables and orange fruit more often, the childhood favourites of apple juice and potatoes will not, alone, satisfy the recommendations. In Canada, there is little recent data on what children are eating or what supplements they are receiving. The last population-based study of the diet and nutritional status of Canadians, the 1970-72 Nutrition Canada survey, suggested that in the paediatric age groups there was inadequate or less than adequate dietary iron, calcium, vitamin D; and, in adolescents, vitamin A, and biochemical evidence of suboptimal iron and folate status. Overall, the diet of aboriginal children was less adequate than that of child in the general population. The children of the Nutrition Canada survey are the parents of today and there is no comprehensive way of knowing if the same issues persist. However, geographically discrete studies in Canada provide some indication. Recent data from parental 24-hour dietary recalls for 306 pre-school children (4.7 + 0.4 years of age) living in economically - disadvantaged urban communities in Ontario suggest that most did not meet Canada's Food Guide recommendations for the number of servings of milk products (mean of 1.9 servings vs. the 2 - 3 recommended) or servings of fruit and vegetables (mean of 2 and 1.4, respectively vs. 5 in total). 1Nevertheless, mean and median intakes of vitamin A, vitamin C and folate exceeded Canadian recommended intakes (RNI). 2The 10th percentile of intakes fell below recommendations for vitamin A, calcium, iron, zinc and folate. A preliminary report on the iron and folate status of 189 infants and toddlers (2 - 29 months) from Ottawa, also indicated that median intakes of most nutrients exceeded the RNIs. 3Iron was an exception, with 34% of the sample consuming less than recommended levels. Red blood cell folate levels were generally good, with 5% in the depletion range at the outset and all values in the normal range 6 months after entry into child care. Haematocrit values, however, suggested anaemia in about 21% of infants at both entry and 6 month periods. The incidence of anaemia was independent of the incidence of illness or use of antibiotics. Iron status is also a concern for aboriginal children 4, though non-nutritional causes should be considered. 5 School-age children, 7 - 9 years of age, from low income Ontario families (n = 150) had median dietary intakes of calcium and vitamin A which fell below RNIs of 700 mg and 700 RE, respectively. 6Although self-reported 24 hour recalls may not be fully representative of true calcium intake, 7-day food records from 182, 5 - 18 year olds in Quebec also found calcium, of all nutrients, to fall most frequently below recommendations. 7These studies raise concern given that childhood and adolescence is a critical period for the accumulation of bone mass, adequate calcium intakes at this time will help to maximize mineral retention. There are few studies of zinc status in Canadian children. The studies of Smit-Vanderkooy and Gibson 8,9, indicated suboptimal zinc status in a small group of pre-school boys with low height percentiles, with a positive growth response to zinc supplements. Median zinc intakes below the U.S. RDA were reported for 3 - 5 year olds in the NHANES III. 10Based on low dietary intakes, it has been hypothesized that zinc is a public health problem for children and women. 11 In summary, for a segment of Canadian children, it appears that food group servings and corresponding nutrient intakes may not meet current recommendations. The situation described for Canada is likely true of some other industrialized countries. In the United States, 3 day food records from 3307 children and adolescents, age 2 - 19 years, suggested that mean dietary intakes were below minimum recommendations for all food groups except dairy, and even then only about one third met national recommendations. 12 Although traditional health care practitioners have not emphasized vitamin - mineral supplementation, it would seem that parents are not convinced. Data from Ontario communities suggest that 35 - 72% of children receive vitamin - mineral supplements on a regular basis. Those children at nutritional risk due to poverty, are, unfortunately, less likely than their affluent counterparts to receive supplements. Interestingly, many commercially available vitamin-mineral supplements do not appear to be tailored to children's needs. Of over three dozen children's vitamin / mineral pills listed in the Canadian Compendium of Non-prescription Products (1996) virtually all had performed vitamin A (more than half at 5,000 IU per tablet), 400 IU of Vitamin D, a spectrum of B vitamins and 50 mg or more of vitamin C. While these sup-plements may increase biochemical levels of the specific vitamins, there is no evidence of nutritional benefit, barring subpopulations with increased needs (e.g. vitamin C for adolescent smokers or vitamin D for children with limited exposure to UV light and hence low endogenous vitamin D formation). In Brief...
Other nutrients are not always present in the supplements. Only about half of the commercial children's supplements contain iron, a small percentage contains folate and, less frequent is the addition of calcium (about 25%) or zinc (about 5%). Nevertheless, mineral supplementation should be approached with caution. Normal physiological adaptation to mineral intakes mean that even when diets are suboptimal, responses to mineral supplements may be variable. Moreover, with mineral supplements there is a risk of mineral-mineral interactions, such as calcium inhibition of iron absorption, and potential toxicity. On the flip side of the coin of vitamin supplement need is excess. In a 1985 report in the Canadian Medical Association Journal, Issenman reported a 3% incidence of overdose in Southern Ontario families using multi-vitamin supplements; the risk of overdose rising with the number of preparations given. 13The potential for toxicity with high intakes of iron, fat-soluble vitamins and trace elements is well established. In addition to accidental poisoning, adverse effects have been associated with megavitamin therapies. In megadose (intakes exceeding 10x dietary recommendations) even water-soluble niacinamide and pyridoxine have been associated with adverse clinical symptoms. The pharmacological use of vitamin-mineral supplements to treat disorders which are not specifically associated with malabsorption or disordered metabolism of that nutrient is currently unfounded in children. Megavitamins have, over time, been promoted for treating behavioural problems, reducing the incidence of the common cold or enhancing IQ. In each case, effectiveness has not been substantially disproved by rigorous clinical trials. Links between antioxidant vitamins and disease prevention (e.g. asthma) in adults are equivocal, and have not extended to paediatric populations. In summary, there are no compelling data to support routine vitamin-mineral supplementation of children at this time. Given the widespread practice of supplementation, however, manufacturers should be encouraged to formulate products which complement the needs of children and do not result in combined daily nutrient intakes from foods and supplements which greatly exceed recommended intakes. References:
J. Stacey - Managing Editor Resigns It is with sadness that I announce the departure of Jim Stacey, the Managing Editor of In-Touch. In the 18 years that Jim has been a part of INI, he has contributed a tremendous effort in making this newsletter what it is today. David L. Yeung Opinions expressed In-Touch are those of the authors and do not necessarily reflect the views of the INI, HINS or the H.J. Heinz Company.
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