8. Discussion

The results of these studies on growth of children on macrobiotic diets have provided the following answers to our research questions:

1. Timing of growth faltering in children fed macrobiotic diets: A small but significant intrauterine growth retardation was indicated by a lower birth weight of macrobiotic children. Growth velocities in height and weight were most depressed between 8 and 14 months of age. Between 14 and 18 months of age, growth stabilized parallel to the 10th centile of the Dutch references, after which some, but incomplete catch-up growth was observed for weight and arm circumference. No catch-up growth was observed for height.

2. Nutritional factors associated with deviations in growth in children on macrobiotic diets: Low birth weight was associated with a low frequency of consumption of fish and dairy products by the mother. SDS of weight, height and arm circumference were significantly higher in children from families consuming dairy products regularly compared to children from families which rarely used dairy products. The increase in weight and arm circumference between 4 and 18 months of age was associated with both the energy intake and protein content of the diet. Growth in length was only associated with the protein content of the diet.

3. Effect of modification of the macrobiotic diet on growth: Catch-up growth in height and weight occurred after increased consumption of fish and dairy products. Our findings demonstrate that, provided unfavourable nutritional circumstances change, catch-up growth in height is still possible even at the age of 8 years, even though the original growth channel may not be attained.

Our data demonstrate that the observed linear growth retardation in children on macrobiotic diets is caused by nutritional deficiencies alone. By using a matched control group in the mixed-longitudinal study, confounding factors as sex, parity, socio-economic level and region of residence were excluded. The educational level of the parents was high, and 92% of macrobiotic infants grew up in a two-parent family (control group: 100%). No indications of any other adverse circumstances such as prevalence of infectious diseases were observed.

Fig. 3. Growth in weight and height of three macrobiotic siblings in the Netherlands before and after the modification of the macrobiotic diet by introducing dairy products and fatty fish (shown as 'A').

Figure (3a)

Figure (3b)

Figure (3c)

The associations observed in this study of linear growth with consumption of dairy products and fish suggest the importance of protein, and particularly animal protein in the diet. It has been suggested that height is affected most by protein deficiency (Ashworth & Millward, 1986; Malcolm, 1978) whereas weight is more sensitive to a low energy intake (Malcolm, 1978; Waterlow, 1978). Our data seem to support this hypothesis. However, although we can analyse the separate effects of various nutrients in a regression analysis, in real life we cannot disentangle the influence of the protein content of dairy products and fish from the influence of the extra energy, calcium, zinc, or changing bioavailability of iron and other nutrients, which are supplied simultaneously with the consumption of these products. Furthermore, a low utilization of the protein in the macrobiotic diet, due to its low energy and high fibre content, might have played a role in limiting linear growth. Finally, our data also support the notion that linear growth retardation is related to inadequate weight gain (Waterlow, 1991): growth velocity in height was lower for the wasted macrobiotic infants compared to the non-wasted macrobiotic infants in the mixed-longitudinal study. Thus, this suggests that sufficient energy is also needed for normal linear growth.

Catch-up growth is a self-correcting response which occurs as soon as an adequate diet is provided (Ashworth & Millward, 1986). Thus, catch-up growth may serve as a retrospective diagnostic tool (Bergmann & Bergmann, 1978). The catch-up growth in height in children whose diet has been extended with dairy products and fish suggests that before modification the diet was nutritionally inadequate. As discussed above, we cannot tell which nutrients, or combinations of nutrients and absorption enhancing factors were responsible for the linear catch-up growth after extension of the diet with dairy products and fish. The influences of separate nutrients can only be studied by intervention. The fact that catch-up growth in height even occurred in macrobiotic children of 8 years of age indicates that also for older children the macrobiotic diet continues to be nutritionally inadequate.

The importance of dairy products is also illustrated by comparison of anthropometric data of children on facto-vegetarian diets and children on macrobiotic diets. In macrobiotic children, whose diet lacks dairy products, stunting is combined with a normal weight for height, whereas children on facto-vegetarian diets, who receive dairy products, show some degree of wasting but virtually no stunting (Van Staveren et al., 1985; Dwyer et al., 1980).