Replacing cow’s milk with plant-based drinks: consequences for nutrient intake of young children on a balanced diet in Germany | Journal of Health, Population and Nutrition

Overall

In wealthy countries, the trend towards reducing animal-based foods in favor of plant-based alternatives has led to a need to review established dietary guidelines and to determine whether the balanced nutrient intake may be significantly compromised by these changes. Using the OMD as a model for feeding of young children, the specific scenarios of replacing liquid milk with plant-based drinks showed that:

1. 1.

   The replacement of milk leads to a small reduction of less than 10% of energy intake, but the intake of important micronutrients from milk is significantly reduced and may become critically low.

2. 2.

   The consequences for nutrient intake depend less on the kind of plant used as substitute and much more on the nutrient fortification by the manufacturers.

Products and nutrients

Plant-based drinks are increasingly discussed in the literature, with the focus mostly on the product level, e.g., on differences to the composition of milk or differences in composition between drinks depending on the base plant [11,12,13]; whereas papers discussing the impact of plant-based drinks on the diets of children [14] are rare. Milk is a key source of iodine in many countries [15], but several studies have shown that most plant-based milk alternative drinks on the market are not fortified with iodine [15,16,17]. As these unfortified drinks have a low concentration of iodine, consumers of unfortified milk alternatives may be at risk for a lower iodine intake and status than cow’s milk consumers [18].

The drinks examined here reflect the range of products marketed in Germany [3] quite well. A special feature of our survey is the additional evaluation of products that are offered especially for young children. This proved to be worthwhile because of the fundamental differences in the composition of these children’s products and the products for general consumption.

The soy-based formula belongs to the category of Foods for Special Medical Purposes (FSMP) defined by EU law and complies with the EU nutrient regulations for infant and follow-up formula [19]. The growing-up soy-based product is closer to milk than the formula, but the European Food Safety Authority (EFSA) stated that special young child formula cannot be considered as a necessity to satisfy the nutritional requirements of young children. EFSA considers fortified young-child formula, as one of several means to increase n-3 PUFA, iron, vitamin D and iodine intakes in infants and young children living in Europe with inadequate or at risk of inadequate status of these nutrients [20].

Depending on the base plant there are well-known differences in protein: in soy, protein content and biological value are higher than in cereals and nuts. In a balanced mixed diet for young children with a moderate proportion of animal products, as in the OMD, the protein quality of the milk substitute is generally not critical due to the high protein supply. However, soy-based drinks could be advantageous over other plants groups if protein intake is scarce, for example in restrictive diets for young children.

On the other hand, soy is not uncontroversial in infant and young-child nutrition. Currently, in the EU, most infant and follow-up formula are based on cow’s milk, isolated soy protein is permitted as well (with a slightly higher protein content to compensate for the lower protein quality). In the view of pediatric nutritional medicine, the use of soy products for healthy infants should be limited to a few medical indications (galacatosemia, congenital lactose intolerance) or explicit parental preferences (desire for vegan nutrition or other ideological reasons) [21]. In these cases, medical supervision and appropriate supplementation are recommended.

The dietary assessment of plant-based drinks must also take into account the bioavailability of the nutrients, which may be lower than in milk, e.g., in the case of calcium, depending on the calcium salt and the food matrix [22, 23]. The fortification of the examined drinks for general consumption largely mimics the contents in milk, whilst the products intended for infants and young children additionally include the critical nutrients iron and iodine.

The non-fortified drinks in our study which reflect about 80% of the products on the market in Germany are often so-called “Organic products”. For this product type, fortification is made more difficult by EU Regulation 2018/848 [24], originally with the aim of protecting these products from (undesirable) additives or impurities. However, parents in Germany seem to perceive the label “organic” as associated with health benefits for their children [25]. It may be a challenge to convincingly inform parents that organic products may also be disadvantageous for their children’s nutrient supply in individual cases.

Consequences for nutrient supply

Here, the replacement of milk with plant-based drinks was investigated with a focus on the consequences for a guideline diet, which is designed to be nutritionally balanced and safe. The model of the OMD facilitated such an approach, as this concept is based on a detailed 7-day menu and thus can show the specific consequences of replacing individual foods for the resulting nutrient intake. The scenarios were designed to be realistic and low-threshold, by only replacing the fluid milk in the menu 1:1 with plant-based drinks; the preparation of the meals otherwise remained unchanged. As the solid dairy products (yoghurt, cheese) were retained, which make up around a third of the OMD dairy group in terms of consumption and around half in terms of energy intake, at first glance one would expect rather minor effects on nutrient intake.

Indeed, the protein quantity and quality of the OMD is hardly affected by replacing milk with plant-based drinks. With restrictive dietary patterns, however, plant-based drinks with low protein quality could impair the protein supply in periods with high protein requirements due to intensive growth.

In case of micronutrients, the scenarios show distinct negative consequences for intake when using plant-based drinks without fortification. This applies in particular to calcium and vitamin B12, as these two micronutrients just reach the German reference intakes in the original OMD [7]. The deficiencies with plant-based drinks are difficult to replenish with other natural common foods. With drinks, fortified corresponding to milk, the safety of the nutrient intake of the OMD for young children is maintained.

A special issue is the critical nutrient iodine in children. As in other countries without universal salt-iodization policy, the supply in Germany is inadequately low [26] and even trending downwards [27,28,29]. In addition to iodized table salt, the main source of iodine for children is milk. Many young children do not yet participate fully in the family diet and cannot yet benefit fully from the use of iodized salt. Iodine fortification of plant-based drinks would be beneficial for iodine supply of young children. Thus, manufacturers of plant-based alternatives (such as plant-based milk alternatives) should be encouraged to fortify products to be equivalent to animal-based products (for example, cows’ milk).

Unlike iodine, cow’s milk is an insignificant source of iron. With the original OMD, iron intake and sufficient bioavailability is ensured from the mixture of animal-based and plant-based foods. Accordingly, our scenarios show that the iron intake in the OMD is not compromised by the replacement of milk with plant-based drinks.

However, if plant-based drinks are designed with a significantly higher iron content than milk, then the iron intake increases above the OMD amount, however, the selection of suitable iron compounds is a prerequisite for sufficient bioavailability. High iron intake in young children may be of interest in certain individual cases (according to medical indication).

In the actual diet of young children in Germany, milk consumption has been reported to be close to the recommendation, and calcium intake almost in line with the nutrient reference [30, 31]. The scenarios of this paper therefore appear to be transferrable to the actual diet of young children in Germany.

Child-friendly compromise of healthy and sustainable diet

In principle, the OMD is a ‘modern’ plant-based mixed diet, based on three simple rules for food selection which are to consume beverages and plant-based foods generously, animal-based foods moderately and high-fat, high-sugar foods sparingly [7]. If such a diet is to achieve a further gain for the environment through modifications, then this possible gain should be reasonably quantifiable. At present, reliable sustainability data for “plant-based substitutes for animal foods” are not generally available [32].

The safety of established guideline diets is based not only on science but also on observations of children thriving on these diets. With the increasing introduction of newly designed substitute products for animal foods, these safety aspects would have to be adequately demonstrated for the individual new product groups [33].

Strengths and limitations

Among the strengths of this analysis is the exact data of consumption of individual foods in the OMD 7-day menu, even with a specification of fluid milk (within the dairy group) that enables realistic exchange scenarios.

The use of a comprehensive nutrient data base enabled calculation of total daily nutrient intake and thus of consequences of milk exchange for dietary adequacy. Moreover, the background of a representative recent market survey in Germany made it easier to correctly classify the products that were selected for our calculations.

A limitation is that nutrient content of the selected products could not be confirmed by chemical analysis but had to be taken from the product labels.

Conclusion

The fact that even a small reduction in nutrient-rich animal-based foods, such as replacing liquid milk by insufficient alternatives in a balanced children’s diet, has distinct effects on the micronutrient intake of young children poses major challenges for the proper information of parents. The assessment of even small interventions in a balanced diet need an expert view of advisors.