Types of infant milk and ingredients

No. It is impossible to recreate breastmilk. Breastmilk is not only nutritionally uniquely suited to the human infant; it also contains hundreds of unique components and living cells to protect infants from infection and to aid development. These components cannot be made in a laboratory. All infant formula are a similar nutritional composition to comply with EU compositional requirements and they are all nutritionally adequate for infants. If a substance was found that was definitely beneficial for infant health that could be added to infant formula, it would be in all products by law.

Breastmilk is a unique living substance and it is impossible for any manufacturer to recreate it. Breastmilk is a complex fluid that contains all the nutrients needed by an infant, in forms that are easily absorbed, and contains a range of protective substances tailored to each infant and the environment he or she lives in. Breastmilk contains: substances such as lactoferrin, a protein component that helps babies absorb nutrients and which binds iron in the gut so that pathogenic bacteria are inhibited; immunoglobulins and macrophages which protect the infant from infections; specific fatty acids which promote development; growth factors, anti-viral factors, anti-bacterial substances and living white blood cells. It is estimated that there are more than 100 substances present in breastmilk that are not present in artificial infant milks. In addition, the milk feed of each mother changes over time, both within the feed and between feeds, to provide the fluid and nutrients the baby needs. The protective effect of breastfeeding for infants and human populations is fully accepted by all scientific agencies and health departments worldwide.

Just because an ingredient can be isolated from breastmilk and recreated in a laboratory does not mean that that ingredient will have the same benefits, or properties, when put into infant formula. Manufacturers often make claims for ingredients that are similar to those isolated from breastmilk, but frequently these are found to have no benefit, and may potentially be a burden to a young infant’s metabolic system.

The European Food Safety Authority Scientific opinion on the essential composition of infant and follow-on formulae(EFSA, 2014) made the following important statement:

“Nutrients and other substances should be added to formulae for infants only in amounts that serve a nutritional or other benefit. The addition in amounts higher than those serving a benefit, or the inclusion of unnecessary substances in formulae puts a burden on the infant’s metabolism and/or physiological functions as substances which are not used or stored have to be excreted.”

The table below shows the composition of breastmilk and infant formula. The data for infant formula is taken from an average of the three major UK brands of cows’ milk based infant formula. Giving one composition for breastmilk is however not easy as breastmilk is a dynamic, living substance whose composition changes over time and during feeds and differs between mothers and populations. Maternal dietary intake, particularly fatty acids, and some micronutrients, including fat soluble vitamins, vitamin B1, and vitamin C, are related to their content in breastmilk. This has led to questions being raised about the nutritional adequacy of milk from vegan and vegetarian mothers who may not be getting enough of some nutrients typically found in greater quantities in animal based foods, from their diet. A recent systematic review has shown that non-vegetarian, vegetarian and vegan mothers produce breast milk of comparable nutritional value for their infants, provided that the appropriate supplementation for breastfeeding mother’s nutritional requirements is provided (Karcz & Królak-Olejnik, 2020).

The compositional data for breastmilk shown here is the average composition of mature breastmilk from a number of sources. Breastmilk contains a wide variety of bioactive substances and protective factors not found in infant formula and this data reflects only the nutrients found in breastmilk and infant formula.

Direct comparisons between the nutrients in breastmilk and infant formula are however of limited value because breastmilk contains substances like lactoferrin that facilitate the absorption of nutrients, making them significantly more bioavailable. In addition, some nutrients may be in different forms in breastmilk and infant formula. The amounts required in infant formula by law allows for these differences in absorption and therefore the greater amounts of some nutrients in infant formula does not infer any superiority, but simply reflects how much more of an added nutrient is needed for the same physiological benefit as that found in breastmilk.

Average for first infant milks: taken from an average of Aptamil 1 First Infant Milk, Cow & Gate 1 First Infant Milk and SMA Pro First Infant Milk. 

* Vitamin D in breastmilk varies considerably and there is little consistency between results from different studies.

Data sources:

Mature breastmilk composition: Finglas et al (2015) except for:

1 Specker et al (1987)

2 Prentice et al (2016)

3 Institute of Medicine (2001)

4 Henjum et al (2020)

5 Spittle (2016)

6 Mullee et al (2012)

7 Holmes-McNary et al (1996)

8 Agostoni et al (2000)

9 Carver (2003)

10 Pereira et al (1990)

11 Mitchell et al (1991).

References

 Agostoni C, Carratù B, Boniglia C, et al (2000). Free amino acid content in standard infant formulas: comparison with human milk. Journal of the American College of Nutrition, 19 (4), pp434-438.

Carver J (2003). Advances in nutritional modifications of infant formulas. American Journal of Clinical Nutrition, 77 (6), pp1550-1554S.

Finglas PM, Rose MA, Pinchen HM, et al. (2015) McCance and Widdowson’s The Composition of Foods, Seventh summary edition. Cambridge: Royal Society of Chemistry.

Henjum, S., Manger, M., Hampel, D. et al. Vitamin B12 concentrations in milk from Norwegian women during the six first months of lactation. (2020) Eur J Clin Nutr 74, pp749–756. https://doi.org/10.1038/s41430-020-0567-x

Holmes-McNary M, Cheng W, Mar M, et al (1996). Choline and choline esters in human and rat milk and in infant formulas. American Journal of Clinical Nutrition, 64, pp572-576.

Institute of Medicine (2001). Dietary Reference Intakes for Vitamin A, Vitamin K,

Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel,

Silicon, Vanadium, and Zinc. Washington, DC: The National Academies Press.

https://doi.org/10.17226/10026.

Karcz K and Królak-Olejnik B (2020) Vegan or vegetarian diet and breast milk composition – a systematic review. Critical Reviews in Food Science and Nutrition,

DOI: 10.1080/10408398.2020.1753650

Mitchell M, Snyder E (1991). Dietary carnitine effects on carnitine concentrations in urine and milk in lactating women. American Journal of Clinical Nutrition, 54 (5), pp814-820.

Mullee A, Brown T, Collings R, Harvey L, Hooper L and Fairweather-Tait S, (2012) Literature search and review related to specific preparatory work in the establishment of Dietary Reference Values. Preparation of an evidence report identifying health outcomes upon which Dietary Reference Values could potentially be based for chromium, manganese and molybdenum (CT/EFSA/NDA/2010/03). Scientific Report submitted to EFSA, 171 pp

Pereira GR, Baker L, Egler J, et al (1990). Serum myoinositol concentrations in premature infants fed human milk, formula for infants, and parenteral nutrition. American Journal of Clinical Nutrition, 51 (4), 589-55.

Prentice P, Ong K, Schoemaker M, van Tol E, Vervoort J, Hughes I, Acerini C, Dunger D (2016) Breast Milk Nutrient Content and Infancy Growth. Acta Paediatrica 105 p641-647

Specker BL, Wey HE, Miller D (1987). Differences in fatty acid composition of human milk in vegetarian and nonvegetarian women: long-term effect of diet. Journal of Pediatric Gastroenterology and Nutrition, 6 (5), 764-768.

Spittle B (2016) Fluoride in Human Breastmilk. Fluoride.49, (4), 2, p471. Last accessed 24/11/2020 file:///C:/Users/User/Downloads/FJ2016_v49_n4Pt2_p471_sfs10%20(1).pdf

Whilst the majority of infant formula in the UK are based on the protein from cows’ milk, unmodified cows’ milk is not suitable as the main milk drink for infants in the first year of life. The immature kidneys of infants are not able to manage the concentration of solutes in whole cows’ milk and the use of infant formula (pre 1970’s) based on unmodified cows’ milk is understood to have been responsible for some infants suffering from severe and even fatal hypernatraemia, hypocalcaemic tetany and convulsions. Legislation now ensures that all infant formula available in the UK contain safe levels of protein and minerals.

In addition, the iron in cows’ milk is poorly absorbed because it is complexed with ligands, principally phosphate. Introduction of cows’ milk to infants aged 6 months has also been associated with small losses of blood from the intestinal tract and observational studies have consistently shown negative associations of unmodified cows’ milk consumption with iron status indicators throughout infancy and early childhood.

The basic components of any infant milk, regardless of the formulation (powder or ready-to-feed), are proteins, fats, carbohydrates, vitamins and minerals. The major infant milk producers develop their own brands with a combination of each of these components. However, this must be achieved in accordance with the regulatory framework of the current Infant Formula and Follow-on Formula Regulations and any subsequent changes to the directive (if milks fall into those categories), or to regulations related to foods for special medical purposes. The basic nutritional profile of the majority of infant formula and follow-on formula is therefore very similar. All milks marketed in the UK must be notified to a Government competent authority (usually The Department of Health in England) before they are put on the market so that the composition (and labelling) can be checked against the regulatory framework.

The majority of infant milks start with a base of cows’ milk or goats’ milk (skimmed or full-fat, liquid or powder, or using demineralised whey protein concentrates) with added lactose or other carbohydrates, vegetable and other oils, vitamins and minerals. About 80% of the base powder for Danone Nutricia brand infant formula in Europe is made in Ireland and this base powder uses milk protein, demineralised whey and lactose with added vitamins and minerals and other ingredients from other sources. Other milks may be based on soya protein from soya beans, with added vegetable and other oils and maltose, maltodextrin or glucose polymers, or may be based on hydrolysed proteins.

For more information on the different ingredients used to make infant milks, please see www.firststepsnutrition.org

The manufacturing processes for most powdered infant milks are very similar. Powdered infant formula is manufactured using two general types of processes: a dry blending process and a wet-mixing / spray-drying process. Some manufacturers use a combination of these processes, and each has different risks and benefits with respect to the potential for product contamination by harmful bacteria.

In the dry blending process, the ingredients are received from suppliers in a dehydrated powdered form and are mixed together to achieve a uniform blend of the macronutrients and micronutrients necessary for a complete infant formula product. Dry blending does not involve the use of water in the manufacturing process, reducing the chance that harmful bacteria will become established in the plant environment in sufficient numbers to cause product contamination. However, the microbiological quality of a dry-blended product is largely determined by the microbiological quality of the constituent dry ingredients. In a dry blending process there is no heat treatment to destroy bacteria in the final product. Thus, if one or more ingredients in a dry-blended product are contaminated by even low numbers of harmful bacteria, these bacteria are likely to be present in the finished product.

In the wet-mixing / spray-drying process, ingredients are blended with water in large batches. The wet product is then homogenised, pumped to a heat exchanger for pasteurisation, and then spray-dried to produce a powdered product. This process has the advantage of ensuring a uniform distribution of nutrients throughout the batch, but some nutrients are destroyed. The pasteurisation step destroys harmful bacteria that may be present in the ingredients, so this process is much less dependent on the microbiological quality of ingredients. However, the wet-mixing / spray-drying process requires that the processing equipment be regularly wet-cleaned. This frequent wet-cleaning provides the moisture needed by bacteria to grow and become established in the plant environment. If not controlled, these bacteria can be a source of product contamination. Some nutrients are added after pasteurisation and the microbiological quality of these nutrients is critical, since the product may not receive further heating sufficient to destroy harmful bacteria.

Many infant formula contain either fish oils and/or use the animal-derived enzyme rennet during production. Rennet is used to separate curds from whey and, although vegetarian alternatives are available, they are not used by all manufacturers. Therefore, the majority of infant formula are not suitable for vegetarians. Although soya protein based infant formula are vegetarian and are advertised as suitable for vegetarians by manufacturers, these are not recommended for use in the first 6 months of life without medical supervision.

At February 2021, Similac Gold First Infant Milk, Kendamil First Infant Milk, Kendamil Goat First Infant Milk and Kendamil Organic First Infant Milk are suitable for vegetarians, however formulations can change, always check the  product label.

Currently there are no infant milks suitable for vegans on the UK market as even those that do not contain a source of animal protein contain vitamin D sourced from sheep’s wool. If an infant is not breastfed or is partially breastfed then a conversation is needed with families about the safest way to ensure an infant’s nutritional needs are met.

Soya protein-based infant formula is available but should not be routinely used for infants in the first year of life without medical advice. This is primarily due to concerns over the potential allergenic effect of soya protein-based infant formula in infants at high risk of atopy and the effects that the phyto-oestrogens present in soya protein-based formula might have on future reproductive health. Additionally, as the carbohydrate source in soya protein-based infant formula is maltodextrin rather than lactose, these milks have a greater potential to cause dental caries than animal milk based infant formula.

Families who choose a vegan diet for themselves and who breastfeed throughout the first year can move their child onto an unsweetened fortified non-animal milk at one year of age (with the exception of rice-based milk alternative) but care must be taken that the diet is nutritionally adequate.  It is recommended that parents who want to bring up their baby as a vegan seek expert advice to make sure that all their baby’s nutritional needs are met. Guidance on how to ensure a breastfed baby with a vegan mum gets all the nutrients he or she needs, can also be found in the resource Eating well: vegan infants and under-5s, which can be downloaded from www.firststepsnutrition.org/eating-well-resources

Some, but not all infant formula, are halal approved. Halal status may differ between different formulations of the same brand. For example, the powdered infant formula may be halal approved but the ready to feed liquid versions of the same infant formula might not. Always check the label of the product you buy. Individual product datasheets contain the latest data we have on each product formulation’s halal status. They can be found at www.infantmilkinfo.org.

Many manufacturers have now removed palm oil from their infant milks, however the main brands, Aptamil, Cow & Gate, Hipp Organic and SMA still use palm oil in some or all of their products. Manufacturers  may change the combination of oils used in their products as commodity prices fluctuate. Always check the label of the product you buy. Individual product datasheets  contain the latest data we have on the oils used in each product formulation. They can be found at: www.infantmilkinfo.org. 

Most infant milks for sale in the UK have the sugar lactose as the main source of carbohydrate, but a number of other carbohydrates are permitted by law depending on the type of formula and the protein source. Pre-cooked starch and gelatinised starch free from gluten are also permitted in limited amounts. Individual product datasheets contain the latest data we have on the carbohydrates used in each product formulation. They can be found at: www.infantmilkinfo.org

 

The majority of infant formula available on the UK market are composite foods made up by mixing different industrially produced dairy ingredients such as demineralised whey powder, lactose and dried skimmed milk powder with vegetable oils to approximate the macronutrient content of breastmilk. Vegetable oils supply approximately 50% of the energy in infant formula.  Some manufacturers also add a small amount of dairy fat to their products in the form of whole cows’ milk or milk fat. This reduces the amount of vegetable oil that is needed to achieve the required energy content for growth and development.

Historically, cows’ milk fat was the main source of fat in infant milks, however cows’ milk fat has higher quantities of the saturated fatty acids lauric acid and myristic acid, which may impact on serum cholesterol levels and lipoprotein concentrations, and the amount of these fatty acids in formula is restricted. Trans fatty acids are also naturally present in cows’ milk fat and may have negative health implications in high amounts, so there are also restrictions on trans fatty acids, which should not exceed 3% of total fat content in formula (Koletzko et al, 2005). Most infant milk manufacturers therefore use a blend of vegetable oils to ensure that their products meet the fat requirements specified in current regulations. Some manufacturers now add a proportion of fat to their products in the form of animal milk fat. This is added as either dried whole cows’ or goats’ milk, or as anhydrous milk fat, which is simply milk fat (butter fat) that has had all water removed. Claims that have been made for the addition of some anhydrous milk fat in infant milks include that it aids fat and calcium absorption, however there is a lack of evidence to support this.

The addition of a small amount of whole cows’ milk to infant formula does not increase the risk of the conditions that have been associated with using whole cows’ milk or unmodified cows’ milk formula as the main milk drink because cows’ milk is just one element of the ingredient mix and the composition of the whole product is regulated to ensure that the protein and mineral ions are maintained at safe levels.

 

Reference

Koletzko B, Baker S, Cleghorn G, et al (2005). Global standard for the composition of infant formula: Recommendations of an ESPGHAN coordinated International Expert Group. Journal of Pediatric Gastroenterology, 41, 584-599.

 

Are infant milks that contain A2 cows’ milk protein different to other infant milks?

A2 cows’ milk is milk from cows that have been bred to produce milk containing only the A2 β-casein protein. Standard cows’ milk contains both A2 and A1 β-casein. Other mammalian milks including human milk, goats’ milk, sheeps’ milk and camels’ milk are naturally A2 β-casein dominant.

Nutricia, who market the only A2 β-casein cows’ milk based formula milks in the UK do not currently provide any rationale for the inclusion of A2 milks in their product portfolio other than stating their popularity in other countries and their wish to give parents greater choice. In America Enfamil infant formula based on A2 milk protein is marketed as being easier to digest and as potentially being ‘a helpful alternative for babies with milk-related tummy discomfort’, however, the literature shows that there are no established health benefits for the use of A2 β-casein cows’ milk in infant milks.

Nutricia also suggest that this milk is ‘premium’ because cows producing only A2 milk are rarer. The relative rarity of A2 β-casein milk also means that infant formulas based on A2 milk are more expensive than those based on standard cows’ milk protein.

 

Oligosaccharides in human milk are complex carbohydrates that are known to support the developing infant’s immune system (Doherty et al, 2018). Three major categories of oligosaccharides found in human milk have been isolated: fucosylated and non-fucosylated neutral oligosaccharides which account for the majority of the oligosaccharides present in human milk, and sialylated acidic oligosaccharides which constitute about 12-14% (Smilowitz et al, 2014). The amount and composition of oligosaccharides in human milk vary between women, over the course of lactation and geographically, and more than 200 free oligosaccharide structures have so far been identified (Ruhaak and Lebrilla, 2012). The amount and variety of these complex carbohydrates are unique to human milk.

 

Two of the oligosaccharides present in human milk are being recreated artificially to add to infant milks. These are analogues of 2’-fucosyllactose (2’-FL) and Lacto-N-neotetraose (LNnT). These two analogues have been commercially available for several years, and whilst they are referred to as human milk oligosaccharides (HMOs) they are not sourced from human milk but are produced by microbial fermentation using genetically engineered micro-organisms including strains of E. coli and yeast (Sprenger et al, 2017).

 

The European Food Safety Authority (EFSA) consider these artificial HMOs as safe, novel foods (EU 2017/2470) and have said they can be added to infant formula and follow-on formula (EFSA, 2014). This approval relates only to their safety and does not imply any benefits. 

 

Some manufacturers have now added these HMOs to their products. Evidence from a single industry sponsored trial offered by Nestlé to support use in their Advanced infant formula products suggests significant health benefits, particularly related to reduced risk of infection and immune support (Puccio et al, 2017). This trial by Puccio et al, 2017 reported on differences between infections in infants fed a formula containing HMOs or a standard infant formula. The outcomes formed the basis of claims despite them being secondary outcomes which the trial was not powered to assess. Furthermore, the study sample was relatively small and some outcomes were only reported for sub-groups or at specific time points. A full review of this paper can be found in the statement on Nestle Advanced Infant Milk HMOs at https://www.firststepsnutrition.org/statements.

There are currently few published studies addressing the addition of HMOs to infant formula milks and those that are available report no clinical advantages for the addition of HMOs. 2’FL has been added to Similac formula in the USA where it is marketed as supporting infant immune systems.  Abbott reference their own clinical trial in healthy, term infants, to support their claims. Whilst their clinical trial reported some similarities in rates of absorption of 2’FL-HMO from either infant formula or breastmilk at day 42 of the trial between breastfed infants and those fed supplemented test formula, these similarities were no longer apparent at day 119 and no clinical advantage was shown (Marriage et al 2015). Results from a smaller study from the same clinical trial reported that biomarkers of immune function including circulating lymphocyte populations, immune cell proliferation, cell cycle analysis and respiratory syncytial virus (RSV) load did not suggest that infants consuming formula milk supplemented with 2’FL-HMO could develop immune function similar to that of infants fed human milk (Goehring et al., 2016). Some differences were noted for some of the cytokines measured, but the data overall was inconsistent with the idea that the supplemented formula impacted on immune response.

 

A review paper published by Vandenplas et al (2018), which included authors with significant affiliations to the infant formula industry, acknowledged that there are no established benefits for the addition of HMOs to infant formula and that more prospective randomised trials in infants are needed to evaluate any clinical benefit of supplementing infant formula with HMO’s. This has been reiterated in several review articles since (Chouraqui, 2020; Wiciński et al, 2020) and it is clear that there is insufficient information to suggest a health benefit from the addition of artificially created HMOs to infant milks.

 

References

Chouraqui JP (2020) Does the contribution of human milk oligosaccharides to the beneficial effects of breast milk allow us to hope for an improvement in infant formulas? Critical Reviews in Food science and Nutrition.  https://doi.org/10.1080/10408398.2020.1761772

 

Doherty AM, Lodge CL, Dharmage S, Dai X, Bode L, Lowe AJ (2018) Human milk oligosaccharides and associations with immune-mediated disease and infection in childhood: A systematic review. Frontiers in Pediatrics, 6, 91

 

European Food Safety Authority (2014). Scientific opinion on the essential composition of infant and follow-on formulae. EFSA Journal, 12 (7), 3760. Available at: http://www.efsa.europa.eu/en/efsajournal/doc/3760.pdf

 

Goehring K, Marriage B, Oliver J et al (2016) Similar to Those Who Are Breastfed, Infants Fed a Formula Containing 2′-Fucosyllactose Have Lower Inflammatory Cytokines in a Randomized Controlled Trial.The Journal of Nutrition, Epub ahead of print October 26, 2016 as doi:10.3945/jn.116.236919.

 

Marriage B, Buck R, Goehring C et al (2015). Infants Fed Lower Calorie Formula With 2’FL Show Growth and 2’FL Uptake Like Breast-Fed Infants. Journal of Pediatric Gastroenterology and Nutrition 61 (6) 649-658.

Puccio G, Alliet P, Cajozzo C, Janssens E, Corsello G et al (2017). Effects of infant formula with human milk oligosaccharides on growth and morbidity: a randomized multicentre trial. Journal of Pediatric Gastroenterology and Nutrition, 64, 624-631.

Ruhaak LR, Lebrilla CB (2012) Advances in analysis of human milk oligosaccharides. Advances in Nutrition, 3, 406S-414S Shulman RJ, Wong WW, Irving CS, et al (1983). Utilization of dietary cereal by young infants. Journal of Pediatrics, 103, 23-28.

 

Sprenger N, Lee LY, De Castro CA, Steenhout P, Thakkar SK (2017) Longitudinal change of selected human milk oligosaccharides and association to infants’ growth, an observatory, single center, longitudinal cohort study. PLoS ONE 12(2): e0171814.

 

Smilowitz JT, Lebrilla CB, Mills DA, German JB, Freeman SL (2014) Breastmilk oligosaccharides: structure-function relationships in the neonate. Annual Review of Nutrition, 34, 143-169.

 

Vandenplas Y, Berger B, Carnielli VP, Ksiazyk J et al (2018). Human milk oligosaccharides: 2’-Fucosyllactose (2’FL) and Lacto-N-Neotetrose (LNnT) in infant formula. Nutrients, 10, 1161-1173

 

Wiciński M, Sawicka E,J Gębalski J et al (2020) Human Milk Oligosaccharides: Health Benefits, Potential Applications in Infant Formulas, and Pharmacology. Nutrients 12, 266; doi:10.3390/nu12010266. Available at:  https://www.mdpi.com/2072-6643/12/1/266

 

 

 

 

No. There is no evidence that infant formula marketed for hungry babies offer any advantage, and it is recommended that a first infant formula is used throughout the first year of life if babies are not being breastfed. Infant formula marketed for hungry babies has a whey:casein ratio similar to cows’ milk with more casein than whey. It is suggested that a higher casein content can slow gastric emptying, resulting in greater satiety and a better night’s sleep, but there is no evidence to support this. For more information on hungry baby milks see www.infantmilkinfo.org.

Most children do not need an infant formula after 1 year of age and cows’ milk can be the main milk drink from 1 year of age for most children who are not breastfed. Whilst cows’ milk is the most widely consumed animal milk in the UK, other pasteurised animal milks may provide a suitable alternative. You can find further information on the role of different animal milks in young children’s diets in our briefing paper: ‘Animal milks in the diets of children aged 1-4 years’.

Where there are concerns about the quantity and quality of food consumed, health professionals may recommend continued use of first infant milk into the second year, but this is rare, and food should be the main source of nutrients for toddlers. From 1 year of age children should get the majority of their energy and nutrients from food.

No. We do not recommend that anyone attempts to make home-made infant formula. Home-made infant formula may not have an appropriate nutritional composition and therefore may not support proper growth and development. The ingredients themselves, or the way in which they have been prepared, increases the risk of severe bacterial infection in infants. Unlike commercially prepared infant formula, home-made infant formula are not subject to any compositional standards and their preparation, storage and handling have not been subject to risk assessment and subsequent recommendations for safe usage.

For nutritional composition information about specific products you can view our product datasheets here: www.infantmilkinfo.org

However, if you need to contact a manufacturer, please see the contact details below for breastmilk substitute manufacturers and their product lists.