Infant formula
Infant formula is an artificial substitute for human breast milk. Formulas are designed for infant consumption, and are usually based on either cow milk or soy milk. Use of infant formula has been decreasing in industrial countries for over forty years as a result of antenatal education, increased understanding of the risks of infant formula, and social activism. A 2001 report of the World Health Organization strongly advocates breastfeeding over the use of infant formula except in unusual circumstances.

# History of formula

## Early infant foods
Throughout history, mothers who could not (or chose not to) breastfeed their babies either employed the use of a wet nurse or, less frequently, prepared food for their baby, a process known as "dry nursing."  Baby food composition varied according to region and economic status..  In Europe and America during the early 19th century, the prevalence of wet nursing began to decrease, while the practice of feeding babies mixtures based on animal milk rose in popularity.
This trend was driven both by cultural changes as well as increased sanitation measures, and it continued throughout the 19th and much of the 20th century, with a notable increase after Elijah Pratt invented and patented the India-rubber nipple in 1845. As early as 1846, scientists and nutritionists noted an increase in medical problems and infant mortality was associated with dry nursing.  In an attempt to improve the quality of manufactured baby foods, in 1867, Justus von Liebig developed the world's first commercial infant formula, Liebig's Soluble Food for Babies.  The success of this product quickly gave rise to competitors such as Mellin's Infant Food, Ridge's Food for Infants and Nestle's Milk.

## Raw milk formulas
As physicians became increasingly concerned about the quality of such foods, medical recommendations such as Thomas Morgan Rotch's "percentage method" (published in 1890) began to be distributed, and gained widespread popularity by 1907.  These complex formulas recommended that parents mix cow's milk, water, cream, and sugar or honey in specific ratios to achieve the nutritional balance believed to approximate human milk reformulated in such a way as to accommodate the believed digestive capability of the infant.
At the dawn of the 20th century in the United States, most infants were breastfed, although many received some formula feeding as well.  Home-made "percentage method" formulas were more commonly used than commercial formulas in both Europe and the United States.  They were less expensive and were widely believed to be healthier. However, formula-fed babies exhibited more diet-associated medical problems, such as scurvy, rickets and bacterial infections than breastfed babies.  By 1920, the incidence of scurvy and rickets in formula-fed babies had greatly decreased through the addition of orange juice and cod liver oil to home-made formulas.  Bacterial infections associated with formula remained a problem more prevalent in the United States than in Europe, where milk was usually boiled prior to use in formulas.

## Evaporated milk formulas
In the 1920s and 1930s, evaporated milk began to be widely commercially available at low prices, and several clinical studies suggested that babies fed evaporated milk formula thrive as well as breastfed babies  (these findings are not supported by modern research.)  These studies, accompanied by the affordable price of evaporated milk and the availability of the home icebox initiated a tremendous rise in the use of evaporated milk formulas.  By the late 1930s, the use of evaporated milk formulas in the United States surpassed all commercial formulas, and by 1950 over half of all babies in the United States were reared on such formulas.

## Commercial formulas
In parallel with the enormous shift (in industrialized nations) away from breastfeeding to home-made formulas, nutrition scientists continued to analyze human milk and attempt to make infant formulas that more closely matched its composition.  Maltose and dextrins were believed nutrionally important, and in 1912, the Mead Johnson Company released a milk additive called Dextri-Maltose.  This formula was made available to mothers only by physicians.  In 1919, milkfats were replaced with a blend of animal and vegetable fats as part of the continued drive to closer simulate human milk. This formula was called SMA for "simulated milk adapted."
In the late 1920s, Alfred Bosworth released Similac (for "similar to lactation"), and Mead Johnson released Sobee.  Several other formulas were released over in the next few decades, but commercial formulas did not begin to seriously compete with evaporated milk formulas until the 1950s.  The reformulation and concentration of Similac in 1951, and the introduction (by Mead Johnson) of Enfamil in 1959 were accompanied by marketing campaigns that provided inexpensive formula to hospitals and pediatricians.  By the early 1960s, commercial formulas were more commonly used than evaporated milk formulas, which all but vanished in the 1970s.  By the early 1970s, over 75% of babies in the United States were fed on formulas, almost entirely commercially produced. 
When birth rates in industrial nations tapered off during the 1960s, infant formula companies heightened marketing campaigns in non-industrialized countries. Unfortunately, poor sanitation led to steeply increased mortality rates among infants fed formula prepared with contaminated (drinking) water. Organized protests, the most famous of which was the Nestle boycott of 1977, called for an end to unethical marketing. This boycott is ongoing, as the current coordinators maintain that Nestle engages in marketing practices which violate the International Code of Marketing of Breast-milk Substitutes.

## Resurgence of breastfeeding
In the 1960s and 70s, a dramatic increase in breastfeeding began to occur in industrialized countries worldwide.  Unlike the shift to home-made formula in the early 20th century, or the shift to commercial formula in the 1950s, this movement seems to have arisen from the general public rather than from the health profession.  Various sources have cited the woman's liberation movement, negative publicity against the formula industry, and better antenatal education of mothers.  Continued research has shown that breast milk provides unique benefits to both babies and mothers, including reduced incidence of food allergies, stronger immune response, and reduced infant hospitalization.
Initiatives have begun to encourage a resurgence of breastfeeding mothers. As a result of the International Code of Marketing of Breast-milk Substitutes, infant formula companies are now required to preface their product information with statements that breastfeeding is the best way of feeding babies and that a substitute should only be used after consultation with health professionals. However, the vast majority of infant formula manufacturers ignore other parts of the code, including the bans on advertising, offering free samples, and issuing coupons.
There are some common reasons that infant formula is used.  They include (but are not limited to) mothers who are infected with HIV or have untreated, active tuberculosis, mothers who are taking prescribed medication or who are addicted to recreational drugs that could have adverse affects on the baby if passed on through breastmilk, infants who have been adopted, although some adoptive mothers are  able to induce lactation instead of using artificial infant milk, and infants who have birth defects making them physically unable to breastfeed, although many mothers are successful in expressing breast milk to feed their infants, women who are physically unable to breastfeed due to mastectomy, and mothers who do not desire to breastfeed. Some studies have shown that not breastfeeding one's infant can increase the risk of infection and disease, both immediately and later in life, for infants and for their mothers. Infant formulas cannot reproduce the immune protection of human breast milk.

# Nutritional content
Besides breast milk, infant formula is the only other infant milk which the medical community considers nutritionally acceptable for infants under the age of one year. Cow's milk is not recommended because of its high protein and electrolyte (salt) content which may put a strain on an infant's immature kidneys. Evaporated milk, although perhaps easier to digest due to the processing of the protein, is still nutritionally inadequate.
Most of the world's supply of infant formula is produced in the United States. The nutrient content is regulated by the American Food and Drug Administration (FDA) based on recommendations by the American Academy of Pediatrics Committee on Nutrition. The following must be included in all formulas produced in the U.S.:
- Protein
- Fat
- Linoleic acid
- Vitamins: A, C, D, E, K, thiamin (B1), riboflavin (B2), B6, B12
- Niacin
- Folic acid
- Pantothenic acid
- Calcium
- Metals: magnesium, iron, zinc, manganese, copper
- Phosphorus
- Iodine
- Sodium chloride
- Potassium chloride
In addition, formulas not made with cow's milk must include:
- Biotin
- Choline
- Inositol

# Variations
Infant formula is available in powder, liquid concentrate and ready-to-feed forms, which are prepared by the caregiver or parent in small batches and fed to the infant, usually with either a baby bottle or cup.   It is very important to measure powders or concentrates accurately to achieve the intended final product. It is advisable that all equipment that comes into contact with the infant formula be cleaned and sterilized before each use. Proper refrigeration is essential for any infant formula which is prepared in advance, since infant formula is especially susceptible to bacterial growth.  Powdered, cow's milk-based infant formulas are not recommended for premature or sick infants, or for infants under one month of age.  Powdered infant formulas are not sterile and may be contaminated with Enterobacter sakazakii, bacteria that may lead to neonatal meningitis, sepsis and necrotizing entercolitis in infants with weak or compromised immune systems.

# Hypoallergenic formulas
Baby formula can be synthesized from raw amino acids. This kind of formula is sometimes referred to as elemental infant formula or as medical food because of its specialized nature. While quite expensive, such formula is hypoallergenic and is sometimes used for babies with severe allergies to cow's milk and soy. Some commercial brands are Neocate and Peptamen. Being purely synthetic monomeric amino acids, it is also quite foul-tasting to adults.

# Controversy and science
The use of infant formula itself has come under scrutiny.  Many scientists believe that infant formula exposure increases the risk of several conditions including insulin dependent diabetes mellitus  asthma, and eczema. It is well-established that non-breastfed infants suffer significantly more middle ear infections, respiratory, intestinal and other bacterial infections . An association with lower cognitive development has also been shown in several studies . The U.S. government has identified breastfeeding as an important measure of infant and maternal health. However, it is also believed that later-life conditions that are associated with formula-fed babies are the result of a multitude of factors. For instance, while it is often noted that formula-fed babies are at greater risk for obesity, it is also true that formula-fed babies who live in households in which proper nutrition and physical activity are emphasized generally fare well.
Breastfeeding experts and the American Academy of Pediatrics contend that feeding anything (even breast milk) to a child with a bottle can interfere with successful establishment of breastfeeding in the first two months. Supplementing with formula also decreases breast milk supply in proportion to the amount of substitute offered, however pumping breast milk when a substitute is offered can eliminate this drop in breast milk supply. Bottlefeeding can be less successful than breastfeeding in promoting the natural bonding process of mother and child.  (See The Womanly Art of Breastfeeding below).
Infant formulas, like other processed food products, are the subject of occasional recalls, usually due to bacterial or foreign object contamination. Recently, infant formula has been recalled in several countries other than the U.S. for nutrient deficiencies leading to infant illness and death.  Though infant formula is available without a prescription, it is generally recommended that its use be under the supervision of a medical professional. The health professionals most knowledgeable about breastfeeding are IBCLCs: International Board Certified Lactation Consultants (see IBLCE, below).
Many newer infant formulas containing DHA, ARA and other fatty acids are being aggressively marketed via direct mail, print advertisements and other channels in the United States, Canada and other developed nations.  Human breast milk DHA concentrations range from 0.07% to greater than 1.0% of total fatty acids, with a mean of about 0.34%.  These formulas often contain lower amounts however the marketing may suggest that these formulas provide cognitive and developmental benefits surpassing those of breast milk. Studies by formula companies suggesting these results are vague and often lacking in sample size and length.  In addition these studies often compare these new formulas to older formulas rather than breast milk alone.  This information may be misleading to new mothers receiving samples often only days after the birth of a new child. In the United States formula is regulated by the FDA as a food product only. The FDA does not have the authority to oversee the claims of formula companies.  These efforts may result in more mothers terminating breast feeding earlier than recommend due to the perceived benefits of these new formulas.
Ventria Bioscience owns patent number 6,991,824, which is an invention directed to improving infant formula.  The invention uses genetic engineered transgenic plants containing protein expressions of human milk.  The expressed proteins include lysozyme and lactoferrin.

# Manufacturers
Major infant formula manufacturers include:
- PBM Products: The first to introduce store brand formula in the U.S.
- Mead Johnson: owned by Bristol-Myers Squibb, makes Enfamil
- Nestle: the largest producer of formula in the world, makes Good Start
- Ross Pediatrics: a division of Abbott Laboratories, makes Similac
- Wyeth Nutrition: Market leader in the Philippines
S-26 Gold, Promil Gold, Progress Gold, S-26, Promil, Promil Kid, Bonna, Bonamil, Bonakid 1+, Bonakid 3+, Nursoy
- Parent's Choice
- Bright Beginnings
- Gerber Products Company
- Royal Numino Dumex, Milupa