What is colic?
Colic is a term used to describe the inconsolable crying in an infant which effects up to 20% of babies. Infantile colic is diagnosed if baby is crying for more than 3 hours a day, more than 3 times a week for more than 3 weeks .
How does colic present?
Colicky crying is often accompanied by clenched fists, drawn up legs and a red face, giving the appearance that baby is experiencing gastrointestinal pain. Unlike normal infant crying, colic often establishes a pattern where bouts of crying begin and finish at the same time each day. Ancient history in some cultures talk of a belief that newborns are able to see things that adults cannot, such as ghosts or spirits, and that this is what causes the unexplained, sudden crying.
Colic usually appears 2 to 3 weeks after birth and peaks at about 5 to 8 weeks, often resolving spontaneously by 4 months of age . Although colic is benign and self-limiting, it is a burden to families and health care professionals and is strongly associated with maternal depression and is a risk factor for shaken baby syndrome .
What causes colic?
There has been much research over the years into the causes of colic, however a defined cause is still unknown . It is likely that the causes for colic are multifactorial and a number of psychological, behavioural and biological components are thought to contribute .
The most researched causes of colic include:
- Infant gut development: alternations in gut microflora and inflammation [1-7], alterations in gut hormones [3,6], immature digestive system [1,5].
- Antibiotic use in early infant life 
- Allergy or intolerance to cow’s milk protein (though maternal diet or infant formula) [8-9].
- Allergy or intolerance to foods contained in breastfeeding mother’s diet [8-9].
Some factors that may increase the risk for colic include:
- Exposure to cigarette smoke [1,10]
- Family tension and parental anxiety 
- First born status 
Why is colic worse at night?
There is a theory that the circadian rhythm influences gut motility in infants. Serotonin which is the hormone precursor to melatonin (our sleep hormone) causes an increase in gut motility. It is thought that this increase in evening serotonin causes intestinal cramps, pain and discomfort which may attribute to the increase in colic symptoms at night. By about 3 to 4 months of age, when colic usually resolves, melatonin circadian rhythms are established. As only serotonin circadian rhythms are present at birth, it is thought to play a role in infantile colic [13-14].
Treatment for colic
Most research studies on colic are small and subject to bias, reducing the quality of research. For this reason, medical professionals are not able to recommend treatment for colic, as there is still much that is unknown. However, the following remedies have shown beneficial outcome in clinical studies with no adverse effects.
Remedies for colic that may improve symptoms include:
Probiotics modulate the composition of the intestinal microbiome by colonizing beneficial bacteria . Among other mechanisms, probiotics can reduce intestinal inflammation . Infants with colic display an increase in intestinal inflammation and gut microbiota dysbiosis, meaning they have less beneficial bacteria and more pathogenic bacteria compared to non-colicky infants [3, 15, 24,25]. The proposed mechanism of excessive crying includes painful intestinal contractions secondary to excessive gas or swallowed air. By improving the gut microbiota and reducing inflammation, the gastrointestinal symptoms of colic may be reduced. Administration of infant probiotics have been shown to reduce crying time in colicky infants compared to controls in several studies [15-19,26].
Prebiotics: Galacto-oligosaccharides and Human Milk Oligosaccharides
Prebiotics such as galacto-oligosaccharieds improve probiotic adherence by encouraging the growth of beneficial microbes in the gastrointestinal tract [3, 26]. Breastmilk contains naturally occurring prebiotics in the form of human milk oligosaccharides (HMO) which are the preferred fuel for biﬁdobacteria and lactobacilli, providing beneﬁcial eﬀects on the developing microbiome of breastfed infants. In contrast to galacto-oligosaccharides (GOS), HMO suppress potential gut pathogens, thereby providing protection against gastrointestinal infection and dysbiosis . In addition, a recent study showed a reduction in colic symptoms in caesarean born infants fed formula containing HMO .
Allergen-free maternal diet for breastfed infants
Breastmilk contains trace amounts of maternally ingested dietary antigens which may result in a hypersensitivity reaction in infants with colic. A number of studies have demonstrated a reduction in colic when breastfeeding mothers consumed a hypoallergenic diet (free from cow’s milk, wheat, eggs, soy, nuts, fish) . A small study found that maternal low FODMAP (fermentable oligo-, di- and mono-saccharides and polyols) diet was associated with a reduction in infant colic symptoms .
Researchers hypothesis that the immature digestive system of an infant may result in malabsorption of fat and other nutrients. Alternatively, the intestinal microflora may be abnormal, resulting in increased nutrient fermentations (associated with food allergens and FODMAPS) causing gas and colicky pain. Dietary restrictions of allergenic and fermentable foods in the breastfeeding mother’s diet may reduce colic symptoms in infants [3, 8-9].
Allergy specific infant formula for formula-fed babies
The dietary modifications for formula-fed infants involve decreasing or removing the intake of cow’s milk or changing the type of milk formula to specialty formulas. In formula‐fed babies, where an underlying allergy to cows’ milk protein is thought to affect the infant, extensively hydrolysed formulas, based on casein or whey, have been shown to reduce colic symptoms [3, 19-20].
Soy formulas are not recommended for infants under 6 months of age due to concerns that they can impact hormones in babies. This is because soy is a natural source of phytoestrogens and large amounts of soy can interact with hormones .
Herbal remedies may provide relief from colic pain by providing anti-spasmodic activity, helping to relax smooth muscle, reduce gastrointestinal inflammation and spasms causing pain. Herbal extracts such as fennel, chamomile, vervain, lemon balm and licorice have shown effectiveness in colic relief, although the research to date is small [3,15,21]. One study found that the average crying time was lower for infants given a herbal extract compared to infants given a placebo at the end of one-week intervention .
Pharmacological remedies are generally not recommended due to the uncertainty of effectiveness and possible adverse effects . Although Simethicone drops are often used to treat colic, a systemic review of three randomized trials found that they are no better than placebo at reducing colic .
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