Many people suffer from a variety of food-aversions. (Scientific research defines “aversion” as “a strong dislike associated with food illness or gastrointestinal discomfort”.) A study conducted with more than 500 undergraduate students in the USA found that up to 65% of the students reported that they suffered from at least one food aversion, while another study with nearly 1,500 subjects reported that about 5% of the population had milk and butter aversions.
Food-aversions can be caused by a variety of triggers that cause an unpleasant feeling when eating or drinking. Texture, for example, puts many people off foods; examples are peas and liver. The same holds true for other senses like taste and smell. However, many food-aversions start off when an individual eats a food and then becomes ill afterwards.
This can vary from a once-off bout of vomiting and diarrhoea which may or may not have been caused by the specific food, to repeated symptoms of illness after eating one or more foods. For example people who are allergic to soya will develop flatulence, cramps and nausea every time they eat a food that contains soya.
Read: Nausea and vomiting
If the foods in question are important sources of vital nutrients (e.g. milk and dairy products provide calcium, high quality protein and riboflavin to the diet), then the aversion can cause dietary imbalances. Consequently scientists are currently interested in trying to find ways to reverse food aversions, particularly those that cause dietary imbalances.
Milk and dairy foods and lactose intolerance
In view of the fact that the 1 June was World Milk Day, it is interesting to see how milk-aversion can be successfully overcome.
Milk and dairy products can cause unpleasant reactions such as the flatulence, abdominal pain, cramps and diarrhoea, linked to lactose maldigestion. This condition is associated with the inability to digest milk sugar or lactose because of a deficiency of the lactase enzyme. To a large extent lactose intolerance/maldigestion is dose- and situation-dependent. Scientists have found that the majority of lactose intolerant patients can tolerate up to 1 cup of milk a day.
As the most bioavailable and abundant source of calcium in the human diet, helping people who are lactose intolerant or those who have a milk-aversion to be able to consume milk and dairy products would greatly improve their diets and bone health.
Self-imposed reasons for avoiding milk
In addition to individuals who suffer from established lactose intolerance, there are many people who believe that they are “sensitive to milk and dairy products” and need to avoid them at all costs. This could be due to symptoms caused by other conditions such as irritable bowel syndrome (IBS) which also causes flatulence, abdominal pain, cramps and diarrhoea! In such cases milk and dairy may be innocent scapegoats.
Finally there is the category of people who have learned to avoid milk and dairy as a learned response. In many cases, a single bout of illness after consumption of a food type such as milk can trigger a lifetime of aversion which may not be based on reality.
In view of these variations in the human reaction to milk and dairy foods, Lauren O’Conner and her team of researchers at the Department of Nutrition Science of Purdue University in the USA, set out to test if 21 days of milk drinking intervention could reverse milk-aversion.
Twenty-seven participants (15 lactose digesters and 12 lactose maldigesters) between the ages of 18 and 55 years at a Midwestern University, who had been avoiding milk for at least one year, participated in the 21 day study. These milk avoiders included both lactose-intolerant (maldigesters due to lack of an enzyme) and tolerant (digesters), who were taught how to gradually introduce increasing quantities of milk into their diets.
The goal of the study was to increase liquid cow’s milk intake from half a cup of milk twice a day (week 1), to two thirds of a cup of milk twice a day (week 2), and then to a full cup of milk twice a day (week 3).
Read: Allergy-free milk?
The subjects were tested for milk-aversion, and how much they liked milk. In addition, their dietary intake with special emphasis on calcium intake was determined, and hydrogen breath tests were carried out. Lactose maldigesters produce higher levels of hydrogen in their breath when they are fed a test dose of 20 g of lactose dissolved in water. The subjects were also asked to keep records of their symptoms during the study.
The participants were followed up after 3 and 6 months to determine if the intervention had influenced the participants’ perception of and tolerance for milk, and their tendency to use milk more frequently.
Results of the study
The results showed that both the subjects with, and without lactose intolerance, exhibited a statistically significant decrease in the number of symptoms they recorded as they got used to increasing quantities of milk. Interestingly, the maldigesters (people who suffered from actual lactose intolerance), had a greater decrease in symptoms than the digesters. This supports previous findings that even patients with lactose intolerance can consume up to 1 cup of milk a day without untoward symptoms.
Feelings of aversion decreased until a plateau was reached at about 6 months. At the same time the subjects reported an increase in liking for milk which also reached a plateau at 6 months.
On average, milk consumption increased to about 10 servings per month at the 3-month follow-up, which improved calcium intake from a poor intake at baseline of less than 700 mg of calcium per day to fair (700 to 100 mg of calcium a day) at 3-6 months. This increase in calcium consumption was significant and a welcome improvement in dietary intake, considering that the majority of Americans have a sub-optimal calcium intake. A lack of calcium in the diet can lead to osteoporosis in both men and women, hypertension and certain cancers.
O’Conner and her team concluded that “the results suggest a reversal of milk avoidance”. The study showed that milk avoiders can increase their liking of milk and learn to incorporate milk into their diets after being exposed to increased amounts over a 21 day period.
The nutritional benefit of reversing milk avoidance and increasing the use of milk in one’s diet is of course the improved intake of bioavailable calcium, which helps to prevent osteoporosis and hypertension and may help against certain cancers. An adequate calcium intake also benefits a number of metabolic functions – it strengthens bones and teeth, helps to control weight gain and improves resistance to diseases.
The results of this study are encouraging and will hopefully prompt dieticians to help their milk-averse patients to overcome their dislike of this calcium-rich food. In addition, this study shows that it should also be possible to reverse other food-aversions. Hopefully researchers will continue to conduct studies to investigate if other food-aversions can also be overcome.
- O’Conner L E, Eaton TK, Savaiano D A (2015). Improving milk intake in milk-averse lactose digesters and maldigesters. Journal of Nutrition Education & Behavior:1-6.