IssueM Articles

Kefir Milk Influences Behavior in Mice

The nearly 100 trillion bacteria that live in our gastrointestinal tract aren’t just involved in food digestion; they influence the health and function of the entire body. Mounting evidence suggests gut microbes may even influence the brain, including behavior. This connection between the gut and the brain is called the gut-brain axis and is a complex network of signaling pathways linking the central nervous system with the enteric (or gastrointestinal) nervous system.

Cows are one of our major domestic animals, with about 1.4 billion domesticated cattle being raised for meat and dairy all over the world. Humans have long drawn from the existing genetic variation in cattle populations to select a variety of breeds with useful traits. The sequencing of the cattle genome enhanced the selection of cattle by allowing the use of genomic tools to select traits.

The human gut microbiome is known to contain a large number of both bacteria and viruses. Viruses are absent from the infant gut at birth but colonize shortly after and can sometimes lead to gastrointestinal disorder. By one month of age, infants can have about a billion viruses per gram of stool, which is similar to the number of viruses present in older children and adults. But there is still a lot researchers don’t know about how viruses colonize the early infant gut to form the virus microbiome, known as the virome.

Over the last six months, scientists all over the world have put their planned research programs on hold and pivoted to study SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2). Milk researchers are no exception. Milk from mothers that have COVID-19, the illness caused by SARS-CoV-2, could be a source of antibodies directed against the virus. Like convalescent plasma (i.e., blood from recovered COVID-19 patients), these maternally-derived antibodies offer potential as a therapeutic to help severely ill patients. But human milk could also contain RNA from SARS-CoV-2, and possibly even infectious viral material. Telling infected mothers to stop nursing “just in case” is not an option, particularly in populations without access to human milk alternatives. There is urgency in identifying both therapeutics to help those with the most severe infections and to establish informed public health policy for nursing mothers that are COVID-19 positive. The vast number of investigators tackling these questions across institutions and countries offers promise that answers will soon be available.

A Gene that Helps Humans Consume Fermented Dairy

Humans have many unique attributes, as does the family of species within which humans evolved—the hominids. About 15 years ago, geneticists added to the list of hominid-unique attributes by noting that species within this family have a gene called HCA3 that other mammals lack. Now a group of researchers from Leipzig, Germany has figured out what this gene does and why it was preserved by natural selection. Their evidence suggests that HCA3 blessed the hominids with the ability to eat many bacteria-riddled foods without getting sick. These include some foods that played important roles in the story of human evolution, such as fermented milk products.

Malaria Antigens Occur in the Breast Milk of Asymptomatic, Infected Mothers

Malaria still accounts for approximately 435,000 deaths each year, and the substantial majority of these deaths—some 61%—are children under five years of age. Governments of affected countries, international aid organizations and foreign donors put in place various safeguards to reduce the disease rate, including mosquito nets and preventative malaria medicine for children. Yet the World Health Organization bemoans a lack of funding in this space. In 2017, for example, 15.7 million children in the Sahel region in Africa received seasonal malaria prophylaxis, but the paucity of program funding meant that 13.6 million children who could have benefited missed out.

Yogurt Consumption Is Associated with Reduced Mortality in Women

Given its beneficial effects on health, it’s perhaps not surprising that yogurt has been thought to increase lifespan. “Yogurt and other fermented milk products such as kefir have long been claimed to extend life expectancy by Eastern European countries such as Bulgaria,” says Dr. Karin Michels, now at the University of California, Los Angeles. “We were curious whether these claims would be supported by data,” she says.

Older Adult Bone Health Linked to Breast Milk in Infancy

Older adults looking to keep their bones strong might turn to a glass of milk with lunch to help meet their daily calcium and vitamin D requirements. New research suggests that older adults interested in healthy bones might also want to find out what they drank for lunch as an infant.

Research by Arla Food for Health, a public-private research partnership between Arla Foods, Arla Foods Ingredients, University of Copenhagen and Aarhus University addresses dietary guidelines for type 2 diabetics.

Feeding Method Affects Human Milk Microbes

It seems counterintuitive that breastmilk would be anything but sterile—human infants have a naïve and immature immune system and their first food should be free of potential pathogenic organisms, right? But study after study demonstrates that milk indeed contains microbes. Precisely where these microbes originate and how they make their way into human milk, however, is still being worked out. There are two, non-mutually exclusive hypotheses to explain their origins: one argues that milk microbes originate from the mother’s gut and are passed to the mammary gland (entero-mammary translocation) and the other that bacteria from the infant’s oral cavity move back into the mammary gland and influence the types and quantities of bacteria passed via milk (retrograde inoculation). Because not all milk microbes are equally beneficial for the infant, finding support for one or both of these hypotheses offers the potential of modifying the milk microbiome in ways that could improve infant outcomes.