Page 43 - Today's Dietitian (March 2020)

complex is that every individual has a
unique, diverse set of microbes.
The adult microbiome develops Register now for
primarily during the first three
years of life and is significantly our 2020 Spring
affected by what occurs during this
time. The colonization of the gut is
initiated during pregnancy. It’s been Symposium!
discovered that the womb isn’t a sterile
environment as once believed; bacterial www.TodaysDietitian.com/SS20
DNA has been found in the placenta,
amniotic fluid, and meconium. This
means that the maternal microbiome
is colonizing and influencing the gut The Microbiome’s Effect who were mostly vegetarian and eating
of the fetus. Once the infant is born, on Nutritional Status a diet high in dense starches such as
the microbiome is further shaped The gut microbiome affects the body’s millet, were found to have more bacte-
by gestational age, the type of birth ability to extract and use nutrients from roidetes in the gut. Researchers also dis-
(whether by cesarean section or food, but diet also influences the compo- covered that the guts of African children
vaginal), breast-feeding vs formula sition and health of the microbiome. Gut contained prevotella and xylanibacter,
feeding, maternal nutritional status, and bacteria also accomplish the following : 9 known to enable the body to digest plant
the timing of the introduction of solid polysaccharides for energy. These two
6
food. By the age of 3, children have fully • help harvest inaccessible nutrients or bacterial strains weren’t found at all in
developed gut microbiomes, similar to energy from the diet; the children living in Italy. Researchers
what they will have in adulthood. • assist in the synthesis of vitamins; believe the gut microbiome of the Afri-
Although every microbiome is • support drug metabolism and can children evolved to help this popula-
unique and influenced by a variety of increase bioavailability; tion extract energy from the indigestible
factors, families, particularly those • assist in gut cell renewal ; polysaccharides found in their starch-
10
who live together, tend to have similar • act as a barrier against gut patho- rich diet. Extraction of calories from
microbiomes. This similarity between gens; and dense starches wouldn’t be necessary for
family members may be related to a • produce short-chain fatty acids. 11 populations that didn’t consume these
shared environment and a similar diet. types of foods.
14
Pet ownership seems to increase the Changes in diet can modify the Other studies have evaluated the
amount of the microbiome that’s shared microbiome’s composition in as little impact of diet on the microbiome using
between family members. 7 as 24 hours, but long-term dietary pat- populations in more similar geographic
Although most of the microbiome terns also seem to determine the general areas. In a 2012 study, Zimmer and
12
develops early, it can change throughout types of microbes found in the gut. A colleagues compared the gut micro-
life. The microbiome is a living organism study of more than 60 mammalian spe- biomes of vegetarians, vegans, and
that can be affected by the type of food it cies found a strong correlation between omnivores living in Germany. The com-
receives and by its environment. In addi- certain types of microbes and dietary position of the microbiome differed
tion, antibiotic use, stress, and illness patterns. Carnivores tended to have dif- depending on the type of diet followed,
can modify its composition. ferent gut microbes than those of omni- but the total microbial count remained
But the microbiome isn’t just influ- vores or herbivores. Diversity—and thus the same among all study participants.
enced by us; it also influences our resilience—of gut microbes was highest Vegans and vegetarians were found to
health. It has several important func- among herbivores. 13 have greater microbial diversity and
tions, including assisting with digestion There have been several studies more microbes known for carbohydrate
and nutrient absorption as well as mod- evaluating the gut microbiomes of fermentation and short-chain fatty acid
ulating immune response. The health of different human populations, but production, which is expected, since
the microbiome can impact one’s risk of it’s hard to determine whether the a vegetarian or vegan diet tends to be
developing certain illnesses such as dia- differences seen among populations higher in carbohydrates. Other studies
15
betes and autoimmune disease. 8 are due to dietary patterns, the haven’t duplicated these findings.
Research in the field of health and the environment, or other factors. A 2016 observational study by Wu and
microbiome is only beginning, and the A 2010 study comparing children in colleagues found no differences between
interaction between the human body an African village in Burkina Faso with the gut microbiota of vegans vs omni-
and the microbes it houses remains children in Florence, Italy—populations vores when they lived in the same
complex. Although this field of study is that are considerably different in terms environment.
16
in its infancy, much is known about how of genetics, environment, and dietary But just as long-term dietary pat-
diet influences the microbiome and, in patterns—found significant variations terns can influence the gut microbiome,
turn, how the microbiome influences in the gut microbiomes between the so can immediate diet modifications.
our body’s ability to use nutrients. groups. The children living in Africa, A 2014 study by David and colleagues
MARCH 2020 • WWW.TODAYSDIETITIAN.COM 43