Do Hispanic immigrants live longer thanks to their bacterial diversity?

Hispanic migrants have a higher life expectancy and scientists find it hard to pinpoint the exact cause. Bacteria could perhaps provide part of the answer.

Unexpected longevity

There are many explanations behind the unexpected longevity of Hispanic immigrants in the United States. Despite their lower economic status and high risk profile for cardiovascular disease, this group of migrants tend to live longer than expected. Scientists have formulated several theories to answer this “Hispanic Paradox.” This article will discuss an alternative hypothesis.

Previous hypotheses  include the following:

  • Hispanics tend to stick close together (Barrio advantage)
  • The self-selection of healthy migrant
  • The return of sick migrants (salmon bias)
  • Slower biology aging clock (epigenetic clock)
  • Traditional way of life e.g. food preparation and cooking.

In other words, both selection and cultural characteristics could help to explain why Hispanics live longer.

Hispanic migrants in the United States

The Latin American or Hispanic community in the United States is a heterogeneous ethnic group which has origins in Mexico, the Caribbean, Central America, South America, and other Spanish-speaking countries. This community makes up 17 percent of the population and form the largest minority group in the United States. Based on certain factors such as a low cardiovascular disease (CVD) profile and socioeconomic status, one would expect Hispanics to have a relatively low life expectancy. Interestingly however, this is not the case. In fact, their life expectancy is the highest among three major ethnic groups in the US

Bacterial diversity hypothesis

However, there might be another explanation as well: the bacterial or microbiome diversity hypothesis. In short this theory proposes that unexpected health outcomes of Hispanics might be partly explained by their acquisition of a diverse set of microbiota in the home setting. This diversity is in turn expected to be partly retained through horizontal transmission of bacteria within the close-knit community of the host setting.  However, the higher level of microbial diversity erodes as the process of acculturation affects the individual or the group.

Symbiosis between bacteria and humans

Bacteria in and on our bodies have co-evolved with human beings and can provide a strong symbiotic relationship with our bodies. The bacterial diversity is relevant as a different set of bacteria can have a different set of useful and sometimes essential functions in our bodies. Once you miss out on certain strains, certain bodily processes might not be covered to their full potential. Similarly, microbiota diversity is linked to a higher level of flexibility, stability, and disease protection.

It is therefore important to realise that going from less to more “developed” societies, the diversity steadily decreases.  In other words, agricultural societies have a higher diversity, while foraging communities have the highest level of microbial diversity. This discrepancy between societies with different sources of subsistence can be explained by a long list of factors involving modernity, especially medicine use such as antibiotics. This erosion of bacterial diversity can perhaps be seen as the factor behind “diseases of civilization” such as allergies, asthma, obesity, and diabetes.

Possible implications

If this hypothesis turns out to be valid, several questions will have to be answered by health professionals and policy makes. For instance:

  • Should we fortify our foods or make supplementation mandatory to all school-aged children?
  • Can migrant population perhaps enrich the microbial diversity of hosts?
  • Should we increase the number of strains that are available in our probiotics?
  • Are modern methods such as chemical sanitation of the indoor environment justifiable in terms of their health outcomes?

Of course, more research is needed and luckily more is to come. Keep tuned to the exciting world of the human microbiome.



Add comment