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Beyond Topical: The Microbiome with Dr. Kristin Neumann

Beyond Topical: An interview with microbiologist Dr Kristin Neumann

Welcome to Beyond Topical, a series of interviews with experts in a variety of fields that extends the discussion of skincare to explore some of the multitude of other factors that affect skin health. Because while supporting skin with well-formulated and strategic products such as the ones we make at Marie Veronique is imperative, there’s more to the equation.


Intro from Marie Veronique Nadeau:

Dr. Kristin Neumann is a microbiologist whose work is especially helpful when it comes to developing topicals because of her interest in the skin, where the research is not yet as extensive as that which exists in the area of the gut microbiome. Most importantly, she increases our appreciation of the other, non-gut microbiomes by reminding us not to make assumptions vis-à-vis what we’ve learned about the gut. In other words, comparisons between the gut and other microbiomes are hardly ever 1:1.

For example, diversity in a microbiome is not always desirable. A healthy vaginal microbiome has only a few microbial species, and a skin can be populated by only a few species in its microbiome and still be perfectly healthy. In fact, an aging skin tends to exhibit more diversity than a younger skin. The watchword when speaking of skin and vaginal microbiome health is not diversity, but rather balance.

An emphasis on targeting specific species may take a back seat in the future to more holistic studies, such as explorations of the relationships between the gut and other microbiomes, in particular the gut-skin axis and the gut-brain axis. Investigating the routes by which microbes and their metabolites travel to various parts of the body will enlighten us as to the microbiome interconnections within our bodies and their role in determining our overall health. 

The most interesting work is yet to come! And in the meantime, we’ll keep doing what we can to respect and support a healthy microbiome in our products by choosing strategic preservatives that protect the product in the bottle but leave the microbes on the skin alone. Balance is the order of the day!


What is the “microbiome”?

The human microbiome is the genetic content of all microbes (bacteria, fungi, and viruses) that colonize our body. Cell-wise we have a 1.3 to 1 ratio of microbes to body cells and the microbiome outnumbers our own genes 150-fold.

How can the microbiome be disrupted and what can we do to keep our microbiome healthy?

The microbiome is disrupted by our industrialized lifestyle. The seeding of the microbiome starts at birth, and we are seeing a lot of C-sections vs. vaginal births. When you have a C-section, the baby gets exposed to hospital germs and skin microbes whereas with vaginal birth, the baby gets exposed to vaginal microbes (Lactobacilli) and even some of the mother’s gut microbes. 

We are supposed to live outside and be surrounded by a diverse ecosystem of microbiota, which we don't meet indoors. We only feel good if we are squeaky clean, so we continuously wash off our skin’s microbes with surfactants. And we eat a lot of unhealthy, highly processed foods which foster the growth of inflammatory opportunistic microbes, leading to well-known western diseases like IBD, allergies, and depression.

So the rule of thumb is to get as close as possible to nature in every part of our lives. Use as little as possible products on and in your body, including cosmetics and medication. Eat a great variety of unprocessed, untreated fresh foods and exercise a lot, optimally outside.

What factors determine each person's microbiome? How unique is the microbiome of one person to another?

Genetics, age, gender, ethnicity, environment, diet, and lifestyle all factor into our microbiome and this explains why it is so diverse between each individual. Looking at the microbiome, we are 80-90% different from each other, compared to our genetics, which are 99.9% similar between individuals.

What is known about the skin microbes? What microbes would you want to see in the skin microbiome? What microbes would you not want to see on the skin? Why do dry skin areas have more microbial diversity?

We know that we have lost a lot of diversity because of our lifestyle, which is far away from nature. In contrast to indigenous groups that are untouched by our westernized lifestyle, our skin is dominated by certain microbes, such as C. acnes, S. epidermidis, and Corynebacteria. There is no gold standard for a healthy skin microbiome, but we know that the above-mentioned usual suspects are beneficial for us as long as they are in a good balance.

Dry skin areas are a more moderate ecosystem to live on, thus more different species are able to colonize it. In the areas with more sebaceous glands there's a lot of sebum, which is food for C. acnes, which dominates these areas. The moist areas are also more specialized, with less diversity than dry skin, but higher microbial density.

What skin conditions are related to the skin microbiome?

Every condition of the body is in some way related to the microbiome. Specifically for the skin we know that eczema and acne are correlated with a disturbed skin microbiome. But also dry skin, sensitive skin, aging skin, bacterial vaginosis, and non-healing wounds correlate with a microbiome out of balance.

What role does P. acnes play in acne formation in your opinion? 

It is well known that P. acnes is one very important microbe of our skin's microbiome. In the case of acne formation, different parameters lead to the proliferation of misbehaving P. acnes strains, which contribute to the problem.

What role does Staphylococcus aureus play in skin disorders like atopic dermatitis?

S. aureus is not supposed to survive on healthy skin. In disorders like atopic dermatitis the skin barrier is disrupted, which leads to a changed physiology of the skin and enables the growth of S. aureus. On one hand S. aureus likes a high pH, and on the other hand it is being controlled by a healthy microbiome, which is not present in skin with atopic dermatitis. Thus S. aureus overgrows the healthy microbiota and adds up to the disease.

What does diversity mean in terms of the microbiome? Does healthy skin require a diverse microbiome?

Diversity is not always the key to a healthy microbiome. It is rather the balance between all microbes, which is very different for different parts of the body. In a lot of cases, a high diversity is equivalent to a balanced microbiome, but in some cases this is not true. For the vaginal microbiome, we actually need very few, very specific microbes to be healthy. Aging skin also shows a higher diversity compared to younger skin.

How similar is the microbiome of the skin to the microbiome of the gut? Can we make assumptions for the skin microbiome based on research into diversity and microbial behavior of the gut microbiome?

The gut microbiome definitely influences the skin microbiome and skin physiology via the Gut-Skin axis. The composition of the gut microbiome differs completely from the skin microbiome. It is as if you would compare the inhabitants of the rainforest with the inhabitants of the ocean, and even more complex, because the skin harbors many different ecosystems which in turn differ a lot from each other. Thus we cannot make assumptions from what we know about the gut and transfer that 1:1 to the skin.

Can you speak briefly about antimicrobials and the future of antimicrobials in relation to antibiotics?

Commonly used antimicrobials do not work selectively, which means, they are not only attacking the harmful pathogenic microbes, but also the ones we need to maintain a healthy balance. Besides the problem of resistance development, which is more likely with un-specific working antimicrobials, we are also facing the problem with unspecific killing of our microbiota. This is something one should always consider when taking antibiotics.

Regarding the future of antibiotics, hopefully new arising technologies will take over: one example is phages, which are viruses that specifically attack bacteria. Phage therapy or the (modified) endolysins deriving from phages are a great solution to the selectivity issue. While bacteria can develop resistance against phages very quickly, the modified endolysins (Artilysin®) offer a solution to the development of resistance.

What is your opinion on probiotic therapy and taking a supplement daily for wellness? Should we really be thinking about different and varied ways to support bacterial diversity based on different areas of the body, both topically and internally? Or is a targeted, overall microbial-supporting approach sufficient?

Probiotics may have a beneficial effect but they must be taken with caution and they are not the solution for a healthy life. They might contribute to wellness, together with a variety of other ways to support a healthy microbiome, such as a fresh and diversified diet, exercise, and living as close as possible to nature. In any case, before using probiotics, one should choose the probiotic very carefully, check the data and see if this specific probiotic meets one’s specific need. In the best case, one should consult an expert for probiotics and nutrition.

What is the future of microbiome studies? Can you address interconnectedness between microbiomes?

The microbiome studies are part of a holistic approach towards health. This is kind of a movement into the right direction, which is focused on prevention rather than treating. As all organs in our body, also our microbiome is connected body-wide. We know about the gut-skin axis, which sounds familiar because we know that what we eat also affects our skin. Then there's the gut-brain axis via the vagus nerve but also via microbial metabolites that reach the brain via the bloodstream. Those are what give us that sensation known as the "gut feeling" – the gut as our second brain. These are well studied microbiome interconnections within us, but there's more to come.



We are always excited to learn more about how microbiome research is evolving, particularly when it comes to caring for the skin. As ever, we are reminded that it is critical to create an environment in which our microbiota can thrive. As Louis Pasteur pointed out, “the terrain is everything.”  

While all of Marie Veronique's products consider the health of the skin's microbiome, two key topicals that are strategic towards maintaining microbial balance are our Balancing HypoTonic and Pre + Probiotic Daily Mist. They also happen to be especially popular during the summer months for their refreshing feel! 

A super hydrating tonic that calms and soothes the skin, Balancing HypoTonic offers an instant and noticeable refresh. It also promotes microbial balance and preps the top layers of the skin for optimum absorption of serums and oils.

Pre + Probiotic Daily Mist is a deeply hydrating and anti-inflammatory mist intended to promote skin health by providing humectants with distinct similarity to the skin’s lamellar structure. This not only promotes the balance of lipids and liquids, it also restores and improves overall barrier function, resulting in plump, calm skin. It may be reapplied throughout the day for added hydration and soothing elements, and also acts as a fixative for makeup.


Any topic discussed in this article is not intended as medical advice. If you have a medical concern, please check with your doctor.