Interview with Prof. Dr. Michaela Axt-Gadermann
Beautiful skin and a healthy intestine: is one related to the other?
Prof. Dr. Michaela Axt-Gadermann: Yes, there is actually a very close connection between the skin and the intestines and the microorganisms that live in them . Typical changes in the intestinal flora, but also in the skin flora, can be found in a large number of skin diseases. Often these disorders of the microbiome even precede skin diseases by months or years, as has been shown in various studies. We know this from diseases such as neurodermatitis and rosacea, but also from asthma or obesity.
Damage to the microbiome, for example, antibiotics, bad eating habits or too much hygiene has negative effects on the immune, nervous and endocrine systems of the body . These do not show up suddenly, but develop slowly. The consequences of this “dysbiosis” therefore become noticeable with a delay. And the effects can not only be felt in the intestines, but also involve the entire organism and thus also the skin.
On the other hand, the intestinal flora naturally also has positive effects on our skin . Intestinal bacteria produce vitamins such as the skin and hair vitamin biotin or other B vitamins. They can stimulate the formation of antioxidants, hyaluronic acid, lactic acid or ceramides, i.e. all substances that one would actually expect in cosmetic products. For example, certain probiotic bacteria are able to soothe sensitive skin.
They address the skin flora. How important is it for healthy skin?
Dr. Axt-Gadermann: Not only our intestines but also our skin are densely populated with beneficial bacteria . If this community, the so-called skin flora, is in balance, then our skin is doing well. It is then protected from the spread of undesirable germs, can regenerate itself well, the protective acid mantle and the skin barrier are intact, which means that more moisture can be stored in the skin.
However, similar to the intestinal microbiome, the skin microbiome can also be damaged. Too frequent showering, incorrect body care or, here too, too much hygiene or antibiotics put a strain on the skin microbiome. As a result, unwanted bacteria can then spread. This is the case with acne or possibly with neurodermatitis. In the latter, a certain germ, the so-called “Staphylococcus aureus” , spreads excessively.
One study has shown that the more of these bacteria live on the skin, the worse the eczema and itching. So far there have been few options for gently and effectively eliminating these microorganisms. In our own study, we were able to prove that these dangerous bacteria can be reduced by more than 80 percent within two weeks with the help of a skin treatment with live probiotic bacteria.
Suppose someone has skin problems and wants to know if their diet could be to blame? What can the person do to find out?
Dr. Axt-Gadermann: We now know different eating habits and also certain foods that can worsen certain skin diseases. In order to find out whether a skin disease is possibly influenced by the diet, a food diary helps , in which you enter everything you eat and at the same time rate the skin condition with school grades. Often patterns can then be identified after a few weeks. Important: It often takes a day or two for food to affect the condition of the skin, so always see what happens after a day or two.
In the next step, foods identified as “suspicious” should be left out for a few weeks and the skin condition should be monitored further. If the skin doesn’t improve after three to four weeks , it is unlikely that these foods have anything to do with the skin condition.
If food allergies are suspected, an allergy test can also be useful. It is advisable to carry out a so-called RAST test (IgE antibodies). The IgG tests that are often offered are not very informative.
However, an allergy test is not always useful or necessary . The worsening of acne from dairy products or rosacea or psoriasis from spicy food is not caused by an allergic reaction, but is subject to other mechanisms that cannot be easily checked in the blood.
In your opinion, which foods should you avoid if you value healthy skin?
Dr. Axt-Gadermann: There are general and special recommendations here. In principle, meals rich in fat and carbohydrates such as fast food, many (not all) ready meals, sweets or soft drinks are not ideal for our skin. As a rule, they do not provide enough skin-friendly nutrients and can promote inflammation.
For some skin diseases, however, it has now also been possible to identify individual foods that can worsen the symptoms of many, but not all, of those affected. For some acne patients, these are mainly dairy products and foods with a high glycemic index , such as white flour products, sweets and soft drinks.
Spicy dishes, hot foods or drinks and alcohol – even in small quantities – often cause rosacea to “bloom”. Psoriasis patients also often react to spicy food and alcohol by worsening their skin condition.
Atopic dermatitis, food allergies are common, but not always . Above all, dairy products, eggs, fish, products made with wheat or rye flour, soy and certain types of fruit, as well as spices, contain substances to which many react with allergies. These should be avoided if the test is positive.
What foods would you recommend eating particularly often in order to get healthy skin?
Dr. Axt-Gadermann: Scientists have tried to find out what people eat who look younger. But that’s not that easy to say, because the studies that have examined it differ enormously in some cases.
In principle, however, it can be concluded from the results that a balanced diet with many antioxidants , which are contained, for example, in berries, intensely colored vegetables, dark chocolate, coffee and espresso, green tea, spices such as turmeric and rosemary, healthy fatty acids from rapeseed oil, Linseed oil, oily fish such as salmon, tuna, herring, mackerel, little sugar and enough protein seem to be the basis for beautiful skin.
How do you eat personally? What are your favorite dishes for beautiful skin?
Dr. Axt-Gadermann: I try to have a very varied diet with lots of fresh fruit, vegetables and whole grain products . Sufficient protein intake is also important for beautiful skin, because proteins provide the starting materials for collagens and elastic fibers, and these ensure firm tissue. There are also certain foods that are known to be beneficial for our skin.
Here is some good news for lovers of dark chocolate in particular : In a study in which test subjects consumed dark chocolate with a very high polyphenol content for three months, the moisture supply to the skin increased and even small wrinkles disappeared. Fortunately, I love to eat them. There are even some with 99% or 100% cocoa. But be careful: this does not work with commercially available milk chocolate due to the low polyphenol content.
I also regularly drink green tea and eat fruits and vegetables that contain carotenoids that protect the skin , such as carrots, watermelon, green leafy vegetables, sweet potatoes and tomato products. By the way: You don’t have to eat all of this raw: A tomato sauce, for example, provides more and better usable carotenoids than fresh tomatoes.
How much influence can you really have on your skin with your diet? Where is the limit from which you should resort to other measures, such as cosmetic products or pharmaceuticals?
Dr. Axt-Gadermann: With the help of nutrition, short-term and long-term effects can be achieved. A British study showed that eating carotenoid-rich fruits and vegetables in abundance within four to six weeks gives the complexion a more attractive color. Even with skin problems, if certain foods are jointly responsible for the symptoms and you omit them, you can achieve an improvement within four to eight weeks.
Other effects, such as delaying the signs of aging, take more time. Here, a healthy lifestyle at a young age often only pays off in middle age. A large British study with more than 4,000 participants between the ages of 40 and 74 showed that those who were particularly rich in vitamin C had noticeably fewer wrinkles. The same applies to foods rich in carotenoids.
If you compare the amount of wrinkles and age spots in 50-year-olds and then relate them to the antioxidants, especially the carotenoid content of the skin, then it can be clearly demonstrated that people who have a high concentration of protective substances in the skin are clear have fewer wrinkles and furrows than the less well cared for study participants.
However, it must be taken into account that people who consciously pay attention to their diet usually smoke less, drink less alcohol and also pay attention to their health in other ways. All of these parameters also have a strong influence on skin health.
However, cosmetic products are also important. When it comes to cosmetics and nutrition, there should actually be no “either-or”, but rather “both-and-also”. Nutrition and care complement each other when it comes to healthy skin.
Sun protection products are enormously helpful, for example, as UV light is one of the strongest skin aging accelerators. Cosmetics can also be used to add protective substances such as vitamin C, vitamin E or plant extracts to the skin.
What has more influence on the complexion, diet or care products?
A German team of dermatologists examined how the levels of protective substances differ when such antioxidants are supplied either from the outside as a cream, from the inside as a dietary supplement, or in combination. The result was clear: the clearly best values were achieved when antioxidants were both ingested and applied. When using cosmetics alone, a high concentration of antioxidants in the skin could be achieved very quickly, but after the end of the application, the protective substance level had dropped sharply again after two weeks.
The antioxidants are quickly removed from the outer layer through washing, textile contact and the natural rejection of the horny cells , or they are broken down by UV light. Of course, this also applies to other cosmetic ingredients.
If, on the other hand, antioxidants were only supplied from within, the body created a depot in the tissue and gradually released the protective substances to the surface of the skin in the form of sweat and sebum. As a result, the effects persisted for another five weeks, even after no further dietary supplements were taken.
However, when it was taken internally alone , the levels were lower than in the “inside-outside combination” and it also took longer for the nutrients to migrate into the skin.
What other factors can damage our skin?
Dr. Axt-Gadermann: Of course, lifestyle is very important. Smoking, sunbathing, lack of sleep and constant stress cause the skin to age faster. It has been known for a long time. But current studies have revealed other factors that damage the skin.
Environmental pollutants such as ozone, soot and fine dust accelerate the breakdown of collagen and promote the formation of wrinkles and irregular skin pigmentation. That is why it is especially important for “city dwellers” to thoroughly cleanse their skin in the evening.
Japanese researchers observed an interesting effect in a study: In their study, blue light from cell phones, tablets and PC screens appeared to damage the skin in a similar way to UV light. The study showed that blue light increased the formation of free radicals in the upper layer of the skin. Basically, free radicals are also responsible for premature skin aging.
With a few small changes to the settings of the “mobile end devices” you can reduce the radiation exposure enormously. Special blue light filters make screens and displays much gentler on the skin.
Check the settings to see whether your devices can be switched to “NightShift”, “Dark Mode” or “Night Mode”. You should also choose this setting during the day. The screen will then be a little more orange because the blue light component is filtered out.