Diet and eczema

This page contains two diet-related articles from our magazine, Exchange.

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Is vitamin D the answer?

Can probiotics help prevent eczema?

Is vitamin D the answer?

This is an Ask the Expert Q&A with Julie Van Onselen, Dermatology Nurse Adviser to NES, which was published in Exchange 185, September 2022.

Q.: I’m always looking for ways to treat my eczema holistically. I recently read that vitamin D can help improve it. The sun irritates my skin, so I try to stay out of the sunlight – should I start taking supplements?

Julie Van Onselen says: Vitamin D is essential for healthy bones and teeth and supports good immune function as it regulates the immune system (and atopic eczema is an autoimmune condition). Other than supplements, vitamin D is obtained from sunlight and foods.

There has been some research into whether low levels of vitamin D trigger the development of eczema, and if taking supplements can improve symptoms. A key clinical review in 2015 proposed a link between eczema and lower levels of vitamin D, and found that vitamin D helped protect the skin barrier and suppress inflammation.

A 2018 systemic review found that children under 18 with low vitamin D levels had more severe eczema, with 67% seeing improvements after taking vitamin D supplements.

Recent research published in the British Journal of Dermatology revealed that babies had a lower risk of developing atopic eczema in their first year if their mothers took 25mcg of vitamin D daily from 14 weeks of pregnancy until delivery. However, overall, there is not enough evidence that vitamin D affects the development of atopic eczema.

Nevertheless, supplements may be beneficial. Only a very small amount of sun exposure is required to build vitamin D levels, but the UK climate provides enough sunlight only six months of the year. For that reason, NHS guidelines recommend that everyone in the UK should consider taking a vitamin D supplement from October to April, and that those at high risk of not getting enough, including all children aged 0–4 (except for babies drinking more than 500ml of formula milk every day) should take it every day, all year long.

The people mentioned who are at high risk of vitamin D deficiency include infants, older people and those with darker skin tones, and those with some health conditions, such as Crohn’s, ulcerative colitis and coeliac disease. It also includes people who don’t expose their skin to sunlight (for example, because it’s an irritant for their eczema).

For people whose levels are low, vitamin D is available on prescription. However, measuring this requires a blood test. This is not routinely offered to people with eczema, but you can ask for it to be added to any other blood tests you have. Even if your levels are normal, taking a daily supplement of 15–20mcg of vitamin D2 (or D3, for vegans) is beneficial during the colder months, for general health. Take it with a meal, as vitamin D is fat soluble, and don’t exceed the recommended daily dose, as this can be harmful.

Can probiotics help prevent eczema?

Probiotics are gaining popularity, but could they be a game-changer for people with eczema? Exchange talks to Professor Carsten Flohr from St John’s Institute of Dermatology at Guy’s and St Thomas’ Hospitals. This article was published in Exchange 182, December 2021.

What are probiotics?

Probiotics are live microorganisms (bacteria or fungi) that are consumed or applied to the skin to improve health. They can be found in a range of products, from live yogurt and other fermented foods, to dietary supplements.

Probiotics seem to be the ‘new best thing’ – but can they make a difference to someone with eczema?

The answer is ‘yes’ – but the relationship between probiotics and eczema is complex. The research shows clearly that probiotics cannot cure eczema once it’s developed, but they can help prevent eczema from developing in babies that are predisposed to eczema.

So we’re not talking about a miracle cure?

Sadly, no. We have enough evidence to show that giving probiotics to people with eczema definitely won’t significantly improve it. Once the inflammation is triggered and the itch-scratch cycle has started (in other words, once the baby has symptoms of eczema) it’s too late.

So, if you or your child already has eczema, there isn’t much point in taking probiotics to make the eczema better. There may be other health benefits, of course, but it wouldn’t be effective directly in treating the eczema.

But you say probiotics can prevent eczema?

Yes. In babies with a high risk of eczema (for example, if the mother has it) and where the itch-scratch cycle isn’t yet triggered, studies have found up to 50% fewer cases of eczema in babies following probiotic treatment. For this to work, the mother would have to take probiotics during the last trimester of pregnancy, and ideally the baby would receive supplements as well.

It is important to be aware, though, that the research studies are a mixed bag. The two main types of probiotic that impact on the gut – lactobacillus and bifidobacterium – are available in many different preparations, and the studies used various combinations of these. So it’s very difficult to say to someone, hand on heart, ‘This is the best product to recommend to you.’ The best ones are probably those refrigerated in health food shops, but they can be expensive and even with these we don’t have complete certainty.

Can probiotics be used directly on the skin?

There’s quite a bit of research into how the skin’s immune system talks to bacteria such as Staphylococcus aureus (Staph aureus) – the main bacterium that colonise skin in people with eczema, causing flares, infections and hospital stays. Scientists are testing whether other bacteria have a protective effect, ‘fighting off’ Staph aureus. These other bacteria include Staph epidermidis and Proprionibacterium acnes, which like areas of the skin such as the face and back.

The skin is also home to fungi and viruses. Fungi prefer moist areas, such as sweaty feet and under the arms. Some fungal species are quite common, like Malassezia purpura, which can secondarily infect eczema, but they probably don’t play such an important role.

In another area of research, colleagues in the United States identified bacteria in people who had eczema alongside unhealthy levels of Staph aureus. For each person, they isolated the strains of bacteria that would inhibit the growth of Staph aureus, colonised these strains in large numbers, and then put them into cream, which they applied to the person’s skin. That seemed to help get rid of the Staph aureus. But because each batch of bacteria was returned to the original person it came from, this was a very personalized treatment approach that could not be scaled up to manufacturing level.

Another environment with a complex microbiome is spa water. In Germany, health insurance companies pay for people to go to spas to recover from conditions including severe eczema, so researchers investigated the properties of one particular bacterium found in spa water: Vitreoscilla filiformis.

The dermatologists isolated this bacterium from spa water and put it into a cream for people with mild eczema. This did result in reduced itching, but that research was in 2014 and there haven’t yet been further studies using a topical probiotic preparation with this spa water bacterium.

Could probiotics reduce the risk of flares by boosting your immune system more generally?

We know that people who have a less diverse gut flora as babies are more likely to develop eczema. There’s no doubt about that – the results have been replicated many times. This is why, as we saw earlier, probiotic supplements can ensure a more diverse microflora in early life and, in turn, stimulate the immune system to protect from inflammation.

But it’s very complicated because there are many other factors – such as filaggrin gene mutations, which predispose people to a disrupted skin barrier and dry skin – and environmental factors such as water hardness or treatment with antibiotics. All these will have a detrimental effect on the skin, the gut microbiome and, potentially, the skin microbiome, too.

Are there any dietary choices that could help?

Our team has shown – in the biggest breastfeeding intervention study ever conducted, among more than 16,000 mothers and their children – that promoting breastfeeding can help prevent eczema into adolescence. However, and importantly, exclusive breastfeeding is not required.

Early weaning also helps prevent food allergies. Babies who are fed foods that most commonly trigger allergies – cows’ milk, egg, peanut, sesame, cod and wheat – from three months, alongside breastfeeding, are significantly less likely to develop allergies. It’s about stimulating the immune system, teaching it what is OK to eat. Most allergies are developed through the skin rather than the mouth. When the foods are ingested, the immune system learns that they are safe.

If a child has early onset eczema, they are particularly vulnerable to allergies because immune cells are already working overtime because of the eczema. The immune system actually reaches up to the top of the skin with finger-like tentacles called dendritic cells (dendron comes from the Greek word for tree). It’s been shown that these cells can actually sense the environments directly from inside the skin and can detect tiny particles of food protein in house dust on the skin. That’s how a child becomes allergic to foods.

This is just another example of the importance of our gut and skin biome and why it helps to have a broad mix of skin flora – including probiotics – to set babies up with a strong immune system. I suspect the same applies to the skin, but so far, we haven’t got enough data to say this for certain.

It sounds as if there’s lots of research going on in this area.

Yes – it’s really fascinating to understand better how Staph aureus causes flares. That’s one of my research group’s areas of interest. At this stage, we’re still trying to understand, at the molecular level, how the bacteria make the eczema so much worse. We’ve known the link for decades, but we don’t exactly know how it happens, and this might be quite useful in terms of new therapies for people who are particularly prone to skin infections – perhaps because of imbalances in their skin biome.

If you’re having a baby: precautions to take

If you’re pregnant and your baby is at higher risk of developing eczema – for example, if you or your partner has the filaggrin gene mutation – you may want to consider taking probiotics during pregnancy as a precaution, as it may help.

Once your baby is born, consider giving them probiotics for the first few months of life and introducing a wide range of foods from three months, alongside their milk, rather than waiting till the standard NHS recommended period of six months.

Professor Carsten Flohr is Consultant Dermatologist and Research and Development Lead at St John’s Institute of Dermatology, Guy’s and St Thomas’ NHS Foundation Trust. He also holds the Chair in Dermatology and Population Health Science at King’s College London and is President of the British Society for Paediatric Dermatology.