Despite how many women it affects, endometriosis – and its treatment – has long been haunted by a lack of funding, understanding and awareness. The fact that it still takes an average of eight years and 10 months for women to receive a diagnosis (a figure that has significantly worsened over the last three years), is evidence enough that things urgently need to change.

However, one good piece of news is that research into endometriosis – including its causes and potential treatment options – is on the rise. And over the last year in particular, there’s been a surge in research looking into the role that the gut microbiome and diet could play in the disease.

One such study, published last week, pulled into question the commonly held belief that there’s a link between zinc deficiency and endometriosis. A trace mineral involved in bodily functions including hormone regulation and immune health, experts previously believed that women who had low levels of zinc – whether due to a nutrient-poor diet or medical issues that make it hard to absorb zinc from their food – were at a higher risk of developing endometriosis.  

However, the new study, published in the journal BMC Public Health, suggests the opposite may be true. Based on secondary analysis of data from the National Health And Nutrition Examination Survey, which was conducted between 1999 and 2006 and based on women aged 20–54, the study found that women who consumed more than 14mg of zinc daily appeared to have a 60% higher risk of endometriosis compared to those who consumed 8mg or less.

Zinc is found in a wide range of foods including poultry, beef, legumes, seeds and seafood, so most people get a good amount from their diet. Some of us also take zinc in supplement form, whether in an isolated supplement to boost our immune system or in a multivitamin (zinc is often combined with vitamin C to increase absorption, for example).

But what does this study mean for the prevention of endometriosis? Should women be watching their zinc intake? And if so, how can we do that? We asked the experts to explain. 

While this study establishes a correlation between a higher zinc intake and endometriosis, it does not prove that it can cause endometriosis. The findings are observational, ie they simply look at the bigger picture rather than what’s happening inside the body.

In fact, according to nutrition experts, several key methodological issues limit the lessons we can learn from this research.

Nutritional therapist Alexa Mullane says the amount of data involved is one such issue. “The participants in the study only undertook two 24-hour dietary recall interviews, meaning that only two days’ worth of food was analysed,” she explains. “This means the study didn’t account for anything else that the women had eaten in the weeks, months or years before the study.”

Steph Baker, a registered nutritionist and in-house nutritionist consultant at Purolabs, also flags the method used to collect the data. “The study is based on a secondary analysis of surveys taken, with a focus on dietary recall to calculate how much zinc participants ingested,” she says. “Studies have shown that dietary recall isn’t the most reliable way for us to track dietary intake, with people commonly over or underestimating their food intake.” 

With all of this in mind, it’s worth taking the results of this study with a big pinch of salt. Previous studies have shown zinc to be crucial for our hormone and reproductive health, so cutting it out of your diet or reducing your intake could do more harm than good for women.

However, what this study does do is unearth a potential link between high zinc intake and endometriosis and highlight the need for more research to be carried out.

For now, however, it’s best to stick to NHS recommended guidelines – for women, that’s 7.5mg a day. “I recommend that endometriosis sufferers continue to include zinc in their daily diet,” Baker adds. “Be sure to include zinc-rich foods like seafood, pumpkin seeds and legumes and stick to the government-recommended dietary guidelines until further studies are carried out.” 

Images: Getty