No proof? EUFIC questions study suggesting link between vegetarian diets and hip fractures

26 Aug 2022 --- The European Food Information Council (EUFIC) has flagged limitations to a study published by the BMC Journal that links an increased hip fracture risk in women with vegetarian diets. The council slams the study as it “does not prove that vegetarian diets are the cause of hip fracture,” while arguing that it lacks consideration of ethnicity and the evolution of nutritious vegetarian foods over the past 20 years.

The observational study was carried out over 22 years and included 26,318 women logging their dietary patterns. It concluded that women following a vegetarian diet have a 33% higher risk for hip fracture later in life than regular meat eaters.

NutritionInsight speaks to the EUFIC and the study’s lead researcher on the limitations and implications of the discussion.

“These types of studies are very complex, and overall the study quality was good. However, the authors did not consider other factors that could potentially affect the risk of hip fracture – such as supplemental sources of specific nutrients and circulating vitamin D concentrations – due to a lack of data,” notes Laura Bosman, content producer at EUFIC.

Future research neededThe study did not include several groups of the society, therefore cannot be applied to the larger population.
Bosman explains that while this is a limitation of the study, future research must first investigate these factors on hip fracture risk in vegetarians to better understand their role in the hip fracture association. 

“With our article, we wanted to make sure that the findings are interpreted correctly and that people who want to follow a vegetarian or vegan diet should not be discouraged to do so,” she notes.

“The wording in the article from EUFIC is ‘The study does not prove that vegetarian diets are the cause of hip fracture.’ This is an important limitation to be aware of,” highlights James Webster, lead researcher for the study and postgraduate researcher at the University of Leeds.

“We did show that vegetarians were at a greater risk of hip fracture than meat-eaters in middle-aged women who live in the UK,” he notes. “Still, because this is an observational study, we cannot show causality.”

“This is because, unlike randomized controlled trials, we could not account for unmeasured factors that might influence the risk of hip fracture and could differ between diet groups, for example genetic predisposition to hip fracture,” Webster notes.

Evolution of vegetarian foodThe food evolution has taken rapid pace in the last 20 years, as demand and environmental awareness increased.
Due to the increased popularity of vegetarian and plant-based alternatives, the council stresses that nutritional intake from vegetarian diets in recent years has changed. Therefore, it claims it is difficult to conclude that the study applies to modern-day vegetarians. 

“We could not account for changes in the food industry over time because this was not measured. The diet data used to classify women into diet groups was collected around 20 years ago,” says Webster. 

“A follow-up dietary questionnaire was completed by a small subset of the women included in the study a few years after recruitment, but there was no subsequent questionnaire. I also imagine that measuring the development of the food industry over 20 years would take several studies to do in their own right, and wasn’t the focus of our study.” 

Additionally, the council flags that the study only included white European women and therefore cannot be applied to a larger population, which was acknowledged by the authors. 

There was no differentiation between vegetarian and vegan women, and only 130 vegans were participating in the study, accounting for 0.5% of the population, the EUFIC underscores.

“Our results apply at the population level, not at the individual level where variation in diet and other factors contribute to an individual’s overall risk of hip fracture,” Webster concludes. 

Vegetarian diets
The EUFIC mentions that vegetarian diets are suitable for all genders and through all stages in life, including pregnancy, lactation and infancy, as long as all nutritional needs are met, like with any other dietary pattern.

“If not well balanced, several key nutrients may be deficient in vegetarian and vegan diets leading to absent or poor absorption from the gut. These include high-quality protein, long-chain omega 3 fatty acids, iron, zinc, calcium and vitamins D and B12. The lack of the minerals and vitamins may lead to anemia, poor bone health, or neurological damage,” Bosman notes. 

“However, when a vegetarian diet is appropriately planned, including a variety of different (fortified) foods and dietary supplements where necessary, it can be nutritionally adequate. Besides, it can promote health by lowering the risk of many major chronic diseases, such as cardiovascular diseases, type 2 diabetes, and certain cancers. It is generally more environmentally friendly than an omnivorous diet,” she concludes.

Recent studies have shown that vegetarian diets may be more efficient for weight management and insulin sensitivity and have positive effects on preventing cardiovascular diseases.

By Beatrice Wihlander