Research news in brief

Dietary fibre lowers risk of diet-related diseases

Observational studies and clinical trials conducted over nearly 40 years reveal the health benefits of eating at least 25 g to 29 g or more of dietary fibre a day, according to a series of systematic reviews and meta-analyses published in The Lancet. The results suggest a 15–30% decrease in all-cause and cardiovascular-related mortality when comparing people who eat the highest amount of fibre with those who eat the least. Eating fibre-rich foods also reduced incidence of coronary heart disease, stroke, type 2 diabetes and colorectal cancer by 16–24%. Per 1000 participants, the impact translates into 13 fewer deaths and six fewer cases of coronary heart disease. In addition, a meta-analysis of clinical trials suggested that increasing fibre intakes was associated with lower bodyweight and cholesterol, compared with lower intakes. The study was commissioned by the World Health Organization to inform the development of new recommendations for optimal daily fibre intake and to determine which types of carbohydrate provide the best protection against non-communicable diseases (NCDs) and weight gain. The researchers included 185 observational studies containing data that relate to 135 million person years and 58 clinical trials involving 4635 adult participants. They focused on premature deaths from, and incidence of, coronary heart disease, cardiovascular disease and stroke, as well as incidence of type 2 diabetes, colorectal cancer and cancers associated with obesity: breast, endometrial, oesophageal and prostate cancer. The authors only included studies with healthy participants, so the findings cannot be applied to people with existing chronic diseases. For every 8 g increase of dietary fibre eaten per day, total deaths and incidences of coronary heart disease, type 2 diabetes, and colorectal cancer decreased by 5–27%. Protection against stroke and breast cancer also increased. Consuming 25 g to 29 g each day was adequate, but the data suggest that higher intakes of dietary fibre could provide even greater protection.

Hormone replacement therapy tablets associated with increased risk of blood clots

Hormone replacement therapy (HRT) tablets are associated with a higher risk of rare but serious blood clots (venous thromboembolism or VTE), finds a large study in The BMJ. No increased risk was found for HRT skin patches, gels or creams; yet, the majority of women choosing HRT continue to be prescribed oral preparations. Using two UK primary care databases (QResearch and CPRD), the researchers compared HRT prescription records of over 80 000 women aged 40–79 years who developed blood clots (cases) between 1998 and 2017, with those of over 390 000 women who did not (controls). Other relevant factors, such as lifestyle, family history of blood clots, and underlying conditions linked to blood clots, were taken into account. Most HRT tablets were found to be associated with increased VTE risk (nine extra cases per 10 000 women per year) compared with no HRT. Tablets containing equine oestrogen, including single and combined preparations, were consistently associated with higher risks than tablets containing synthetic oestrogen. Higher doses of oestrogen were also associated with higher VTE risk. However, no increased VTE risk was found for skin patches, gels and creams. This is an observational study and, as such, can’t establish cause, and the researchers point to some limitations that may have influenced the results. Nevertheless, they say this study “has provided a more detailed picture of the VTE risks for different HRT preparations and can help clinicians and women make treatment choices”.

What’s new online at the MJA

14 January Guideline summary: The Australasian Society of Clinical Immunology and Allergy infant feeding for allergy prevention guidelines
Joshi et al; doi: 10.5694/mja18.00493
Food allergy has been increasing in incidence worldwide, with rates in Australia the highest in the world … FREE ACCESS for one week

14 January Research letter: Nicotine and other potentially harmful compounds in “nicotine-free” e-cigarette liquids in Australia
Chivers et al; doi: 10.5694/mja18.00553
The nicotine levels in three e-liquids were comparable with those of low dose nicotine e-liquids … FREE ACCESS permanently

14 January Podcast: Professor Anne Roche, Director of the National Centre for Education and Training on Addiction, at Flinders University … FREE ACCESS permanently