Nutrition and Rheumatoid Arthritis Onset: A Prospective Analysis Using the UK Biobank,2022, Camillia Barbero Mazzucca et al

Abstract

Rheumatoid arthritis (RA) is a chronic inflammatory disease that affects the joints. The multifactorial etiopathogenesis of RA has been heavily investigated, but is still only partially understood. Diet can represent both a risk factor and a protective factor, based on some evidence that suggests specific properties of certain foods and their ability to increase/reduce inflammation.

To date, the studies done on this topic provide discordant results and are heterogeneous in terms of design and cohort size. In this work, we investigated for the first time the relationship between nutrition and the risk of RA onset using a sample size of about half a million subjects from one of the largest publicly available biobanks that is the UK biobank.

Results showed that oily fish, alcohol, coffee and breakfast cereals have protective roles in RA; whereas, tea can increase the risk of RA. In conclusion, the obtained results confirm that diet plays key roles in RA, either by promoting or by preventing RA onset and development.

Future research should focus on unravelling the effects of dietary habits on immune-mediated diseases to establish better preventive strategies.

https://www.mdpi.com/2072-6643/14/8/1554/htm

@Jonathan Edwards this sounds a bit odd. Are the rates of RA higher in the UK b/c of tea drinking?

 

Biobank cohorts are probably quite useful for genetic studies but for this sort of environmental factor study one would need to know that there were no various confounding associations.
The lower rates of RA reported in Wales and Scotland versus England is odd for a start.

The association with smoking is confirmed though.

Not many of the factors they quote show dose effects, beyond smoking. That looks problematic. There ought to be dose effects.

 

The (sort of) hypothesis they seem to be testing is based on global RA rates - simplistic comparisons between high RA populations (USA) and low RA populations (SE Asia) hence the 'Western Diet' model; there are all sorts of confounds in this approach; I guess one can say this is all very interesting but still may not tell us much. I missed any mention of higher northern latitude increase in prevalence which I think is now well attested, Geographical factors in rheumatoid arthritis . Data on global prevalence = Global, regional and national burden of rheumatoid arthritis 1990–2017: a systematic analysis of the Global Burden of Disease study 2017 full article at SciHub https://sci-hub.se/10.1136/annrheumdis-2019-215920

 

Scotland and Wales - off top of my head in the wee small hours ( so may be complete rubbish)

Celtic genes ? Impacted in other diseases - could be protective for others - or perhaps there is an exclusionary effect - if you have disease A you don't get disease B
Lower life expectancy ( if you are already dead it's hard to diagnose )
Air pollution -less population in cities than England ( could be similar mechanism to smoking )

 

The most likely explanation to me is that there still aren't that many rheumatologists in rural Scotland and Wales so fewer people get diagnosed. A high proportion of RA is quite mild and very easily missed by GPs following dumb protocols.