Some dietary factors may protect against rheumatoid arthritis onset, study finds

9th December 2024

Eating higher amounts of foods such as oily fish, cereals, vegetables and the nutrient vitamin D, as well as moderating alcohol intake, could reduce the risk of developing rheumatoid arthritis, a new study has revealed.

Researchers at the University of Leeds examined 32 different food groups, drinks and nutrients and determined the associated risks of developing rheumatoid arthritis. They found that some food groups could help reduce rheumatoid arthritis onset, while others, such as tea and coffee, were associated with an increased risk of developing the disease.

The findings are published in the journal Nutrients and highlight how controlling certain dietary factors could protect some people from developing the disease.

The researchers conducted a meta-analysis review of 30 studies undertaken between 2000 and 2024 involving almost 10,000 people. A total of 12 studies were conducted in Europe, 15 in America and three in Asia.

A higher intake of fruits and cereals was associated with a lower risk of rheumatoid arthritis and showed potential protective effects against its development. The association was linear, and consuming a greater amount continued to offer an increase in protection.

Vegetables, oily fish and vitamin D, followed a non-linear association. Increased consumption initially led to led to potential protective effects against rheumatoid arthritis development, but the effect plateaued beyond this level.

Drinking small amounts of alcohol (around two units per week) had a protective effect against rheumatoid arthritis, but at higher consumption levels, the risk of developing the disease increased. Excess alcohol intake negated the benefits seen at lower levels, and the protective effect disappeared at around consumption levels of 7.5 units per week.

Tea and coffee were associated with an increased risk of developing the disease. Each additional cup of tea consumed daily was associated with a 4% increase in risk. However, the baseline risk from tea was low, and the researchers stressed the many health benefits of tea. There was no evidence of an association between sugar-sweetened soda and rheumatoid arthritis risk.

Yuanyuan Dong, a PhD student at the School of Food Science and Nutrition at the University of Leeds, said: ‘Rheumatoid arthritis is a typical multifactorial disease, driven by both genetic and environmental factors. These findings offer a deeper understanding of how diet can impact rheumatoid arthritis risk and suggest potential dietary modifications for disease prevention and management.’

The researchers suggested that dietary factors contribute to the risk of rheumatoid arthritis by increasing inflammation and affecting the immune system. However, stressing the ‘one-size-fits-all’ advice to follow a generally healthy diet is not helpful for people with autoimmune diseases, and the research highlights the need for a more personalised approach.

Study co-author and PhD supervisor Janet Cade, professor of nutritional epidemiology at the University of Leeds, said: ‘The results are promising, showing that by eating higher amounts of foods like oily fish, cereals, vegetables and the nutrient vitamin D, people may be able to lower their chances of developing this painful and debilitating condition.’

She added: ‘More research will help us pinpoint exactly why these foods have the effect we have observed and develop tailored nutritional advice for people living with rheumatoid arthritis and other autoimmune diseases.’

A version of this article was originally published by our sister publication Nursing in Practice.

To what extent does eating more nuts help to slow cognitive decline?

27th July 2023

A higher intake of nuts in older adults at risk of cognitive decline could help to slow the decrease in cognitive performance, although the evidence to date is far from clear. Clinical writer Rod Tucker takes a closer look.

The term ‘dementia’ embraces a number of diseases that affect memory, thinking and the ability to perform daily activities. In short, dementia represents the loss of cognitive health, which is key feature of healthy aging.

Unfortunately, the level of dementia appears to be on the rise, becoming a growing and global problem. According to the World Health Organization, there are currently an estimated 55 million people living with dementia worldwide, and this figure is expected to rise in the coming years. Moreover, dementia the seventh leading cause of death and one of the major causes of disability and dependency among older people globally.

There are no known cures for dementia, but efforts have been directed at a range of potential modifiable risk factors, outlined in a 2020 Lancet review. One such factor is diet – particularly the Mediterranean diet, which consists of a high intake of vegetables, legumes, fruits, nuts, cereals and olive oil. But is there evidence to support a higher intake of the individual components in the Mediterranean diet as a means of reducing the risk of cognitive decline?

One constituent that has gained interest in recent years as a strategy to modify cognitive decline, is a higher intake of nuts, but the strength of the evidence supporting this proposition requires more analysis.

Nut intake and cognitive decline

Tree nuts and peanuts (henceforth, nuts) are nutrient-dense foods with a myriad of biologically active ingredients such as unsaturated fatty acids and high-quality vegetable protein, combined with an array of vitamins and beneficial minerals, dietary fibre, phenolic compounds and phytosterols. Peanuts, though botanically classified as legumes rather than nuts, do contain a similar nutrient profile as tree nuts and to all intents and purposes can be considered a nut.

To date, there is compelling evidence for the cardiovascular protective effect of a higher nut intake, largely through an improvement in the lipid profile. For example, it is recognised that a daily intake of small amounts of walnuts lowers LDL cholesterol.

Despite the cardiovascular benefits, much less is known about whether the intake of nuts impacts on brain health, and in particular, if this reduces the risk of cognitive decline. Nevertheless, nuts are likely to have an important effect on the brain as recognised by a recent systematic review on depression.

The review, which included 10 studies with over 60,000 participants, concluded that a higher nut consumption could be associated with a lower risk of depression, fewer depressive symptoms and better mood state in the general population.

In relation to cognitive health, another recent review suggested that while the available evidence was limited and inconclusive, there was likely to be a possible role for nuts for the maintenance of cognitive health and the prevention of cognitive decline, particularly in older adults and those at higher risk.

Randomised trial evidence

With supportive data from observational studies, the real test of efficacy can only really be determined from randomised, interventional, controlled trials. So, how does this evidence stack up?

Unfortunately, findings have been somewhat mixed. For instance, the PREDIMED-NAVARRA randomised trial explored the impact of a Mediterranean diet on cognitive function. Some 522 participants at high vascular risk were assessed and compared a Mediterranean diet supplemented with either extra-virgin olive oil or mixed nuts versus a low-fat control diet. Interestingly, the study found that both Mediterranean diets appeared to improve cognition compared with a low-fat diet.

In contrast, the MedLey Study, which used a Mediterranean diet in older adults compared to a control diet, failed to detect any effect of a Mediterranean diet on cognitive function among healthy older adults. Similarly, a trial in which healthy older adults were randomised to receive an additional intake of almonds found no improvement in cognitive function. A second interventional trial, this time using walnuts, while showing no effect on cognition in healthy elders, did observe that that walnuts might delay cognitive decline in subgroups at higher risk.

The most recent study to examine the effect of consuming nuts on cognitive function, published in June 2023, looked at the two-year impact on cognitive performance in 6,630 adults with a mean age of 65 years who were deemed at risk of cognitive decline.

Nut consumption was categorised as less than one serving per week, one to three servings, between three and seven servings or more than seven serving per week, with a serving defined as 30g. Although the study was prospective in nature, and therefore subject to several recognised limitations, the researchers did see a benefit from increased nut consumption.

Using those who consumed less than one serving of nuts per week as a comparator, the results showed that eating between three and seven servings per week or more than seven portions both demonstrated more favourable changes in general cognitive performance. Although not the main focus of the study, the researchers also found a potential synergistic interaction between nut consumption and depression. In other words, participants with depressive symptoms at baseline tended to benefit more from the consumption of nuts than those without depression.

There seems to be plenty of observational evidence that nut consumption may help to delay the onset of cognitive decline, as randomised interventional studies have not provided consistent findings. In addition, no studies have specifically addressed the effect of eating nuts on hard clinical outcomes such as the development of dementia or Alzheimer’s disease.

While the latest prospective study does suggest a possible cognitive benefit, there is an urgent need for more randomised, interventional trials before recommending increased consumption of nuts to either delay cognitive decline or prevent the onset or progression of cognitive impairment and dementia.

But given a possible link between the cardiovascular and dementia biochemical pathways, it remains plausible that inclusion of more nuts into an individual’s diet might not only improve their cardiovascular health but could help to ameliorate cognitive decline.