Medical Bulletin 23/ May/ 2024

A recent study published in The Journal of Nutrition found that potato consumption moderately reduces the risk of all-cause mortality and cardiovascular disease-specific mortality in adults.

Potatoes are a staple food in many traditional diets, making them one of the most commonly consumed vegetables worldwide. They are a rich source of potassium, vitamin C, dietary fibers, and numerous bioactive compounds, all of which are essential nutrients that offer cardiovascular health benefits.

However, despite these nutritional advantages, potatoes are often not recommended as a vegetable due to their high starch content. Their high glycemic index has been linked to an increased risk of cardiometabolic diseases.

The latest Nordic Nutrition Recommendations suggest including potatoes in regular diets, but they do not provide specific guidelines due to insufficient evidence. Additionally, past studies examining the relationship between potato consumption and cardiovascular disease-specific mortality have yielded inconsistent results.

In the study, a total of 77,297 adults aged 18 to 64 were enrolled. Participants underwent three cardiovascular health screenings. During each screening, semi-quantitative food frequency questionnaires were used to gather dietary information, which helped calculate weekly potato intake and daily cumulative mean intake.

Information on all-cause and cardiovascular disease-specific mortality was obtained from the Norwegian Cause of Death. Appropriate statistical analyses were conducted to determine the association between potato intake and the risk of all-cause and cardiovascular mortality.

The results showed that men consumed more potatoes than women. Those with higher potato intake were often current smokers, more physically active, and less likely to be obese. Lower potato intake was linked to higher diabetes prevalence.

Participants consuming 14 or more potatoes weekly had a lower risk of all-cause mortality compared to those consuming six or fewer. Each 100 grams per day increase in potato intake reduced the risk of all-cause and cardiovascular mortality by 4%. The significant link between potato intake and reduced cardiovascular mortality was seen only in men.

The findings indicated a modest inverse association between long-term habitual potato intake and the risk of all-cause and cardiovascular disease-specific mortality.

Previous studies that reported either an adverse or no impact on all-cause mortality risk often grouped processed potato products with whole potatoes. Notably, specific methods of preparation significantly influence the nutritional profile of potatoes.

Reference: Arnesen, E. K., Laake, I., Carlsen, M. H., et al. (2024). Potato consumption and all-cause and cardiovascular disease mortality – a long-term follow-up of a Norwegian cohort. The Journal of Nutrition. doi:10.1016/j.tjnut.2024.05.011

According to a study published in BMJ Medicine, regular use of fish oil supplements might increase the risk of first-time heart disease and stroke among those in good cardiovascular health but may slow the progression of existing poor cardiovascular health and lower the risk of death.

Cardiovascular disease is the leading cause of death worldwide, accounting for about one-sixth of overall mortality.

Fish oil, a rich source of omega-3 fatty acids, containing eicosapentaenoic acid and docosahexaenoic acid, has been recommended as a dietary measure to prevent cardiovascular disease. Although some epidemiological and clinical studies have assessed the effect of omega 3 fatty acids or fish oil on cardiovascular disease and its risk factors, the findings are inconsistent.

In the study, researchers analysed data from 415,737 UK Biobank participants, aged 40-69, to estimate the association between fish oil supplements and the risk of new cases of atrial fibrillation, heart attack, stroke, heart failure, and death. They assessed the progression from good heart health to atrial fibrillation, major cardiovascular events, and death. Their health was tracked using medical records until March 2021 or until death.

The results showed that nearly a third (31.5%) of the participants regularly used fish oil supplements. Over an average monitoring period of nearly 12 years, 18,367 developed atrial fibrillation, 22,636 experienced a heart attack, stroke, or heart failure, and 22,140 died.

Regular fish oil supplement use was linked to a 13% higher risk of atrial fibrillation and a 5% higher risk of stroke for those with no known cardiovascular disease at the start. Conversely, for those with cardiovascular disease, fish oil supplements were associated with a 15% lower risk of heart attack following atrial fibrillation and a 9% lower risk of death following heart failure.

The findings revealed that regular use of fish oil supplements and the risk of transitioning from good health to heart attack, stroke, or heart failure was 6% higher in women and 6% higher in non-smokers. And the protective effect of these supplements on the transition from good health to death was greater in men (7% lower risk) and older participants (11% lower risk).

“Regular use of fish oil supplements might have different roles in the progression of cardiovascular disease. Further studies are needed to determine the precise mechanisms for the development and prognosis of cardiovascular disease events with regular use of fish oil supplements,” said the study authors.

Reference: Chen G, Qian Z(, Zhang J, et al.; Regular use of fish oil supplements and course of cardiovascular diseases: prospective cohort study; BMJ Medicine 2024;3:e000451. doi:10.1136/bmjmed-2022-000451

Researchers at the Universities of Birmingham and Bath have found that a bout of exercise increased the number of anti-cancer immune cells – called natural killer cells – and that these cells were around twice as effective at killing cancer cells in ‘ex vivo’ tests carried out on blood samples from patients.

The study, published in the journal Brain Behavior and Immunity, showed that the number of cancer cells present in blood samples transiently increased immediately after exercise – making them more susceptible to attack by natural killer cells and the antibody therapy.

Previous research has shown that during an individual bout of moderate to vigorous intensity aerobic exercise in healthy humans, immune cell frequency in peripheral blood increases profoundly.

Regular exercise may increase the body's immune response against cancer by increasing the number of anti-cancer immune cells, specifically natural killer (NK) cells. These specialized immune cells play a crucial role in identifying and eliminating cancerous cells within the body.

Additionally, exercise has been found to improve the overall function of the immune system, creating a more hostile environment for tumor growth and metastasis.

In the study, researchers worked with 20 individuals aged between 45 and 82 who had been diagnosed with chronic lymphocytic leukemia but had not yet undergone treatment. These participants engaged in a 30-minute session of moderate-to-vigorous intensity cycling.

Blood samples were collected before and immediately after the exercise session, with a third sample taken an hour later. The researchers then assessed the number of natural killer cells present in the blood samples at each time point under 'ex vivo' conditions.

Additionally, they evaluated the ability of these natural killer cells to target and kill cancer cells, both with and without the presence of Rituximab.

They found the number of natural killer cells increased by 254% after exercise and that in the blood samples taken after exercise, there were 67% more cancer cells compared to blood before exercise.

Further, the team isolated natural killer cells and put them in close contact with cancer cells for 2 hours ‘ex vivo’ with and without the antibody therapy Rituximab and discovered that when Rituximab was also present in the blood sample, natural killer cells were just over twice as effective in killing the cancer cells in the samples collected immediately after exercise compared to before.

“Cancer cells often try to ‘hide’ in the body but it seems that exercise works to move them out into the bloodstream, where they are vulnerable to the antibody therapy and the killing capabilities of natural killer cells. This study underscores the beneficial role of exercise in cancer treatment, suggesting its utility before, during, and after therapy. Physical activity has been shown to enhance coping mechanisms during treatment, support recovery, and boost mental well-being among cancer patients. Additionally, the results could also have the potential for patients who have finished their treatment for leukaemia and are in a monitoring phase in case cancer cells re-appear,” said the study authors.

Reference: Harrison D. Collier-Bain, et al.; A single bout of vigorous intensity exercise enhances the efficacy of rituximab against human chronic lymphocytic leukaemia B-cells ex vivo; Brain, Behavior, and Immunity; 2024; https://doi.org/10.1016/j.bbi.2024.03.023.