By: Talking Nutrition Editors
With 9% of the world’s population over the age of 65 and this figure expected to double by 20501, the world’s ageing population is growing rapidly. This is putting an increased focus on ways to support the health and quality of life of the elderly, particularly when it comes to strengthening their immunity. As we age, our immune systems are weakened, making this population group increasingly susceptible to morbidity and mortality from infections and disease. The awareness of the dysregulation of the immune and inflammatory response – known as immunosenescence and inflammaging – has become particularly heightened during the global COVID-19 pandemic. But what causes this increased vulnerability in the elderly?
As Dr. Meydani explained during the symposium, many factors contribute to the weakening of the innate and adaptive immune system as we age, including a decline in T cell-mediated function – the part of the immune system that fights microbial infections – and an increase in inflammatory responses. As the ability to proliferate and produce key cytokines is impaired with ageing – combined with a higher level of inflammatory cytokines – older adults are more susceptible to infections and autoimmune diseases, as we have seen throughout the COVID-19 pandemic.
Both Dr. Meydani and Dr. Laviano stressed the impact of nutritional status on immune function in the elderly. Many older populations have nutritional challenges exhibited as undernutrition (micronutrient deficiencies) and overnutrition (obesity). While anorexia of aging – the loss of appetite and reduced food intake common in older people – is a key cause of undernutrition in the elderly, the increasing prevalence of obesity in older adults means the micronutrient deficiencies may develop unnoticed, leading to diagnoses of malnutrition being missed. In the US for example, where 50% of older adults are overweight or obese, many elderly people have compromised micronutrient status/intake of Vitamin D, vitamin E, B12, B6, folate, zinc, selenium, iron and calcium.
Both undernutrition and overnutrition can impair T cell-mediated response and increase uncontrolled inflammation, increasing susceptibility, morbidity and mortality from infections. Dr. Meydani highlighted one animal model study that demonstrated how obesity can impair T cell-mediated function and result in a much higher level of inflammatory cytokines compared to non-obese mice. Importantly, a healthy diet has been shown to reverse this trend. Supplementing obese mice with fruit and vegetables has been shown to improve the dysregulation of immune response and reverse trend lower T cell-mediated proliferation that is linked with obesity.2
Prevention and correction of malnutrition through nutritional management and micronutrient supplementation play a critical role in supporting immune health in the elderly. Evidencing the importance of nutritional management in elderly patients, Dr. Meydani highlighted the impact of vitamin E and zinc supplementation on preventing infection, reducing medication consumption and the duration of infections.
One remarkable study focused on a nutritional intervention with vitamin E in nursing homes delivered an incredible outcome for immune health. By supplementing residents with 200 IU of vitamin E for one year, the risk of all respiratory infections was reduced by 35%, with the risk of upper respiratory infections reduced by 38% and the common cold by 37%.3
Another insightful study discussed by Dr. Meydani revealed the important role of zinc in supporting immune health and preventing infections in the elderly. Supplementing zinc-deficient, elderly nursing home residents with 30mg of zinc daily was shown to increase serum zinc levels and improve T cell function.4 Additional evidence shows that 45mg of zinc supplementation over one year led to lower incidences of upper respiratory infections and the common cold in elderly people.5
Whether through anorexia of aging or decreased energy requirements, we know that older people are less likely to be able to meet the RDA for micronutrients through their diet alone. We also know that the decline in T cell-mediated function in elderly people is also associated with the body’s response to vaccines. However, our experts explained how a healthy diet, combined with micronutrient supplementation, can improve T cell-mediated function and therefore vaccine efficacy in elderly populations.
Dr. Laviano described that introducing achievable dietary goals – potentially as part of nutritional screening - can be linked with immune function, sharing a study that showed how increasing fruit and vegetable intake improves Pneumovax II vaccination antibody response in older people.
A number of studies have also revealed that vitamin E in particular may support improved response to vaccines. By supplementing healthy elder adults with different levels of vitamin E for four and a half months, then reviewing their response to the hepatitis B vaccine – a T cell dependent vaccine that is often impaired in older adults – a 200 IU of vitamin E was shown to significantly improve response to the vaccine.6
The COVID-19 pandemic has demonstrated the importance of the role of optimal nutritional management to support patients and improve recovery.
Since the beginning of the pandemic, our understanding of the disease has improved and we know that the immune system is an important factor not only in pathogenesis, but also the severity of COVID-19. Many of the risk factors for negative outcomes from the disease are associated with either changes in body composition or changes in dietary intake. Older adults are particularly vulnerable, with the impact of sarcopenia, higher incidences of NCDs and poor nutrient intake associated with higher risk of hospitalization. However, the prevention of micronutrient deficits could help contribute to an efficient immune response to disease. In China, for example, studies have shown a clear correlation between selenium status in city populations and COVID-19 outcomes, with a higher level of selenium linked to a higher cure rate.7
Recent studies around vitamin D – which contributes to a wide range of essential actions in the immune system - also reveal an association between low levels of the vitamin and higher proportion of patients with a COVID-19 positive test.8 This suggests that a low level of vitamin D could be linked to less resistance to SARS-CoV-2 infection. Another study on the mortality rate of COVID-19 and the concentration of vitamin D in national populations highlights a correlation between lower levels of vitamin D and a higher mortality rate from the disease.9
COVID-19 has highlighted the relevance of a holistic approach to preventing and fighting infection. Ensuring that elderly people have regular nutritional counselling and screening to prevent malnutrition and support optimal intake of micronutrients whether at home or in a care environment is key to supporting a more resilient immune system amongst this at-risk population group.
At DSM, we have a deep understanding of the nutritional needs of patients of all ages. That’s why we have an unparalleled record of delivering science-led innovation at every stage of your product’s development. This takes more than ingredients. It takes a partner.
To find out more about how DSM can help you develop medical nutrition solutions to support immune health in elderly patients, sign up to session 2 of the series, titled ‘Optimal Nutritional Care in the Elderly – From Prevention to Rehabilitation’. The live webinar will take place on Wednesday, 7 October 2020 at 14:00-15:00 CET (available on demand after live broadcast). During the webinar, our panel of experts including Dr. Ulrich Suchner, Prof. Philip Calder and Aniza Sheikh will discuss how managing malnutrition in the elderly can play an important role in tackling impaired immune function and post-hospitalization recovery.