Factor

Impact on the lungs

Diet (1)

• Research has shown that poor nutritional status predisposes an individual to infection.
• High intake of fresh fruit and vegetables appears to have a beneficial effect on lung health and their consumption are recommended on a daily basis.

Dietary fibre and prebiotics (1,2,3,4)

• Dietary fibre is a good source of microbiota accessible carbohydrates which provide the host with energy and improves intestinal health.
• The beneficial effects of prebiotics are thought to be mediated primarily by increased absorption of short chain fatty acids (SCFAs) from the colon microbiome, providing protection against airway inflammation in the lungs through the induction of T regulatory cells and strengthening of the gastro-intestinal associated lymphoid tissue (GALT).
• A fibre rich diet changes not only the intestinal microbiota, but can also affect the lung microbiota, indicating influence of nutrition on lung immunity.
• Dietary sources of prebiotics

Vitamin D  (1,5,6,7,8,9)

• Several meta-analyses have concluded that vitamin D supplementation reduces the risk of respiratory tract infections (RTIs) in both children and adults.
• Deficiency can increase lung permeability and reduce pulmonary barrier integrity.
• Activation of vitamin D in the lung induces antimicrobial peptides and reduces inflammatory cytokines in response to viruses.
• Serious deficiency is common among elderly housebound people in aged care facilities, nursing homes and long stay wards. This has been identified as an important public health problem.
• Sources of vitamin D

Vitamin C

(1,10)

• An effective antioxidant that enhances activity and function of immune cells.
• Deficiency leads to:
  • Impaired immunity and increased susceptibility to infection.
  • Increased risk of contracting pneumonia and increased disease severity.
• Supplementation is effective in both prevention and treatment of RTIs, reducing both incidence and duration.
• Long-term vitamin C intake is significantly associated with improved lung function.
• Elderly people are at higher risk of vitamin C deficiency and are more likely to have a compromised immune system.

Zinc

(1,11)

• Plays a role in mediating the inflammatory response and may reduce the incidence of infection in healthy elderly individuals.
• Zinc supplementation (45mg/day) in healthy elderly individuals improves immune function and reduces the incidence of infections.
• Zinc supplementation in children under 5 reduces the risk of pneumonia by 13%.
• Emerging research clarifies zinc’s involvement in the onset of pulmonary diseases.
  • Abnormality in the zinc transport mechanism influences obstructive pulmonary diseases.
  • Zinc supplementation alone is not sufficient for treatment in obstructive pulmonary diseases. A therapeutic approach that takes the transport mechanisms into consideration is necessary.

Vitamin A

(12,13)

• Contributes to key biological processes including epithelial differentiation and immune responses.
• Involved in the proliferation and maintenance of epithelial cells, including those of the respiratory tract.
• During infectious diseases, particularly RTIs, plasma retinol levels decline inducing an increased susceptibility to infection creating a “vicious circle”.

Omega-3 fatty acids (10)

• Dietary intake of polyunsaturated fatty acids (PUFAs), primarily from a seafood rich diet, appears to play a role in lung diseases.
• Increased intake of omega-3 fatty acids can reduce the inflammatory response by changing the contents of lipid membranes and other substrates which are in turn the substrates for eicosanoid production.

N-Acetyl cysteine (NAC)

(14)

• In vitro and in vivo studies show that NAC protects the lungs against toxic agents by increasing pulmonary defence mechanisms through its direct antioxidant properties and its indirect role as a precursor of glutathione synthesis.
• Treatment with NAC in humans alters the pulmonary oxidant–antioxidant imbalance.
• Oral administration of 600 mg/day improves lung function.

Probiotics

(1,15,16)

• Improve or alleviate lung disease conditions by regulating the immune system via immunomodulation of local immunity (by maintaining gut wall integrity) and systemic immunity (by enhancing non‐specific and specific arms of the immune system).
• More effective than placebo in reducing episodes of acute upper RTIs by ~47%. Further quality trials are needed to confirm this finding.
• LGG and Lactobacillus casei strains Shirota (LcS) and DN114001 may be beneficial in the prevention and/or treatment of bacterial and viral infections in the gastrointestinal and respiratory systems, including influenza.
• Nutritional factors affecting the gut-lung axis

Exercise

(17,18)

• Physical fitness and moderate intensity exercise training have been shown to improve immune responses to vaccination and chronic low-grade inflammation.
• Exercise improves various immune markers in several disease states.
• Regular bouts of short-lasting (i.e. up to 45 minutes) moderate intensity exercise are “immunoenhancing” whereas repeated bouts of long-lasting (>2 hours) high intensity exercise can be “immunosuppressive”.

Sleep quality

(19,20)

• Poor sleep increases susceptibility to certain infections such as the common cold and is associated with increased inflammatory markers.
• A systematic review of previous meta-analysis has shown exercise improves selected sleep outcomes in adults.