Table 3.

Aspects of lifestyle to be addressed to improve immune function.

Diet	• Increase the intake of healthy foods (e.g., vegetables, fruits, nuts, legumes, whole grains, and fish)
	• Decrease the intake of unhealthy foods and drinks (e.g., ultra-processed, refined carbohydrates, added sugars, and fats)
Physical activity	• Increase adherence to (inter)national physical activity guidelines
	• Decrease sedentary behavior
Stress	• Increase active relaxation
	• Decrease chronic stress (e.g., in studies, jobs, and social life)
	• Increase skills and opportunities to cope with chronic stress
Smoking and alcohol	• Decrease the marketing, sale and use of (legal) addictive substances such as tobacco and alcohol
	• Provide help for those addicted
Sleep	• Increase sleeping quality