The aging of the global population is accelerating, and the question of how to extend the human life span—especially a healthy life span—has become a hot research topic at home and abroad. As people age, the structure and function of various tissues and organs in the body will successively undergo varying degrees of decline; the rate and manifestation of the aging of each tissue and organ also differ. This decline is the root cause of the poor disease resistance of older people, making them prone to infections and various chronic diseases. Although studies have reported the 12 classic hallmarks of aging, and many cutting-edge research methods have been used to map the cellular atlas of aging, scholars have not been able to elucidate the specific changes in and molecular mechanisms of the aging of specific organs or the interactions between various tissues and organs, limiting the implementation of precise interventions against aging.

Nutritional intervention is an important means of improving and maintaining the body’s health status. The effectiveness of nutritional intervention depends on the precision of the intervention target, which has gradually led to the proposal and maturation of the concept of precision nutrition. The idea of precision in the context of health first emerged in the field of medicine and refers to tailoring treatment to the patient, which requires the provision of an appropriate dose of effective substances to address specific symptoms. In the field of nutrition, in line with the concept of preventive medicine, maintaining the health indicators of the body through nutritional intervention is an effective means to promote health. Therefore, clarifying the changes in key organs and core functions during natural aging and understanding the internal driving factors of these changes are the premises for targeted intervention. Moreover, clarifying the effects and mechanisms of specific nutrients or functional factors for specific populations is the basis for effective nutritional intervention.

The concept of precision nutrition brings new opportunities and challenges to epidemiological research, especially nutritional epidemiology. Based on the high mutation rate of key enzyme gene sites for folic acid utilization in the Chinese population, which leads to high levels of homocysteine in the blood and the risk of stroke, even when blood pressure is effectively controlled during hypertension, Song et al. have proposed and developed a drug suitable for the Chinese population that combines folic acid with antihypertensive drugs. Therefore, we have organized a special issue titled “Precision Nutrition and Health,” focusing on the decline mechanisms of key organs and functions during natural aging, as well as the characteristic mechanisms by which nutrients and functional factors improve health.

The biological functions of nutrients vary in different populations, and the activities of functional factors also have precise mechanisms. In this special issue, Han et al. summarize the key role of specific nutrients in regulating metabolism and immune function, and suggest how individuals may respond differently to specific nutrients, thus paving the way for the formulation of precise and effective nutritional intervention programs. An et al. analyze the cardiometabolic benefits of vitamin D supplementation on blood pressure, lipids, and glucose levels among different populations. Wang et al. demonstrate that grape seed extract procyanidin C1 (PCC1) relieves inflammatory bowel disease by prompting the gut microbiota to secrete valeric acid, which subsequently regulates autophagy in intestinal epithelial cells and enhances mucus secretion. Lin et al. target intestinal stem cells, which play a fundamental role in intestinal repair for older people, people with intestinal problems, and patients after surgery, and microRNA in intestinal stem cells (e.g., miR-29a and miR-29b), which target Hnf4g expression to inhibit fatty-acid-oxidation-mediated oxidative phosphorylation and then promote regeneration of the tissue.

Immune function, the lungs, and the intestines have their own aging patterns; their aging characteristics and the underlying driving factors also differ. In this issue, Wu et al. report that aging bone marrow produces more polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) that circulate to other organs, including the intestine, which is the major reason for the susceptibility to Clostridium difficile infection in older people. Quan et al. investigate the role of aging-related epithelial dysfunction in pulmonary fibrosis and reveal that aging alveolar type 2 progenitor (AT2) cells can promote collagen type I (Col I) synthesis and accelerate the progression of pulmonary fibrosis by directly communicating with fibroblasts through the secretion of plasminogen activator inhibitor-1 (PAI-1) factor. Song et al. explore the mechanisms of protein digestion and absorption in older people, clarify the impact of aging on intestinal absorption, and reveal the key role of the L-type amino acid transporter 2 (LAT2) in the decline of protein utilization. Yu et al. evaluate the impact of fecal microbiota transplantation from young mice on skin rejuvenation in aged mice, which primarily works by increasing the abundance of Lactobacillus and Lactococcus and elevating tryptophan and its metabolites.

In the future, research on the driving factors of aging, disease occurrence and development, and the roles of specific nutrients in these processes will be of great significance in promoting the development of precision nutrition and health engineering and the realization of nutrition interventions to improve health.