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Lin Yan

Nutritionist


Lin Yan

Lin Yan, Ph.D.

Research Nutritionist

Biography

Dr. Yan attended graduate school at Texas Tech University, where he earned his doctoral degree in Human Nutrition. Dr. Yan completed his post-doctoral training in the area of selenium and cancer biology at Rutgers University. After that he was a research faculty member at Creighton University School of Medicine and a Nutrition Scientist at DuPont/Solae Company. In 2007 Dr. Yan joined the staff at the Grand Forks Human Nutrition Research Center as a Research Nutritionist. Dr. Yan conducts research in the area of diet, physical exercise, cancer prevention, and metabolic health.

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Research Interests

Dr. Yan's research interests are in the area of diet, physical exercise, and cancer prevention. The prevalence of obesity in Western countries, including the United States, has reached epidemic proportions. Obesity is associated with a low-grade proinflammatory metabolic state that contributes to chronic diseases including cancer. Dr. Yan has investigated the roles of dietary modification (for example, energy balance and selenium supplementation) and physical exercise in prevention of obesity-enhanced primary tumorigenesis and metastasis in rodent models for human cancer.

Dr. Yan’s recent research interest is in the area of modification of diurnal patterns to promote metabolic health. Physiological functions of humans (for example, eating/fasting and wake/sleep patterns) are controlled by the internal biological clock that cycles for approximately every 24 hours. Lifestyle changes in modern world (for example, erratic eating behavior, sleep deprivation, and sedentariness) disrupt the clock and contribute to modern disorders including metabolic dysfunction and obesity. Dr. Yan’s current research focuses on how different types of dietary fat and physical activity alter the biological clock in major organs (for example, liver and fat tissue) and their effects in regulation of metabolism. Outcomes from these investigations will contribute to the knowledge of the extent to which dietary modification and exercise can improve quality life and promote health and well-being.

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Research Accomplishments

Selenium is an essential nutrient to humans. It is a nutrient with cancer prevention potentials. Adequate selenium intake has been associated with lower risk of cancer in both epidemiological studies and clinical intervention trials. Dr. Yan investigated the roles of selenium in secondary cancer prevention – the prevention of malignant spread, which is the most devastating aspect of cancer. Dr. Yan demonstrated that dietary supplementation of selenium reduces pulmonary metastasis in a spontaneous metastasis model of Lewis lung carcinoma. This protection can be also observed in mice with the high-fat diet-enhanced metastasis. Furthermore, Dr. Yan demonstrated that dietary selenium supplementation reduces primary mammary tumor growth and its spread to the lungs in a model for male breast cancer. Male breast cancer is a rare but aggressive disease in men. It remains an unexplored area in cancer prevention. Findings from Dr. Yan’s investigation provide laboratory evidence of usefulness of selenium in secondary cancer prevention.

Adipose tissue produces biologically active inflammatory adipokines that contribute to chronic diseases, including obesity and cancer. Diet-induced obesity enhances primary mammary tumorigenesis in a mouse model for breast cancer and pulmonary metastasis in a model for lung cancer. These enhancements occur with increases in body fat mass and elevations in adipokines in blood [for example, monocyte chemotactic protein-1 (MCP1) and plasminogen activator inhibitor-1 (PAI1)]. Dr. Yan demonstrated that knockout of MCP1 or PAI1 significantly reduces the high-fat diet-enhanced spread of malignant cells to the lung in a mouse model of Lewis lung carcinoma. Furthermore, Dr. Yan demonstrated that adipose specific MCP1 deficiency results in fewer and smaller lung metastases in the Lewis lung carcinoma model and a slower growth rate of primary mammary tumorigenesis in a MMTV-PyMT breast cancer model. These findings are laboratory evidence that adipose-produced adipokines directly contribute to malignant progression. It strengthens our knowledge of obesity in cancer promotion and emphasizes the importance of obesity prevention for health maintenance and cancer prevention.

All mammals exhibit daily patterns in physiological and biological functions including the eating/fasting pattern. Disruption of the daily pattern by eating at a “wrong” time may alter the rhythms of energy metabolism and lead to metabolic disorders including obesity. Dr. Yan investigated the effects of timing of food intake on high-fat diet-induced metabolic disturbance and obesity-enhanced primary tumorigenesis and metastasis in mouse models for human cancer. Time-restricted feeding is a tool used to study timing of food intake in rodents that temporally controlling the eating/fasting pattern to a fixed time of the day. Dr. Yan demonstrated that time-restricted feeding, which does not affect food intake compared to mice with unrestricted feeding, restores the rhythm of energy expenditure, reduces body adiposity, and improves insulin sensitivity. Furthermore, he demonstrated that time-restricted feeding reduces high-fat diet-enhanced mammary tumorigenesis in the MMTV-PyMT breast cancer model and lung metastasis in the Lewis lung carcinoma model. These findings indicate that maintenance of a healthy eating pattern is beneficial in health promotion and cancer prevention.

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