The purpose of this study is to determine whether Yili Lactoferrin ShuHua Milk are effective in reducing the occurrence of flu symptoms.

Inclusion Criteria:

• Age 6 to 12 years, catch cold for 4 to 6 times in last year;
• Age 35 to 45 years, catch cold for 4 to 6 times in recent 3 month;
• Age 60 to 75 years, catch cold for 4 to 6 times in last year;
• BMI 18.5to 29.9kg/m2;
• Able to understand the nature and purpose of the study including potential risks and side effects

Exclusion Criteria:

• Recent (within 6 months of screening) been vaccinated influenza vaccine, or recent (within 15 days of screening) been vaccinated ther vaccines;
• Suffering from rhinitis chronic, laryngitis, labored breathing that similar to flu symptoms. Such as chronic allergic rhinitis, asthma, COPD;
• Long-term use of any prescription or OTC medication that inhibit or prevent flu symptoms, including but not limited to, antihistamine, pectoral, high doses of vitamin C;
• Recent use (within 3 months of screening) of any prescription or OTC medication that significantly affects immune response, such as antibiotic;
• Known allergies to dairy and any substance in the study product;
• History of alcohol, drug, or medication abuse
• Pregnant or breastfeeding women
• Recent daily use (within 3 months of screening) of any probiotics, clabber or yogurt;
• Any comorbidity that could, in the opinion of the investigator, preclude the subject's ability to successfully and safely complete the study or that may confound study outcomes