The investigators believe a readily available drink containing a high dose of probiotics has the potential to improve compliance through many of these mechanisms. This product also has the potential to positively impact the health of children and adults around the world, as yogurt will likely be more appealing to both children and their parents for long term consumption than pharmaceutical-like preparations. In addition to the benefits associated with the consumption of probiotics, there is an increased health benefit from consuming yogurt, a nutrient dense food.

More specifically, the rationale for this Phase I study is to determine safety of this yogurt drink and comply with FDA recommendations pertaining to an Investigational New Drug application. The investigators hypothesize that BB-12 is safe in generally healthy children ages 1-5 years.

Probiotics are live microorganisms that, when administered in sufficient amounts, may improve health. A common use for probiotics is in addressing gastrointestinal issues, such as antibiotic-associated diarrhea (AAD). As an alternative to supplements, probiotics are also included as ingredients in fermented dairy products to produce functional foods, which are foods providing health benefits beyond their nutritional value. Yogurt, for example, is a fermented milk product often considered a functional food. One of the most commonly used probiotics is Bifidobacterium animalis ssp. lactis (BB-12).

Our Primary Aim in Years 1-2 is to conduct a pediatric randomized controlled study to establish the safety of BB-12 fortified yogurt in children. Our Secondary Aims are to examine the fecal microbiota of children prior to, during and following consumption of probiotics. This study will evaluate whether a well-defined, probiotic-containing yogurt can safely be used as an effective delivery vehicle for probiotics. This study is important to help advance probiotic research forward in a systematic, well-accepted manner. Our long-term goal is to create yogurt with sufficient probiotic dosages to positively impact many different aspects of childhood and adult health.

Inclusion criteria for parents/caregivers are:

1. Ability to read, speak and write English or Spanish
2. Access to a refrigerator for proper storage of drink
3. Telephone access

Inclusion criteria for children are:

1. Are between the ages of 1 and 5 years

Exclusion Criteria:

1. Developmental delays
2. Any chronic condition, such as diabetes or asthma, that requires medication
3. Prematurity, birth weight < 2,500 grams
4. Congenital anomalies
5. Failure to thrive
6. Allergy to strawberry
7. Active diarrhea (defined as three or more loose stools for two consecutive days)
8. Any other medicines used except anti-pyretic medicines (to reduce fever) [excluding as needed medications]
9. Parental belief of lactose intolerance
10. History of heart disease, including valvulopathies or cardiac surgery, any implantable device or prosthetic
11. History of gastrointestinal surgery or disease
12. Milk-protein allergy
13. Allergy to any component of the product or the yogurt vehicle
14. During the baseline physical exam, have an oxygen saturation rate <96% and respiratory and pulse rate outside the normal range per their age.

Parents/caregivers will also be asked to refrain from giving their child any probiotic foods or supplements during the entire 2 weeks of the active intervention period, and 2 weeks before day 1 of starting the yogurt. Parents will be supplied with a list of products to avoid.