Association of lactase persistence genotypes (rs4988235) and ethnicity with dairy intake in a healthy U.S. population

Authors: CHIN, ELIZABETH - University Of California, Davis; Huang, Liping; BOUZID, YASMINE - University Of California, Davis; Kirschke, Catherine; DURBIN-JOHNSON, BLYTHE - University Of California, Davis; BALDIVIEZ, LACEY - University Of California, Davis; Bonnel, Ellen; Keim, Nancy; KORF, IAN - University Of California, Davis; Stephensen, Charles; Lemay, Danielle

Submitted to: Nutrients
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2019
Publication Date: 8/10/2019
Citation: Chin, E.L., Huang, L., Bouzid, Y.Y., Kirschke, C.P., Durbin-Johnson, B., Baldiviez, L.M., Bonnel, E.L., Keim, N.L., Korf, I., Stephensen, C.B., Lemay, D.G. 2019. Association of lactase persistence genotypes (rs4988235) and ethnicity with dairy intake in a healthy U.S. population. Nutrients. 11(8):1860. https://doi.org/10.3390/nu11081860.
DOI: https://doi.org/10.3390/nu11081860

Interpretive Summary: The landscape of available dairy products and non-dairy alternatives in the U.S. has been changing in recent decades. In previous studies of other populations, lactase persistence (LP)—the genetic ability to digest lactose into adulthood—has been used as a proxy for milk consumption. It is not known how consumer genetics, such as the ability to digest the major sugar in milk (lactose), and ethnicity influence dairy consumption in the U.S. In the current study, we investigated the association between LP genetics and ethnicity and reported intake of dairy among healthy adults in California. Subjects were asked to report both habitual and recent consumption of milk, cheese, yogurt, and overall total dairy, as well as ‘alternative milk’ products like soy, almond, and rice milk as part of a broader observational trial. Neither LP genetics nor ethnicity influenced whether subjects were consumers or non-consumers of total dairy or specific dairy products, but the amount consumed was associated with these factors. LP subjects consumed more recent intake of total dairy, and more habitual intake of milk than lactase non-persistent subjects. Caucasians consumed more cheese than all non-Caucasian subjects; this finding was consistent for both habitual and recent intake reports. These findings indicate that LP genetics and ethnicity are associated with dairy intake, although the specific findings may differ depending on how consumption is reported (habitual or recent); these factors should all be considered when using LP genetics to predict dairy consumption.

Technical Abstract: Lactase persistence (LP) is a trait in which lactose can be digested throughout adulthood while lactase non-persistence (LNP) can cause lactose intolerance and influence dairy consumption. One single nucleotide polymorphism (SNP ID: rs4988235) is often used as a predictor for dairy intake since it is responsible for LP in people of European descent, with the dominant A allele associated with LP and the G allele with LNP. The objective of this study was to determine whether rs4988235 genotypes and ethnicity influence reported dairy consumption. A multi-ethnic U.S. population was genotyped for rs4988235, and habitual and recent intake of total dairy, cheese, cow’s milk, plant-based alternative milk, and yogurt were estimated from a food frequency questionnaire (FFQ) and 24-hour recall (ASA24), respectively. Within Caucasian subjects, the LP subjects reported consuming more recent total dairy and habitual total cow’s milk intake. For subjects of all ethnicities, GG subjects consumed the least amount of dairy from both dietary assessments, specifically lower compared to AG subjects (ASA24 p = 0.0216). LNP subjects consumed less total cow’s milk than LP subjects when accounting for whether subjects were Caucasian or not (FFQ p = 0.0146). Caucasians consumed more cheese than all non-Caucasian subjects for both assessments (FFQ p = 0.0357, ASA24 p = 0.0152) and more yogurt (ASA24 p = 0.0420). These findings indicate that the rs4988235 genotypes, ethnicity, and dietary assessment methods influence reported dairy intake, and should be considered when determining suitability of rs4988235 as a proxy for dairy intake.