Table 1.

Descriptive characteristics of included studies.

Author Details	Country of Study	Study (Cohort) Name	Sample Size	Age (Years)	% Female	Duration of Follow-Up (Years)	Breakfast Evaluation Method	Exposure (Breakfast) Definition	Outcome(s)
Cahill et al., 2013 [21]	US	Health Professionals Follow-Up Study	26,902	45–82	0.0	16.0	Questionnaire (self-administered)	Breakfast was defined as a positive response to any of the first three eating times (‘before breakfast’, ‘breakfast’, ‘between breakfast and lunch’)	Incident coronary heart disease (CHD); defined as non-fatal myocardial infarction (MI) or fatal CHD
Kubota et al., 2016 [22]	Japan	The Japan Public Health Center-Based Prospective (JPHC) study	82,772	45–74	53.3	12.7	Questionnaire (self-administered)	Participants were classified into the following four groups; those who had breakfast 0 to 2 (subjects with almost never, those with 1–3 times/month, and those with 1–2 times/week were combined because of the small number of those with 1–3 times/month or 1–2 times/week), 3–4, 5–6, or 7 (everyday) times/week. Those who had breakfast 7 times/week were regarded as the reference group.	Stroke and CHD (i.e., myocardial infarction and sudden cardiac death)
Rong et al., 2019 [23]	US	National Health and Nutrition Examination Survey III	6550	40–75	52.0	18.8	Home-based interviews	Participants were asked “How often do you eat breakfast?” during the household interview, and the possible answers included “every day,” “some days,” “rarely,” “never,” and “weekends only.” The frequency of breakfast eating was classified as “never,” “rarely,” “some days,” or “every day.”	Death from cardiovascular disease (CVD) (defined as heart disease or stroke; ICD codes: (I00–09, I11, I13, I20–51, I60–69), heart disease, stroke, or all-cause death.
Yokoyama et al., 2016 [24]	Japan	The Japan Collaborative Cohort Study (JACC) Study	83,410	40–79	59.1	19.4	Questionnaire (self-administered)	The type of breakfast consumed was assessed according to the following five categories: Japanese style, Western style, Chagayu style (tea rice gruel), no or nearly no breakfast eaten, or other. Participants were classified into two groups, as those who eat breakfast (including Japanese style, Western style, Chagayu style (tea rice gruel), and other) and those who skip breakfast (no or nearly no breakfast eaten).	Deaths from circulatory diseases (I00–I99) or all-cause death.