Trends in dietary fiber intake in Japan over the last century.
BACKGROUND
Insufficient intake of dietary fiber (DF) is currently a major problem in the overall promotion of health in the general population in Japan.


OBJECTIVE
To analyze the time trends in DF intake, including DF density (total DF intake/1,000 kcal), and the ratio of water-insoluble fiber to water-soluble fiber (IS ratio) in Japan.


METHODS
The time trend in DF intake in Japan was calculated from data compiled in the Japanese National Nutrition Survey.


RESULTS
The mean daily DF intake (total DF intake) in 1952 was 20.5 g/day, which rapidly declined to about 70 % of the 1952 level in 1970, after which there was little change to 1998. DF density in 1952 was 9.7 g/1000 kcal, which declined by about 30 % in 1970, and remained at about the same level to 1998. The IS ratio has remained stable over this period. Whereas total DF intake and DF density in Japan are similar to those in Western countries, the IS ratios are higher in Japan. Therefore, the higher incidence of, and mortality from, colon diverticulosis, coronary heart disease, hyperlipidemia, etc., which are all thought to be related to fiber deficiency, in Western countries compared to Japan might be due to the differences in the IS ratio.


CONCLUSIONS
A decline in total DF intake and DF density is predicted for Japan in the future, because these parameters were lower among the younger generation. This may be due to the marked changes in the dietary habits of the younger generation, and is a problematic trend for Japanese health.
Nakaji
Shigeyuki
S
Department of Hygiene, Hirosaki University School of Medicine, Zaifu-cho 5, Japan. nakaji@cc.hirosaki-u.ac.jp
Sugawara
Kazuo
K
Saito
Dausuke
D
Yoshioka
Yoshiko
Y
MacAuley
Domhnall
D
Bradley
Terry
T
Kernohan
George
G
Baxter
David
D
D000328:Adult; D000368:Aged; D003327:Coronary Disease / Q000453:epidemiology / Q000401:mortality; D004032:Diet / Q000639:trends*; D004043:Dietary Fiber / Q000008:administration & dosage* / Q000032:analysis; D004241:Diverticulum, Colon / Q000453:epidemiology / Q000401:mortality; D005247:Feeding Behavior; D005260:Female; D005504:Food Analysis; D006293:Health Promotion; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D012995:Solubility