Cancer Causes and Control, 1, 149 - 154

Diet and age at menarche

Jocelyne Moisan, Francois Meyer, and Suzanne Gingras (Received 6June 1990; accepted 25 June 1990) Early menarche has been associated with higher risk of breast cancer. A prospective study has been conducted in Quebec City, Canada, to evaluate the relationship of dietary intake to age at menarche. On three occasions during the schoolyear 1986 - 87, 2,299 pre-menarcheal girls kept a three-day dietary record. At the end of a 17-month follow-up, 911 girls (39.6 percent) had reached menarche. Incidence density ratios (IDRs) adjusted for age at entry and mothers' age at menarche were computed using proportional hazards models. IDRs for quartiles of energy, nutrient and food-group intakes were not different from the null value. In this population of well-nourished girls, diet did not influence the age at onset of menarche.

Key words: Adolescence, diet, follow-up study, menarche.

Introduction Some investigators have attempted to evaluate the relationship between diet and breast cancer. Experimental I and correlational 2 studies suggest that high fat diets, and particularly diets rich in animal fats, increase the breast cancer risk. Results from case-control ~-7 and cohort studies ~'9 do not confirm these hypotheses. As compared to dietary patterns in adulthood, those during childhood and adolescence are considered more important in relation to the risk of developing breast cancer. 8 Women who experience menarche at an early age are at higher risk of developing breast cancer. 8'1° - 13 It is possible that the same dietary factors influence both age at onset of menses and risk of breast cancer. The purpose of this study was to evaluate the relationship of diet to menarche, taking into account other known determinants of onset of menstruation.

Subjects and methods The study population and the baseline data-collection procedure have been described elsewhere. 14 In brief, during the schoolyear 1986-87, information was collected about the dietary intake of 3,022 girls attend-

ing fifth grade classes in the Quebec City area. One hundred and seven girls already had reached menarche by the time of first contact in the Fall of 1986, but most (2,915) were pre-menarcheal. On three occasions (the first, between September and December 1986; the second, between January and March 1987; and the third, between April and June 1987), all girls were asked to keep a three-day dietary record. In the Fall of 1986, a questionnaire about the girl and her family was filled out by each subject's parents. Body weight, height, and two skinfold thicknesses were also measured for 98 percent of the subjects during the schoolyear. Of the 2,915 pre-menarcheal girls originally enrolled, 2,415 (82.8 percent) provided three dietary records apiece. During the Fall of 1987 and 1988, a letter was sent to the mothers of all pre-menarcheal girls to ask if the subjects' menarche had occurred since the last contact, and if it had occurred, to determine the month and year of the first period. Information was obtained for 2,390 (99.0 percent) girls (nine were lost to follow-up and 16 refused to answer). Of these, 91 had reached menarche before June 1987. The study population was restricted to the 2,299 girls who provided three dietary records and who had not menstruated by the time of the third dietary-record collection in the Spring of 1987. Duration

The authors are in the D~partement de m~decine sociale et pr~ventive, Facult~ de Mgdecine, Universit~ Laval. Correspondence and repm'nt requests should be addressed to Francois Meyer, D~partement de m~decine sociale et prgventive, Facultg de Mgdecine, Universit~ Lava], Ste-Foy, Quebec, Canada G1K 7P4. This work was supported by a research grant from the National Cancer Institute o f Canada. The study was conducted in part while J. Moisan was the recipient o f a Ph.D. Fellowship from the Fonds de la Recherche en Sant~ du Quebec. F. Meyer is a research fellow o f the Fonds de la Recherche en Sant~ du Quebec.

©1990 Rapid Communicationsof Oxford Ltd

149

J. Moisan, F. Meyer, and S. Gingras of follow-up ranged from five to 606 days, with a median and average of 17 months. At the time of the 1987 Fall contact, 196 girls had reached menarche. At the end of the follow-up period in the Fall of 1988, 911 girls (39.6 percent) had reached menarche and 1,388 (60.4 percent) were still pre-menarcheal. Nutrient intakes were computed from the dietary records using a food composition table based mostly on the Canadian nutrient file. 15 Nutritive values of commonly used composite dishes and information obtained from the food industry were added to the file. This database gave nutrient values for a total of 750 food items. The nutrient database was applied to each of the three dietary records to obtain the mean daily intakes of energy and selected nutrients: proteins; carbohydrates; lipids; saturated, mono-unsaturated, and poly-unsaturated fatty acids; cholesterol; calcium; iron; phosphorus; crude fibers and vitamins A, B6, B12, C, D and E, folacin, niacin, riboflavin, and thiamin. All food items were assigned, according to their composition, to one or more of the following nine food groups: (i) milk and milk products; (ii) meat, poultry, fish, and eggs; (iii) legumes and nuts; (iv) breads and cereals; (v) vegetables; (vi) fruits and fruit juices; (vii) oils and fats; (viii) pastries and sugars; (ix) soft drinks. Standard portions were determined using the Canadian Food Guide recommendations for the first six groups. 16 The oils and fats group standard-portion was defined as one tablespoon for all foods included in the group. The standard portion for sugar, molasses, and syrups was defined as one tablespoon also. For cakes, pastries, and pies, this consisted of one unit (an individual cake), or one usual portion (one piece of cake). The soft drinks standard portion was 250 ml. Mean daily numbers of portions of each food group were defined by adding and averaging the total numbers of portions of each food group noted in the three dietary records. Covariance anlayses were used to estimate the means of nutrient and food portion intakes among girls who experienced menarche before the end of the two-year follow-up and among non-menarcheal girls. Differences between means were tested using the F statistic. To assess the association between exposure variables and the onset of menstruation, and to adjust for confounding factors (the girls' ages at the beginning of the study and the mothers' ages at menarche), incidence density ratios (IDRs) and their 95 percent confidence limits (CL) were computed using proportional hazards models. 17 Independent variables were previously converted from continuous to ordered categorical variables based on the quartiles of their distribution among the entire study population. In each case, the lowest quartile was the reference category. Analyses were computed with the Statistical Analysis System package. TM 150

Results At the beginning of the follow-up, after the third dietaryrecord collection, the girls' ages ranged from 9.5 to 13.3 years with a median of 11.1 years. The age distribution was as follows; under 10, 0.6 percent; 10.0 to 10.9, 37.8 percent; 11.0 to 11.9, 57.9 percent; 12 and over, 3.7 percent. Girls who had reached menarche before the end of the follow-up had a statistically-significant higher mean age at the beginning of the study (11.2 years) than girls who were still pre-menarcheal in the Fall of 1988 (11.0 years). The age at menarche of menstruating girls ranged from 10.1 to 14.7 years with a median of 12.1 years. Menstruating girls had mothers who had reached menarche before non-menstruating girls' mothers (IDR = 0.83 [0.79-0.87] per year of increment in the mothers' ages at menarche). To take into account the effects of age at entrY and of the mothers' ages at menarche on the onset of menses, means and IDRs were adjusted for these two variables. No statistically significant differences in mean intakes of energy and macronutrients were observed (Table 1). Proportions of energy provided respectively by proteins

Table 1. Means of daily nutrient intakes with standard error of means (SEM) among 911 girls who experienced menarche before the end of follow-up and 1,388 non-menarcheal girls, adjusted for age and mothers' ages at menarche Menarche

Yes Energy intake (kJ) Proteins (g) Carbohydates (g) Lipids (g) --saturated (g) --mono-unsaturated (g) --poly-unsaturated (g) Cholesterol (mg) Calcium (mg) Iron (mg) Phosphorus (mg) Vitamin A (RE) Vitamin B6 (rag) Vitamin B12 (/*g) Vitamin C (mg) Vitamin D (IU) Vitamin E (mg) Folacin (#g) Niacin (NE) Panthotenic acid (mg) Riboflavin (rag) Thiamin (mg) Crude fibers (g)

7361 (48.66) 70.6 (0.49) 213.6 (1.59) 66.5 (0.51) 26.7 (0.23) 25.4 (0.20) 8.5 (0.09) 250.3 (2.58) 1027 (12.69) 11.1 (0.08) 1249 (11.45) 898 (16.06) 1.2 (0.01) 4.1 (0.07) 105.3 (1.74) 252.7 (4.00) 6.2 (0.09) 156.1 (1.71) 25.4 (0.18) 4.5 (0.04) 1.9 (0.02) 1.4 (0.01) 3.3 (0.05)

ap-value for means comparison < 0.05.

No 7249 (39.10) 70.0 (0.40) 209.7 (1.28) 65.6 (0.41) 26.6 (0.19) 24.9 (0.16) 8.3 (0.07) 248.3 (2.08) 1029 (10.19) 10.9 (0.07) 1244 (9.20) 925 (12.91) 1.2 (O.Ol) 4.1 (0.06) 100.1a (1.39) 253.8 (3.22) 6.1 (0.07) 156.8 (1.38) 25.2 (0.14) 4.5 (0.03) 1.9 (0.02) 1.4 (O.Ol) 3.3 (0.04)

Diet and age at menarche

(menarcheal, 16.3 percent; non-menarcheal, 16.5 percent), carbohydrates (menarcheal, 49.4 percent; nonmenarcheal, 49.1 percent), and lipids (menarcheal, 34.3 percent; non-menarcheal, 34.4 percent) were similar for the two groups. Regarding vitamin intake, only that of vitamin C was statistically higher among menstruating girls than among non-menstruating ones. Intakes of calcium, iron, and phosphorus were not statistically different between the two groups. Crude fiber intake was almost identical in the two groups. Dietary intakes reported by the girls were in agreement with what was expected for females in this age range. The study population was fairly homogeneous and only moderate variations of intakes were observed. The median of the first and fourth quartiles were 5,712 and 8,876 kJ for energy intake, and 49.3 and 83.2 g for total lipids respectively. IDRs for quartiles of nutrient intakes ranged from 0.8 to 1.3 (Table 2). Only the IDR for the fourth quartile of mono-unsaturated fat intake was statistically different from the null value. Mean daily intakes in the breads and cereals, fruits, and soft-drinks groups were statistically significantly higher among menarcheal girls (Table 3). IDRs by quartiles of food group intakes were not statistically different (Table 4). Statistically significant positive associations were found between body weight, height, body mass index (weight/

height2), abdominal and supra-iliac skinfolds, and menarche (Table 5). Adjustment for body weight did not alter previous observations on nutrient and food group intakes.

Discussion In our data, diet was not associated with age at onset of menstruation. The observed differences between means of intake of vitamin C, breads and cereals, fruits, and soft drinks, were statistically significant; but these differences were very small. The IDR of the fourth quartile of mono-unsaturated fat intake was a little high. These observations have no practical importance. Undemutrition and anorexia nervosa have been identified as factors which delay the onset of menses. 19,20It is not so clear how variations within an adequate dietary pattern can influence menarche. In previous studies, associations between diet and menarche were found, but results are not consistent, Some authors have reported associations between early menarche and high energy intake, 14,21,22high fat intake, 23 high protein intake, 24 or low fiber intake. 25 High meat consumption has been associated with early menarche, 26'27 whereas vegetarian diets have been associated with later menarche. 24'26 The discrepancies between studies, including the one reported here, can be attributed to differences in study designs

Table 2. IDRs with 95 percent confidence limits (CL) of menarche according to quartiles of nutrient intakes among 911 girls who experienced menarche before the end of follow-up and 1,388 non-menarcheal girls, adjusted for age and mothers' ages at menarche Quartiles Q1

Q2

Q3

Q4

Energy intake Proteins Carbohydrates Lipids --saturated --mono-unsaturated --poly-unsaturated Cholesterol Calcium Iron Phosphorus Vitamin A

1 1 1 1 1 1 1 1 1 1 1 1

0.9 (0.8- 1.2) 1.0 (0.8- 1.2) 0.8 (0.7- 1.0) 1.0 (0.9- 1.2) 1.2 (1.0- 1.4) 1.1 (0.9- 1.3) 1.1 (0.9- 1.3) 1.1 (0.9- 1.3) 1.1 (0.9- 1.3) 1.1 (0.9-1.4) 1.0 (0.9- 1.3) 1.0 (0.8 - 1.1)

1.1 (0.9- 1.3) 1.1 (0.9- 1.3) 1.0 (0.9- 1.2) 1.0 (0.8- 1.2) 1.1 (0.9- 1.3) 1.0 (0.8- 1.2) 1.1 (0.9- 1.3) 1.1 (0.9- 1.3) 0.9 (0.8- 1.1) 1.1 (1.0-1.4) 1.0 (0.8- 1.2) 1.1 (0.9- 1.3)

1.1 (0.9- 1.4) 1.1 (0.9- 1.4) 1.1 (0.9- 1.3) 1.1 (0.9- 1.4) 1.1 (0.9- 1.3) 1.3 (1.1 - 1.5) 1.1 (0.9- 1.4) 1.1 (0.9- 1.3) 1.0 (0.8- 1.2) 1.2 (1.0-1.4) 1.1 (0.9- 1.3) 0.8 (0.7- 1.0)

Vitamin B6 Vitamin B12 Vitamin C Vitamin D Vitamin E Folacin Niacin Pantothenic acid Riboflavin Thiamin Crude fibers

1 1 1 1 1 1 1 1 1 1 1

1.0 1.1 1.0 1.2 1.0 0.9 1.1 0.9 1.0 0.9 0.9

0.9 1.0 1.1 1.0 1.1 1.1 1.1 1.0 1.0 1.2 0.9

1.1 1.0 1.1 1.0 1.1 1.1 1.2 1.0 1.0 1.0 0.9

(0.8 (0.9(0.9(1.0(0.8(0.8(0.9(0.8(0.8 (0.7(0.8 -

1.2) 1.3) 1.2) 1.4) 1.2) 1.1) 1.4) 1.1) 1.2) 1.0) 1.1)

(0.7 (0.8(0.9(0.8(0.9(0.9(0.9(0.8(0.8 (1.0(0.8-

1.1) 1.2) 1.4) 1.3) 1.3) 1.3) 1.3) 1.1) 1.2) 1.4) 1.1)

(0.9(0.8(0.9(0.8(0.9(0.9(1.0(0.8(0.8 (0.8(0.7-

1.3) 1.2) 1.4) 1.2) 1.3) 1.3) 1.4) 1.2) 1.2) 1.2) 1.1)

151

J. Moisan, F. Meyer, and S. Gingras or in subject selection, or to the validity of diet assessment methods used. The lack of association between diet and menarche could have resulted from exclusion of girls with the earliest menarche from the study population (107 before

Table 3. Means and standard error of means (SEM) of number of portions of food groups consumed daily among 911 girls who experienced menarche before the end of follow-up and 1,388 non-menarcheal girls, adjusted for age and mothers' ages at menatche Menarche Yes No Mean (SEM) Mean (SEM) Milk and milk products Meat, poultry, fish, eggs Legumes and nuts Breads and cereals Vegetables Fruits and fruit juices Oils and fats Pastries, sugars Soft drinks

3.91 4.54 0.39 7.82 4.12 4.14 0.95 3.29 0.73

(0.05) (0.04) (0.01) (0.07) (0.04) (0.07) (0.02) (0.06) (0.02)

3.93 4.52 0.40 7.61a 4.12 3.95a 0.91 3.32 0.66a

(0.04) (0.03) (0.01) (0.06) (0.04) (0.05) (0.02) (0.05) (0.02)

"P-value for comparison of means < 0.05.

the first contact and 91 between the first and third). These girls were older and heavier than those enrolled in the follow-up study, but dietary intakes were remarkably similar in the two groups. Mean intakes of energy and total lipids were respectively 7,240 kJ and 65.9 g for those excluded, and 7,293 kJ and 66.0 g for those enrolled in the follow-up study. In our prospective study, exposure data were collected before the onset of menses for all subjects. Three other studies have used prospective data. In a preceding paper, we reported a case-control analysis on 666 girls selected in the present cohort. ~4 The cases were 333 girls who reached menarche during the first year of follow-up. Controls were age-matched non-menarcheal girls. Age-adjusted mean of energy intake was slightly higher in cases (7,796 kJ/day) than in controls (7,419 kJ/day). The observed association was weak and not practically important. Kissinger et al. 26 administered 24-hour dietary recalls to 1,000 pre-menarcheal girls, aged 9 to 15 years. They found an association between high meat consumption and early menarche a m o n g the 230 girls who had reached menarche before the end o f the study. They did not give information on the remaining girls. During 1979 in the Quebec City area, 109 pre-menarcheal girls, aged 9 - 12 years, provided

Table 4. IDRs and 95 percent confidence limits (CL) of menarche according to quartiles of food portion intakes among 911 girls who experienced menarche before the end of follow-up and 1,388 non-menarcheal girls, adjusted for age and mothers' ages at menarche Quartiles Milk Meat Legumes Breads Vegetables Fruits Oils and fats Sugars Soft drinks

QI

Q2

1 1 1 1 1 1 1 1 1

1.1 (0.9 1.1 (0.9 1.0 (0.9 1.1 (0.91.0 (0.91.1 (0.9 0.9 (0.8 0.9 (0.8 1.0 (0.8-

Q3 1.4) 1.3) 1.2) 1.4) 1.2) 1.3) 1.1) 1.1) 1.3)

Q4

1.0 (0.8 1.0 (0.8 1.0 (0.8 1.2 (1.01.1 (0.91.0 (0.81.0 (0.90.9 (0.8 1.2 (1.0-

1.2) 1.2) 1.2) 1.5) 1.4) 1.2) 1.2) 1.1) 1.4)

1.1 (0.9 1.0 (0.8 1.0 (0.8 1.2 (1.00.9 (0.81.1 (0.9 1.2 (1.01.0 (0.8 1.3 (1.0-

1.3) 1.2) 1.2) 1.5) 1.1) 1.3) 1.4) 1.1) 1.5)

Table 5. IDRs with 95 percent confidence limits (CL) of menarche according to quartiles of anthropometric variables among 911 girls who experienced menarche before the end of follow-up and 1,388 non-menarcheal girls, adjusted for age and mothers' age at menarche Quartiles Q1 Body weight Height Body mass index Supra-lilac skinfold Abdominal skinfold aBMI = weight (kg) / height (m)2. 152

1 1 1 1 1

Q2 1.9 (1.51.3 (1.11.8 (1.41.6 (1.3 1.5 (1.2-

2.4) 1.7) 2.7) 2.0) 1.9)

Q3

Q4

3.4 (2.7- 4.2) 2.5 (2.0- 3.1) 2.7 (2.2- 3.4) 2.2 (1.8 - 2.7) 2.2 (1.8-2.7)

5,8 (4.7- 7.2) 4.5 (3.7- 5.6) 3.4 (2.8- 4.2) 2.8 (2.3 - 3.4) 2.5 (2.1- 3.1)

Diet and age at menarc/3e morphologic and dietary data. 21 Their age at menarche was ascertained in 1986. Dietary energy intake showed a positive association with early age at menarche (RR = 2.8, controlling for age and weight). No significant associations were observed between specific nutrients and age at menarche. 21 Age at menarche and food intake data were collected concurrently in other studies where association between diet and age at menarche was found. 22-24'27 In a correlational study, Hughes et al. 25 found a positive correlation between dietary fiber and age at menarche. Cross-sectional and correlational studies are less fitted than prospective studies to investigate cause-effect relationships. The limitations of dietary records and food composition tables in the assessment of habitual dietary intake are well-documented) ~'28-~° Dietary records tend to underestimate current food consumption. Nondifferential misclassification would attenuate observed associations. In this study, the food data collection was similar for all girls and took place before the onset of menses for all subjects. As misclassification error should be random, any effect would be to reduce true effect measures. Dietary assessment methods used in other studies were, for the most part, less valid than dietary records. Authors used 24-hour dietary recalls 23'26 and short questionnaires, 22 compared vegetarians to nonvegetarians, 24 classified girls according to their response to one question into 'proteinous,' 'mixed,' or 'catbohydratic' groups, 27 and compared data from the Food and Agriculture Organization reports. 25 In our study, almost all the girls were Caucasian and lived in the same area. Other studies compared girls from different ethnic origins, 22'23 different countries, 25 or with different lifestyles. 24 The associations found in these studies, between nutrient intakes and age at menarche, could be explained by differences in other determinants of menarche. Previous studies have raised hypotheses about the relation between diet and age at menarche. High intakes of energy, proteins, or fats have been associated with earlier menarche in other populations. Our data showed that none of these nutrients had a significant effect on the onset of menstruation. A high fiber intake was associated with a later age at menarche in a correlational study. There was no association in our data. Vegetarian diets have been associated with a lower likelihood of menstruating at an early age than non-vegetarian diets. No girls in our study population were vegetarians. The intake of meat, poultry, fish, and eggs was not different among girls who reached menarche and among non-menarcheal girls. In summary, our data showed that none of the nutrients and none of the food groups studied had

a significant effect on onset of menstruation. The prospective design and the high power of this study have allowed associations to be observed between anthropometric characteristics and the onset of menstruation.

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Diet and age at menarche.

Early menarche has been associated with higher risk of breast cancer. A prospective study has been conducted in Quebec City, Canada, to evaluate the r...
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