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Improved retinol, carotene, ferritin, and folate status in Nuxalk teenagers and adults after a health promotion programme

Abstract
Introduction
Methods
Results
Discussion
Acknowledgements
References

Harriet V. Kuhnlein and Sandy Burgess

Harriet Kuhnlein is affiliated with the Centre for Indigenous Peoples’ Nutrition and Environment (CINE) and the School of Dietetics and Human Nutrition at McGill University in Ste. Anne de Bellevue, Quebec, Canada. Sandy Burgess is with the Medical Services Branch, Health Canada, Western Region, in Bella Coola, British Columbia, Canada.

Abstract

Plasma retinol and carotene, erythrocyte folate, serum ferritin, and haemoglobin were determined in native people living on the west coast of British Columbia before and after a three-year intervention programme of nutrition education and health promotion emphasizing local cultural food. One hundred ninety-nine persons participated before (T₁) and 267 after (T₂) the programme, with 107 persons participating in both periods. Overall T₂ mean ± SEM adult (20-60 years) retinol increased (p <.05) over T₁ from 23.8 ± 0.5 to 42.4 ± 17.3 µg/dl, carotene increased from 37.4 ± 1.2 to 54.1 ± 1.6 µg/dl, and erythrocyte folate increased from 226 ± 8 to 264 ± 8 ng/ml. T₂ mean ± SEM adult ferritin and haemoglobin for all ages/sexes combined did not change; however, haemoglobin for older women 41 to 60 years of age increased (p <.05) from 12.4 ± 0.4 to 13.2 ± 0.2 g/dl, and the percentage of teenagers at risk for low ferritin levels was reduced for females from 85% to 17% and for males from 50% to 11%. It was concluded that the intervention programme improved vitamin A and folate status for the overall community and iron status for teenagers.

Introduction

Vitamin A, iron, and folate are nutrients generally recognized to be limited in diets of the poor in many developing countries. They have been noted as problem nutrients in diets of Canadian indigenous peoples residing in rural and northern communities. Although there are many dietary sources of these nutrients, all three may be consumed below recommended levels when people can no longer acquire the full array of their preferred, culturally defined local food sources.

Rural and northern Canadian indigenous peoples have limited consumption of imported market food items that are recognized sources of these nutrients (such as fresh vegetables, fruits, dairy products, and meats) because of barriers in cost and acceptability. With the exception of fish and game as sources of iron and retinol, there may also be limited consumption of local sources of these nutrients [1-7]. Because vitamin A, iron, and folate contribute to many interconnected physiological functions in people of all ages and both sexes [7, 8], it is relevant to investigate their biochemical indicators simultaneously in a population at risk. Therefore, after a pilot study that identified adult women as having low dietary levels of these three nutrients [9], an intervention programme emphasizing local cultural food sources was conducted with the Nuxalk Nation in British Columbia. Nutritional status evaluations were conducted before (T₁) and after (T₂) the programme.

The Nuxalk Nation is located in the valley of the Bella Coola river in an isolated section of the west coast of British Columbia, Canada. Approximately 800 First Nations people live in 150 homes on the reserve. At the time of this research, unemployment was over 30%, and the formal education of the residents rarely exceeded the ninth grade. Fishing and logging industries provide seasonal employment for men; other employment is in local commerce and services [10].

The food system traditional to the Nuxalk culture emphasizes fish, particularly salmon, other seafoods, game, berries, roots, greens, the inner bark of trees, and fats of marine origin. These have been described in other publications [9, 11-17]. During the last 150 years, several factors have contributed to a decline in use of the traditional food system: the increasing availability of market foods; the interruption of knowledge transfer to younger generations on how to harvest, preserve, and prepare traditional food items; demographic changes increasing the pressure on food harvested within the allocated reserve; and legislation restricting traditional food resource use [18, 19]. Generally recognized health problems of the Nuxalk parallel those for other isolated and semi-isolated native communities in Canada: obesity, dental caries, alcoholism, diabetes, high-risk infants, and problems of mental health [20-22].

A nutrition education programme promoting the use of locally available traditional food resources and general health promotion was conducted within the Nuxalk Nation from June 1983 until May 1986 [11, 23]. The programme was developed with full support and advice from the Nuxalk Nation Council and elders and with the full participation of community members. An advisory committee guided programme activities and was composed of the community health nurse, the community health representative, the alcohol and drugs counsellor, and a representative of the Council who held the health portfolio. The overall strategy was to use traditional knowledge and the traditional food system to stimulate dietary and lifestyle improvements. Various educational strategies and activities were conducted [23], which included food events demonstrating traditional and contemporary techniques of harvest preservation and preparation, and feasts. For example, popular events were community construction offish-smoking houses, training sessions for teenagers and young adults in safe fish-processing using pressure canners, and community berry and other plant-harvesting excursions. Activities in schools conducted by programme staff (two community residents who were trained as nutrition aides) included sessions on dental health and food use, fitness events, and other educational activities on nutrition. During the three-year period, a total of 375 educational events took place [23], and all households and community residents were invited to participate. Attendance records were kept whenever possible, and the final tally of event participants was 7,521, although it was obvious that in this community of approximately 800 people, many participated in multiple activities. Food use interviews conducted in late 1985, the third year of the programme, revealed that families reported that programme activities caused substantial increases in the use of fish, fish oil, berries, and greens in comparison with a similar earlier survey [23]. The survey also demonstrated that although costs of market food increased, families spent less on food at the local store, and that this was directly related to increased use of home-harvested and preserved food and economical shopping practices learned in programme activities [23].

The effectiveness of the programme was also evaluated in two periods of “health assessments” conducted in the community in 1983 before (T₁) and in 1986 immediately after (T₂) the intervention activities. In both periods, the assessments were done in mid-May, with approximately 70% attendance of registered band members who were in residence in the community at the time. The entire Nuxalk food and nutrition programme, including the health assessments, was approved by the Nuxalk Nation Council and the University Committee on Human Ethics. Consent was obtained from all persons participating in the health assessments. In reviewing the list of those attending and not attending the assessments, it was the judgement of local health personnel that those who did not attend the health assessment activities were, as a group, no different in food use or diagnosed health conditions from those who attended. Similarly, health personnel found no obvious differences in the characteristics of those attending assessments at T₁ and T₂. The assessments included anthropometric, fitness, dietary, dental, vision, hearing, and blood pressure measurements, as well as evaluation of key nutrient parameters in blood samples [24]. Blood samples were taken from persons 13 years and older who volunteered the sample. This report gives the results on the differences in plasma retinol and carotene, serum ferritin, haemoglobin, and erythrocyte folate in blood samples of teenagers and adults before (T₁) and immediately after (T₂) the nutrition education and health promotion intervention programme.

Methods

Sample collection

In each period, approximately 30 ml of non-fasting venous blood was taken from each person by a technician. These samples were treated, portioned, and frozen for shipment to the laboratory, where they were stored at - 70°C until analysis, which was within three months of collection. Identical supervision and standardization of analyses were conducted after T₁ and T₂ blood collections.

Sample analysis

For all assays in both periods, the variability of standards and standardized blood samples was within 10%. Serum ferritin, which reflects body iron stores [7, 8], was determined using an enzyme-linked immunosorbent assay (ELISA) purchased from New England Immunology Associates (Cambridge, Mass, USA). Haemoglobin and haematocrit were measured in the local clinic within 24 hours by standard techniques (cyanomethaemoglobin with electronic reading and centrifugation in capillary tubes). Red cell folate was determined by microbiological assay using L. casei, with ascorbate as a preservative, as described by Scott et al. [25]. Plasma retinol and carotene were determined with the micromethod of Neeld and Pearson [26], with modifications recommended by Arroyave et al. [27]. Carotene was determined to reflect dietary sources of provitamin A and antioxidant protection. In all, 466 blood samples were successfully taken. Among these, the analysis was spoiled because of insufficient sample or other reason for ferritin (1%), erythrocyte folate (8%), retinol (3%), carotene (2%), and haemoglobin (2%). The data presented are for 427 samples with all analyses completed.

TABLE 1. Participants by age and sex in assessments before (T₁) and after (T₂) intervention programme

Age (yr)	Sex	Number a		Repeat participants
		T1	T2
13-19	F	19	37	6
	M	20	30	7
20-40	F	41	60	20
	M	54	53	22
41-60	P	24	32	17
	M	22	27	18
>60	F	12	17	10
	M	7	11	7
Total		199	267	107

a. Not all participants gave sufficient sample for all analyses (see text).

Statistics

Values are expressed as means ± SEM. Differences in blood values within age and sex categories across the two assessment periods were tested by ANOVA and Student’s t test (SAS/STAT, Version 6, SAS Institute Inc., Cary, NC, USA). An alpha value of .05 was used in all statistical tests.

Results

Participants

During assessment periods T₁ and T₂, all participants for whom results are reported were registered members of the Nuxalk Nation and resident in Bella Coola, British Columbia. During the assessments (May 1983 and May 1986), approximately 500 persons were on the reserve. Table 1 shows the teenage and adult participants by age and sex in the periods before (T₁) and after (T₂) the intervention programme. Since mobility in and out of the reserve is well known and is recognized as a sampling concern, the number of repeating participants is also shown. The total number of participants was 199 at T₁ and 267 at T₂; 107 participated in both assessment periods. Upon request from the community, blood samples were not taken from pregnant or lactating women, or from children under 13 years of age.

Blood values

Tables 2 and 3 show blood values (mean ± SEM) by age, sex, and period. For females (table 2), significant improvements from T₁ to T₂ were shown for teenagers 13 to 19 years of age for carotene and folate, but not for retinol, ferritin, or haemoglobin. Young adult women 20 to 40 years of age demonstrated improvements in carotene and retinol; older women 41 to 60 years of age showed improvements in carotene, retinol, folate, and haemoglobin; and elders over 60 years of age had improved status for retinol and folate. For males (table 3) improvements in all age categories were shown for retinol. Carotene improved for those 13 to 19, 20 to 40, and 41 to 60 years of age. No improvement was seen in ferritin, folate, or haemoglobin. Summary values for adults of both sexes 20 to 60 years of age (thus excluding teenagers and elders) are given at the bottom of table 3. It is shown that improvements after the intervention period were made for carotene, retinol, and folate.

Table 4 compares the results for adults 20 to 60 years of age by sex. As expected, ferritin and haemoglobin levels were higher for men in both time periods. In the later time period (T₂) men had significantly more plasma retinol than women, but women had significantly more red cell folate than men. Table 5 shows that for all participants in both assessments (paired comparisons, p <.0001), blood levels of carotene, retinol, and folate significantly improved.

Table 6 shows the number of persons in age/sex groups whose blood values fell below established risk cut-off categories for retinol, ferritin, and red cell folate. As expected, there were few adult men at risk for low ferritin; however, among teenagers, 11 of 13 females (85%) and 9 of 18 males (50%) were at risk for low ferritin at T₁. This improved to 17% and 11%, respectively, at T₂. The greatest risks for these three indicators of nutritional status among females were ferritin and folate in teenagers, retinol and ferritin in young women 20 to 40 years of age, and retinol and folate in elders over age 60. Among males, the greatest risks were for ferritin and folate in teenagers, retinol and folate in young adult men, and retinol in older men (41-60 years). In considering the change in percentage of persons at risk from T₁ to T₂, two of the eight age/sex groups showed an increased percentage at risk for one nutrient: these were for folate in older men 41 to 60 years of age and for ferritin in young women 20 to 40 years of age. The remaining six age/sex groups showed decreased prevalence of risk for all three nutrients.

TABLE 2. Mean blood values (± SEM) for all females, by age and period ^a

Age (yr)	Period	N	b-Carotene (µg/dl)	Retinol (µg/dl)	Ferritin (ng/ml)	Red cell folate (ng/ml)	Haemoglobin (g/dl)
13-19	T1	13	42.3 ± 3.9	26.9 ± 6.9	16.3 ± 3.6	185 ± 15	12.6 ± 0.3
	T2	35	56.7 ± 5.2	34.4 ± 16.4	16.0 ± 2.1	285 ± 19	12.5 ± 0.2
			*	NS b	NS	*	NS
20-40	T1	41	37.0 ± 2.4	21.6 ± 0.07	25.4 ± 4.5	252 ± 20	12.8 ± 0.2
	T2	53	54.9 ± 2.3	34.8 ± 1.6	20.6 ± 2.6	298 ± 15	12.5 ± 0.2
			*	*	NS	NS	NS
41-60	T1	24	33.3 ± 3.0	25.1 ± 1.1	34.8 ± 8.2	212 ± 20	12.4 ± 0.4
	T2	27	47.3 ± 3.7	42.3 ± 2.5	35.3 ± 4.4	289 ± 20	13.2 ± 0.2
			*	*	NS	*	*
>60	T1	11	36.1 ± 3.0	22.4 ± 2.1	53.1 ± 11.1	186 ± 44	13.2 ± 0.5
	T2	13	33.2 ± 3.3	32.8 ± 2.4	51.5 ± 11.7	356 ± 52	13.1 ± 0.2
			NS	*	NS	*	NS

a. Normal values were assumed to be as follows: b-carotene >40 µg/dl; retinol >20 µg/dl; ferritin >10 ng/ml; red cell folate >60 ng/ml; female haemoglobin >11.5 g/dl if <17 yr and >12 g/dl if ³l7 yr; male haemoglobin >13 g/dl it <17 yr and >14 g/dl if ³17 yr.

b. NS, Not significant.

* p £ .05, t test.

TABLE 3. Mean blood values (± SEM) for all males, by age and period, and for males and females 20 to 60 years of age, by period

Age (yr)	Period	N	b-Carotene (µg/dl)	Retinol (µg/dl)	Ferritin (ng/ml)	Red cell folate (ng/ml)	Haemoglobin (g/dl)
Males
13-19	T1	18	40.4 ± 2.2	24.5 ± 1.2	19.4 ± 3.6	211 ± 17	14.6 ± 0.3
	T2	28	53.6 ± 2.7	38.5 ± 3.4	32.0 ± 6.6	242 ± 15	14.6 ± 0.2
			*	*	NS a	NS	NS
20-40	T1	51	40.1 ± 1.5	24.8 ± 0.7	59.2 ± 5.8	227 ± 9	14.7 ± 0.2
	T2	46	57.1 ± 3.3	47.4 ± 2.6	65.0 ± 6.9	243 ± 12	14.9 ± 0.1
			*	*	NS	NS	NS
41-60	T1	22	35.7 ± 3.2	24.4 ± 1.8	69.4 ± 10.5	185 ± 16	14.6 ± 0.3
	T2	27	53.4 ± 4.0	52.1 ± 4.6	61.0 ± 9.5	191 ± 16	14.6 ± 0.1
			*	*	NS	NS	NS
>60	T1	7	32.1 ± 4.5	21.9 ± 1.3	63.6 ± 11.5	197 ± 44	14.1 ± 0.5
	T2	11	43.0 ± 4.4	41.0 ± 4.0	57.9 ± 10.5	301 ± 30	14.6 ± 0.4
			NS	*	NS	NS	NS
Both sexes
20-60	T1	138	37.4 ± 1.2	23.8 ± 0.5	46.6 ± 3.6	226 ± 8	13.7 ± 0.1
	T2	153	54.1 ± 1.6	42.4 ± 1.4	42.8 ± 3.2	264 ± 8	13.7 ± 0.1
			*	*	NS	*	NS

a. NS, Not significant.
* p £ .05, t test.

TABLE 4. Mean blood values (± SEM) of persons 20 to 60 years of age by period and sex

Period	Sex	N	b-Carotene (µg/dl)	Retinol (µg/dl)	Ferritin (ng/ml)	Red cell folate (ng/ml)	Haemoglobin (g/dl)
T1	F	65	35.7 ± 1.9	22.8 ± 0.7	28.7 ± 4.1	238 ± 15	12.6 ± 0.2
	M	73	38.8 ± 1.4	24.6 ± 0.7	62.1 ± 5.1	214 ± 8	14.6 ± 0.1
			Ns a	NS	*	NS	*
T2	F	80	52.8 ± 2.0	37.1 ± 1.4	24.9 ± 2.4	295 ± 12	12.7 ± 0.1
	M	73	55.9 ± 2.6	49.0 ± 2.3	63.6 ± 5.5	225 ± 10	14.9 ± 0.1
			NS	*	*	*	*

a. NS, Not significant.
* p £ .05, t test.

TABLE 5. Mean blood values (± SEM) and differences in blood values (T₂-T₁) of persons aged 13 to over 60 years who participated in both periods

Value	N	T1	T2	T2-T1	p a
b-Carotene (µg/dl)	102	38.1 ± 1.4	60.0 ± 1.7	12.9 ± 1.5	£.001
Retinol (µg/dl)	101	23.9 ± 0.6	41.2 ± 1.8	17.3 ± 1.8	£.001
Ferritin (ng/ml)	104	41.0 ± 3.3	46.4 ± 3.9	5.5 ± 3.5	NS b
Red cell folate (ng/ml)	92	221.2 ± 11.5	267.8 ± 11.7	46.6 ± 13.2	£.001
Haemoglobin (g/dl)	104	13.7 ± 0.2	13.8 ± 0.2	0.1 ± 0.1	NS

a. Paired t test.
b. NS, not significant.

The ranges of actual values below the risk cut-offs in table 6 were the following: retinol, 2.3 to 19.6 µtg/dl, with three values falling below 10µg/dl; ferritin, 1.0 to 9.75 ng/ml, with 26 values falling below 5 ng/ml (all except one were females); red cell folate, 3.0 to 159.6 ng/ml, with 13 values falling below 100 ng/ml (subjects were of both sexes, and all except two were <40 years of age).

Discussion

This research demonstrated that a health promotion programme for indigenous people that emphasized traditional food resources improved status for several nutrients. Although nutrition interventions are usually targeted to single nutrients for ease of assessment, it is rare to find populations where single nutrient deficiencies exist. The more common condition is that multiple nutrient deficiencies exist when food resources are inadequate in quantity or quality [28]. Vitamin A, iron, and folate are three micronutrients that are frequently cited for deficiencies in adults, particularly women, in the developing world, which includes communities of indigenous peoples in North America [2, 5, 6, 29]. Nuxalk women were determined to be at risk for deficiency of these three nutrients by dietary assessments conducted in 1982 [9]. This was confirmed in the first evaluation period of the work reported here (?i) for both female and male teenagers and adults, with many persons having low blood levels of two or all three of these nutrients (table 6).

The health promotion programme implemented between 7i and T-i emphasized generally healthy lifestyles and an improved diet incorporating locally available traditional foods, including fish, fish oils, shellfish, game, berries, and green plants [11, 19, 23, 24]. Food items found in local stores were also included in the education activities. Many of the promoted food items were documented for their nutrient content, including retinol and iron; however, the folate contents of many of these traditional food items have not been determined [12,14-17, 30]. Programme activities emphasized work with women’s groups and schoolchildren; generally speaking, activities that engaged adult men, particularly those in the 40 to 60 age group, and all teenagers, were less easy to implement than those with women or elementary schoolchildren.

TABLE 6. Number (percentage) of persons at risk for retinol, ferritin, and folate deficiencies, by sex, age, and period ^a

Age (yr)	Period	N	Retinol	Ferritin	Red cell folate	2 or more micronutrients
Females
13-19	T1	13	4	11	8	5
	T2	35	3	6	4	4
20-40	T1	41	16	5	8	5
	T2	53	7	17	3	0
41-60	T1	24	4	4	2	2
	T2	27	0	3	2	0
>60	T1	11	4	1	5	2
	T2	13	1	2	1	1
Males
13-19	T1	18	4	9	6	4
	T2	28	4	3	4	3
20-40	T1	51	10	3	9	2
	T2	46	1	1	3	0
41-60	T1	22	7	0	8	2
	T2	27	0	1	12	0
>60	T1	7	2	0	2	1
	T2	11	0	0	1	0
Total	T1	187	51 (27)	33 (18)	48 (26)	23 (12)
	T2	240	16 (7)	33 (14)	30 (13)	8 (3)

a. See text and tables 2 and 3 for values. Risk cut-offs: retinol <20 µg/dl; ferritin <10 ng/ml; folate <160 ng/ml.

In many Canadian aboriginal communities (First Nations, Inuit, or Metis Peoples), protein intake is high because fishing and hunting are still traditionally practised. Plant foods, such as berries, leafy plants, and roots, that traditionally complemented a diet in which the major source of energy was from animal food are less commonly used. Market food imported into aboriginal communities has been documented to provide ample carbohydrates and fats, particularly saturated fat, but minimal amounts of micronutrients [2, 4, 29]. Therefore, it was not unexpected that vitamin A and folate status was initially low. It was also expected that teenagers and the elderly would have diets with more nutrients at risk than young and middle-aged adults because of changing physiological status and lack of attention to diet.

Women in the child-bearing years are the usual target for assessments of these three nutrients in public health programmes in developing areas. Young children are also recipients of micronutrient improvement programmes, particularly for vitamin A and iron [31]. This report demonstrates that teenagers of both sexes and adult men were also at risk for deficiency of these nutrients and benefited from the nutrition improvement programme. It is of interest, although unexplainable, that women improved more in folate and men improved more in retinol (table 4). Worthy of note is that traditionally and presently men are more engaged in the harvest, preparation, and consumption of fish and fish oils, which are known sources of retinol (e.g., ooligan grease; see refs. 12 and 30), whereas women had more responsibility for harvest and preparation of local berries and other plant foods likely to be sources of folate. Although sharing of traditional food is common within extended families and the community, men tend to eat more fish and oil than women, and women tend to eat more salads and fruits than men.

The interactive effects of retinol, iron, and folate have been noted earlier. Simultaneous deficiencies of retinol and iron have been reported in Ethiopia and Guatemala [32, 33], and concerns for dual deficiencies of folate and iron have been reported in lactating Canadian women [34]. Thus, the lack of all three nutrients in the same population presents a serious concern for health status, especially when supplements of all three are not usually present in one vehicle that would be readily accepted by people of all ages and both sexes. A health promotion programme emphasizing the use of food for the entire community is the most feasible way to approach this kind of multiple nutritional status problem involving several nutrients for males and females of all ages.

There has been very little documentation of successful nutrition interventions with natural (i.e., non-fortified) locally available food to improve nutrient deficiencies in developing regions. The most recent successes for nutrients reported here have been for vitamin A and folate (one report) [31, 35-39]. Thus, research with the Nuxalk can be noted for its success in improving status with a food-based health promotion programme simultaneously for vitamin A, folate, and, to a limited extent, iron.

During the time when the Nuxalk Food and Nutrition Program [23] was implemented, it was the only nutrition improvement programme in the community. Economic conditions remained stable, apart from normal rates of inflation, and unemployment and seasonal employment did not change noticeably during the programme. A variety of activities promoted the use of nutrient-rich traditional and market food and other healthy lifestyle changes. Programme personnel were successful in encouraging the only food outlet in the area at the time (the Coop) to stock more fruits and vegetables at cost and to encourage the increased use of a variety of traditional food items, particularly fish and wild fruit. Nutrient supplements, which included retinol, folate, and iron, were routinely provided to pregnant and lactating women, and supplements for pre-school children were available from the health centre. Teenagers and adults, except for pregnant or lactating women, were not provided with supplements or encouraged to take them. Nevertheless, it was not unusual that a variety of “health food” supplements were purchased in urban centres and used by some adult members of the community. No attempt was made to prevent these persons from participating in the study. To our knowledge, there were no other community programmes that would have altered retinol, folate, or iron status.

The techniques used in this evaluation were standardized assays current at the initiation of the programme in 1983. Although more recent techniques for determining retinol and folate levels in blood may have been more precise, it was important to use the same assays in both evaluation periods. This may be viewed as a limitation, albeit an unavoidable one, in this report. Nevertheless, by using different methods of data analysis, unpaired and paired comparisons, independent and grouped comparisons, as well as proportions of the various age/sex groups at risk, we were able to show consistently that retinol, carotene, and folate levels improved for the community at large and that ferritin levels improved in teenagers.

It is concluded that overall community status for vitamin A and folate improved, and that iron status for teenagers improved, after an intervention programme that stressed the use of locally available, culturally important food for the people of the Nuxalk Nation.

Acknowledgements

Support is acknowledged from Health and Welfare Canada for Health Promotion Contribution 6554-2-28 and NHRDP Grant 6610-1313-44. We express our appreciation to those involved in the implementation and evaluation of the Nuxalk Food and Nutrition Program. In particular, we thank the project officers of the Health Promotion Contribution Program, Margo Palmer, and of the National Health Research and Development Program, Roy Sampson, for their continued encouragement throughout this lengthy programme. For their diligence in work on the programme from the health clinic of the Nuxalk Nation, we express sincere appreciation to Rose Hans, Louise Hilland, Emily Schooner, Debbie Tallio, and Grace Hans, as well as to many elders who gave their knowledge and support, without which this programme could not have begun. We give special thanks to Chief Ed Moody, Chief Archie Pootlass, and the other councillors from the administrative centre of the Nuxalk Nation, who gave their advice and support during the programme, which extended from 1983 to 1988. For laboratory, computer, administrative, and educational support, we are appreciative to Mitch Ericson, Patricia Thorn, Agdas Zamani, Rula Soueida, Sandra Marquis, Glory Froese, Frank Flynn, Hugh Brody, Dr. Wendy Wolfe, Dawn Loewen, and Dr. Nancy Turner. We also express our appreciation to many graduate and undergraduate students who assisted in various aspects of the programme and its evaluation. Dr. Olivier Receveur and other, anonymous reviewers are appreciated for critical reviews of the manuscript.

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