Biomedical subjects

S F Knutsen

Publications and source records attributed to S F Knutsen.

At least 19 recordsLinked to original sources

PubMed2001

Comparing biological measurements of vitamin C, folate, alpha-tocopherol and carotene with 24-hour dietary recall information in nonhispanic blacks and whites.

PURPOSE: To assess intake of several vitamins in preparation for a large cohort study investigating the effect of diet on risk of colon and prostate cancer. METHODS: The dietary intake of several vitamins were assessed using eight different 24-hour recalls and a 200-item food frequency questionnaire (FFQ) from each subject. Participants also attended a clinic where blood was drawn and body composition, weight, height, and blood pressure were measured. A total of 97 black and 96 nonhispanic white subjects participated. The levels of alpha-tocopherol, carotene, folate, and vitamin C in the blood were correlated with the dietary intakes as measured by both 24-hour recalls and FFQ. RESULTS: Correlations between blood levels and energy-adjusted dietary intake assessed by 24-hour recalls (with supplements) were as follows: carotene (adjusted for serum cholesterol): 0.47 and 0.55 in black and white subjects, respectively; alpha-tocopherol (adjusted for serum cholesterol): 0.61 (blacks) and 0.50 (whites); vitamin C: 0.22 (blacks) and 0.17 (whites); folate: 0.54 (blacks) and 0.55 (whites). Correlations between blood levels and FFQ indices were smaller in magnitude: 0.34 and 0.28 for carotene in black and white subjects, respectively, 0.37 and 0.56 for alpha-tocopherol (adjusted for serum cholesterol), 0.20 and 0.03 for vitamin C and 0.24 and 0.32 for folate. CONCLUSIONS: The correlations observed were generally of modest to moderate size and were similar to or larger than those reported by others. This is despite variations in absorption, metabolism, and excretion of the vitamins and suggests that both the 24-hour recalls and the FFQ contain valid information.

Black or African American↗

PubMed2001

Validity of a physical activity questionnaire among African-American Seventh-day Adventists.

INTRODUCTION: Physical activity has been identified as an important predictor of chronic disease risk in numerous studies in which activity levels were measured by questionnaire. Although the validity of physical activity questionnaires has been documented in a number of studies of U.S. adults, few have included a validation analysis among blacks. We have examined the validity and reliability of a physical activity questionnaire that was administered to 165 black Seventh-day Adventists from Southern California. METHODS: Subjects completed a self-administered physical activity questionnaire and then "reference" measures of activity (7-d activity recalls, pedometer readings) and fitness (treadmill test) were completed in subsets of this population. RESULTS: The authors found that 7-d recall activity levels correlated well with the corresponding questionnaire indices among women (total activity, r = 0.65; vigorous, r = 0.85; moderate, r = 0.44; inactivity, r = 0.59; sleep duration, r = 0.52) and men (total activity, r = 0.51; vigorous, r = 0.65; moderate, r = 0.53; inactivity, r = 0.69; sleep duration, r = 0.39). Vigorous activity from 7-d recalls was best measured by gender-specific indices that included only recreational activities among men and emphasized nonrecreational activities among women. Correlations between questionnaire data and the other "reference" measures were lower. Test-retest correlations of questionnaire items over a 6-wk interval were high (r = 0.4-0.9). CONCLUSION: Simple questions can measure activities of different intensity with good validity and reliability among black Adventist men and women.

Adult↗

PubMed2000

Urinary 1-methylhistidine is a marker of meat consumption in Black and in White California Seventh-day Adventists.

Meat consumption predicts risk of several chronic diseases. The authors validate the accuracy of meat consumption reported by food frequency questionnaires and the mean of eight 24-hour recalls, using urinary methylhistidine excretion, in 55 Black and 71 White Adventist subjects in Los Angeles and San Diego, California, in 1994-1997. 1-Methylhistidine excretion predicts vegetarian status in Black (p = 0.02) and in White (p = 0.005) subjects. Spearman's correlation coefficients between 1-methylhistidine and estimated meat consumption were usually between 0.4 and 0.6 for both food frequency questionnaires and 24-hour recall data. This is despite the chance collection of dietary recalls and urines from omnivores on meatless days.

Black or African American↗

PubMed1999

Age at natural menopause and total mortality and mortality from ischemic heart disease: the Adventist Health Study.

We studied the relationship between age at natural menopause and total mortality as well as mortality from ischemic heart disease in a cohort of 6182 California Seventh-Day Adventist women who reported a natural menopause. During follow-up from 1976 through 1988, there were 1831 deaths. A total of 308 deaths due to ischemic heart disease occurred in women who denied ischemic heart disease at start of follow-up. An early menopause was associated with increased total mortality (P value for linear trend <0.001) and ischemic heart disease mortality (P value for linear trend = 0.03). This relationship could not be explained by possible confounding variables. Our results support the hypothesis that an early natural menopause (35-40 years old) increases the risk of ischemic heart disease. There is, however, also some evidence of increased risk of ischemic heart disease in women with a very late menopause (>55 years), particularly in women who never have used postmenopausal estrogens.

Adult↗

PubMed1999

Long-term inhalable particles and other air pollutants related to mortality in nonsmokers.

Long-term ambient concentrations of inhalable particles less than 10 microm in diameter (PM10) (1973- 1992) and other air pollutants-total suspended sulfates, sulfur dioxide, ozone (O3), and nitrogen dioxide-were related to 1977-1992 mortality in a cohort of 6,338 nonsmoking California Seventh-day Adventists. In both sexes, PM10 showed a strong association with mortality for any mention of nonmalignant respiratory disease on the death certificate, adjusting for a wide range of potentially confounding factors, including occupational and indoor sources of air pollutants. The adjusted relative risk (RR) for this cause of death as associated with an interquartile range (IQR) difference of 43 d/yr when PM10 exceeded 100 microg/m3 was 1.18 (95% confidence interval [CI]: 1.02, 1.36). In males, PM10 showed a strong association with lung cancer deaths-RR for an IQR was 2.38 (95% CI: 1.42, 3.97). Ozone showed an even stronger association with lung cancer mortality for males with an RR of 4.19 (95% CI: 1.81, 9.69) for the IQR difference of 551 h/yr when O3 exceeded 100 parts per billion. Sulfur dioxide showed strong associations with lung cancer mortality for both sexes. Other pollutants showed weak or no association with mortality.

Adult↗

PubMed1999

Respiratory symptoms and pulmonary function in an elderly nonsmoking population.

OBJECTIVE: To examine risk factors for chronic airway disease (CAD) in elderly nonsmokers, as determined by pulmonary function tests (PFTs), and to correlate reported respiratory symptoms with PFT measures. DESIGN: An observational survey. SETTING: Several communities in California. MEASUREMENTS: Exposures and respiratory history were assessed by standardized questionnaire. PFTs were performed and prediction equations derived. RESULTS: Significant risk factors for obstruction on PFTs in multiple logistic regression included reported environmental tobacco smoke (ETS) exposure (relative risk [RR]=1.44), parental CAD or hay fever (RR=1.47), history of childhood respiratory illness (RR=2.15), increasing age, and male sex. The number of years of past smoking was of borderline significance (RR=1.29 for 10 years of smoking; p=0.06). The prevalence of obstruction on PFTs was 24.9% in those with definite symptomatic CAD, compared with 7.5% in those with no symptoms of CAD. The prevalence of obstruction was 36.0% among those with asthma and 70.6% among those with emphysema. Also, symptomatic CAD correlated with reduction in lung function by analysis of covariance. The mean percent predicted FEV1 adjusted for covariates was 90.6% in persons with definite symptoms of CAD, compared with 97.8% in those without it (p < 0.001). CONCLUSIONS: Age, sex, parental history, childhood respiratory illness, and reported ETS exposures were significant risk factors for obstruction on PFTs. Self-reported respiratory symptoms also correlated significantly with PFTs.

Adult↗

PubMed1998

Validity of dietary recall over 20 years among California Seventh-day Adventists.

Past dietary habits are etiologically important to incident disease. Yet the validity of such measurements from the previous 10-20 years is poorly understood. In this study, the authors correlated food frequency results that were obtained in 1994-1995 but pertained to recalled diet in 1974 with the weighted mean of five random 24-hour dietary recalls obtained by telephone in 1974. The subjects studied were 72 Seventh-day Adventists who lived within 30 miles of Loma Linda, California; had participated in a 1974 validation study; were still alive; and were willing to participate again in 1994. A method was developed to allow correction for random error in the reference data when these data had differentially weighted components. The results showed partially corrected correlation coefficients of greater than 0.30 for coffee, whole milk, eggs, chips, beef, fish, chicken, fruit, and legumes. Higher correlations on average were obtained when the food frequencies were scored simply 1-9, reflecting the nine frequency categories. The 95% confidence intervals for 15 of the 28 correlations excluded zero. Incorporation of portion size information was unhelpful. The authors concluded that in this population, data recalled from 20 years ago should be treated with caution but, for a number of important foods, that the degree of validity achieved approached that obtained when assessing current dietary habits.

California↗

PubMed1998

Spirometric reference equations for older adults.

The objective of this study was to develop spirometric reference equations for healthy, never-smoking, older adults. It was designed as a cross-sectional observational study consisting of 1510 Seventh Day Adventists, ages 43-79 years enrolled in a study of health effects of air pollutants. Individuals were excluded from the reference group (n = 565) for a history of current respiratory illness, smoking, or chronic respiratory disease, and for a number of 'non-respiratory' conditions which were observed in these data to be related to lower values of FEV1. Gender-specific reference equations were developed for the entire reference group and for a subset above 65 years of age (n = 312). Controlling for height and age, lung function was found to be positively related to the difference between armspan and height, and in males was found to be quadratically related to age. The predicted values for this population generally fell within the range of those of other population groups containing large numbers of adults over the age of 65 years. Individuals with lung function below the 5th percentile in this sample, however, could not be reliably identified by using the lower limits of normal predictions commonly used in North America and Europe.

Adult↗

PubMed1998

Does high soy milk intake reduce prostate cancer incidence? The Adventist Health Study (United States)

OBJECTIVES: Recent experimental studies have suggested that isoflavones (such as genistein and daidzein) found in some soy products may reduce the risk of cancer. The purpose of this study was to evaluate the relationship between soy milk, a beverage containing isoflavones, and prostate cancer incidence. METHODS: A prospective study with 225 incident cases of prostate cancer in 12,395 California Seventh-Day Adventist men who in 1976 stated how often they drank soy milk. RESULTS: Frequent consumption (more than once a day) of soy milk was associated with 70 per cent reduction of the risk of prostate cancer (relative risk = 0.3, 95 percent confidence interval 0.1-1.0, p-value for linear trend = 0.03). The association was upheld when extensive adjustments were performed. CONCLUSIONS: Our study suggests that men with high consumption of soy milk are at reduced risk of prostate cancer. Possible associations between soy bean products, isoflavones and prostate cancer risk should be further investigated.

Adult↗

PubMed1998

Long-term particulate and other air pollutants and lung function in nonsmokers.

The associations between lung function measures (spirometry and peak expiratory flow lability) and estimated 20-yr ambient concentrations of respirable particles, suspended sulfates, sulfur dioxide, ozone, and indoor particles were studied in a sample of 1,391 nonsmokers followed since 1977. Differences in air pollutants across the population were associated with decrements of lung function. An increase of 54 d/yr when particles < 10 micro(m) in diameter (PM10) exceeded 100 microg/m3 was associated with a 7.2% decrement in FEV1, as percent of predicted, in males whose parents had asthma, bronchitis, emphysema, or hay fever and with increased peak expiratory flow lability of 0.8% for all females and 0.6% for all males. An increase in mean SO4 concentration of 1.6 microg/m3 was associated with a 1.5% decrement in FEV1, as percent of predicted, in all males. An increase of 23 ppb of ozone as an 8-h average was associated with a 6.3% decrement in FEV1, as percent of predicted, in males whose parents had asthma, bronchitis, emphysema, or hay fever.

Adult↗

PubMed1998

Long-term concentrations of ambient air pollutants and incident lung cancer in California adults: results from the AHSMOG study.Adventist Health Study on Smog.

The purpose of this study was to evaluate the relationship of long-term concentrations of ambient air pollutants and risk of incident lung cancer in nonsmoking California adults. A cohort study of 6,338 nonsmoking, non-Hispanic, white Californian adults, ages 27-95, was followed from 1977 to 1992 for newly diagnosed cancers. Monthly ambient air pollution data were interpolated to zip code centroids according to home and work location histories, cumulated, and then averaged over time. The increased relative risk (RR) of incident lung cancer in males associated with an interquartile range (IQR) increase in 100 ppb ozone (O3) was 3.56 [95% confidence interval (CI), 1.35-9.42]. Incident lung cancer in males was also positively associated with IQR increases for mean concentrations of particulate matter <10 microm (PM10; RR = 5.21; CI, 1.94-13.99) and SO2 (RR = 2.66; CI, 1.62-4.39). For females, incident lung cancer was positively associated with IQR increases for SO2 (RR = 2.14; CI, 1.36-3.37) and IQR increases for PM10 exceedance frequencies of 50 microg/m3 (RR = 1.21; CI, 0.55-2.66) and 60 microg/m3 (RR = 1.25; CI, 0.57-2.71). Increased risks of incident lung cancer were associated with elevated long-term ambient concentrations of PM10 and SO2 in both genders and with O3 in males. The gender differences for the O3 and PM10 results appeared to be partially due to gender differences in exposure.

Adult↗

PubMed1997

[Shortage of physicians, leave of absence because of pregnancy and child care. A survey of physicians 1993].

The shortage of physicians is still a problem in Norway. In 1992, 344 (3.1%) physician full time equivalents (FTE) were "lost" because of family leave. Maternity leave averaged 34.7 weeks. 26% of the physicians who became a father in 1992 took an average of three weeks paternity leave. Leaves related to other family responsibilities seem to be increasing among male physicians. Our estimates show that interruption of career, along with female physicians who choose to work shorter hours, will represent a discount of 452 (3.3%) physician FTEs in year 2002. If Norwegian physicians increase their leaves of absence in line with the possibilities provided by government regulations, this number will be even larger (4.5%). Changes in the pattern of career interruption should be considered when projecting the supply of physicians.

Adult↗

PubMed1994

Lifestyle and the use of health services.

In 1976, 27,766 Seventh-day Adventists answered questions on diet, medications, use of health services, and prevalence of disease. Approximately 55% (n = 15,228) were vegetarians. Compared with vegetarian females, nonvegetarian females reported significantly more overnight hospitalizations and surgeries during the past year and nonvegetarian males reported more overnight hospitalizations and x-rays. The average numbers of chronic diseases were 1.24 in nonvegetarian females and 1.03 in vegetarian females compared with 0.93 and 0.79 in nonvegetarian and vegetarian males, respectively. Nonvegetarian females also reported more chemical allergy (rate ratio (RR) = 1.30), asthma (RR = 1.24), drug allergy (RR = 1.17), beesting allergy (RR = 1.17), and hayfever (RR = 1.15). Only chemical and drug allergy were more prevalent in nonvegetarian males. Medication use was increased by 70-115% in nonvegetarian females and more than doubled in nonvegetarian males. We conclude that a vegetarian diet may decrease the prevalence of chronic disease, medication use, and health service use, and thus, potentially, health care costs.

Chronic Disease↗

PubMed1993

Effects of walnuts on serum lipid levels and blood pressure in normal men.

BACKGROUND: In a recent six-year follow-up study, we found that frequent consumption of nuts was associated with a reduced risk of ischemic heart disease. To explore possible explanations for this finding, we studied the effects of nut consumption on serum lipids and blood pressure. METHODS: We randomly placed 18 healthy men on two mixed natural diets, each diet to be followed for four weeks. Both diets conformed to the National Cholesterol Education Program Step 1 diet and contained identical foods and macronutrients, except that 20 percent of the calories of one diet (the walnut diet) were derived from walnuts (offset by lesser amounts of fatty foods, meat, and visible fat [oils, margarine, and butter]). RESULTS: With the reference diet, the mean (+/- SD) serum values for total, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) cholesterol were, respectively, 182 +/- 23, 112 +/- 16, and 47 +/- 11 mg per deciliter (4.71 +/- 0.59, 2.90 +/- 0.41, and 1.22 +/- 0.28 mmol per liter). With the walnut diet, the mean total cholesterol level was 22.4 mg per deciliter (0.58 mmol per liter) lower than the mean level with the reference diet (95 percent confidence interval, 28 to 17 mg per deciliter [0.72 to 0.44 mmol per liter]); the LDL and HDL cholesterol levels were, respectively, 18.2 mg per deciliter (0.47 mmol per liter) (P < 0.001) and 2.3 mg per deciliter (0.06 mmol per liter) (P = 0.01) lower. These lower values represented reductions of 12.4, 16.3, and 4.9 percent in the levels of total, LDL, and HDL cholesterol, respectively. The ratio of LDL cholesterol to HDL cholesterol was also lowered (P < 0.001) by the walnut diet. Mean blood-pressure values did not change during either dietary period. CONCLUSIONS: Incorporating moderate quantities of walnuts into the recommended cholesterol-lowering diet while maintaining the intake of total dietary fat and calories decreases serum levels of total cholesterol and favorably modifies the lipoprotein profile in normal men. The long-term effects of walnut consumption and the extension of this finding to other population groups deserve further study.

Adult↗

PubMed1993

A comparative study of serum selenium and vitamin E levels in a population of male risk drinkers and abstainers. A population-based matched-pair study.

Depressed selenium and Vitamin E levels may contribute to hepatic injury through lipid peroxidation. To study the effect of moderate alcohol drinking (32.4 +/- 23.6 g ethanol/d) on serum selenium and serum vitamin E concentrations, we conducted a matched-pair study of 73 healthy, well-nourished risk drinkers and healthy controls with little or no alcohol consumption. Among risk drinkers, serum selenium was significantly lowered (1.49 vs 1.67 mumol/L; p < 0.001) compared with controls. Difference in alpha-tocopherol concentrations did not, however, reach statistical significance (22.8 vs 24.9 mumol/L; p = 0.06). Nutritional and life-style factors differed very little between the two groups. We conclude that even moderate alcohol consumption lowers selenium status. Selenium may thus represent a link joining the hepatotoxic and nutritional backgrounds of alcoholic liver disease.

Adult↗

PubMed1991

The Tromsø Survey: the Family Intervention study--the effect of intervention on some coronary risk factors and dietary habits, a 6-year follow-up.

While most intervention studies on coronary heart disease have focused on the high-risk person only, the present study used the family as the unit of intervention. In the study 1373 high-risk men, ages 30-54 years, were identified on the basis of high total cholesterol (TC) and/or low relative high-density lipoprotein cholesterol (HDL-C) (HDL-C/TC) following the 1979/1980 survey in Tromsø. The men and their families were randomly allocated to a control or intervention condition. The intervention families were given advice on diet, smoking, and exercise. At rescreening in 1986/1987, significantly lower risk factor levels were found in both the intervention men and their spouses compared with those in the control group. For children, the differences were small and mostly nonsignificant. Men, spouses, and children in the intervention group reported more favorable dietary habits than those in the control group. No differences were found in smoking or leisure time physical activity.

Adolescent↗

PubMed1991

Cardiovascular risk factor levels in ethnic Hawaiians.

We report a cardiovascular risk factor survey of "native" Hawaiians 20-59 years old (70 percent, or 257), living on the Hawaiian Homestead lands on the island of Molokai, Hawaii. More than 60 percent of both sexes were overweight. Among males, 42 percent were smokers. The percent of the population with systolic blood pressure greater than 140 mm Hg or a diastolic pressure greater than 90 mm Hg or taking hypertensive medications was 14 percent of those ages 20-39 and 36 percent of those ages 40-59. The percent with serum cholesterol greater than or equal to 6.2 mmol/L ranged from 8 percent of those 20-29 years old to 46 percent in those 50-59 years old. Two percent of those ages 20-29 had a history of diabetes, or 2 + or greater glycosuria by dipstick, as did 23 percent of those ages 50-59. The majority of the known diabetics exhibited glycosuria and elevated glycohemoglobin levels, indicating poor control. Hypertension, although usually known to the participant, was frequently uncontrolled. From these data, it appears that among this group of Hawaiians major risk factors for cardiovascular disease were frequent, while at the same time the levels of awareness and/or control for most of these factors were low.

Adult↗

PubMed1990

Wives of coronary high-risk men--are they also at higher risk? The Tromsø Heart Study.

Blood lipids, blood pressure, body mass index (BMI), smoking, dietary and exercise habits were studied in 911 wives of men with high risk for coronary heart disease (CHD). Following the 1979/80 Tromsø Survey, 1373 men, aged 30-54 years, were identified as having high risk for CHD (HDL-cholesterol/total cholesterol less than or equal to 17.6% and/or total cholesterol greater than or equal to 7.86 mmol l-1). Of the 1373 men, 911 individuals had wives who also attended the screening. These wives were compared to age-matched, married women in the general population. A significantly higher total cholesterol level (5.98 mmol l-1 vs. 5.78 mmol l-1), lower HDL-cholesterol/total cholesterol (30.01% vs. 31.58%), higher BMI and higher coronary risk score (4.55 vs. 3.82) was found among the wives of the high-risk men. Furthermore, a higher proportion of these individuals were daily cigarette smokers (47.3% vs. 42.1%), and had received fewer years of education. They also had more dietary habits associated with increased risk of CHD than other married women in the general population. Our findings support the hypothesis that members of the same household as a person with increased risk for CHD also have increased risk. This is most probably due to shared lifestyle.

Adult↗