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United States Department of Agriculture

Agricultural Research Service

 

 

 

 

 

Ph.D., Department of Kinesiology

University of Illinois
 

Office: 430 West Health Science Drive

            University of California

            Davis, CA 95616

 

Phone: (530) 752-4160

             (530) 754-4376

          

                                        Van Loan Lab

                                                                                                                   

Marta Van Loan

 

Research Program

 

My most recent research has focused on 1) the role of dairy foods to reduce postmenopausal bone loss, modulate weight loss, and attenuate weight-loss induced bone loss and 2) the effect of different dietary components including saturated fats on postprandial inflammation and immune response which in turn can be detrimental to bone health.

 

 

Biography

      

A native of West Springfield, Massachusetts, Dr. Van Loan obtained a Ph.D. degree in 1985 in exercise physiology from the University of Illinois, Urbana, IL.

As a Research Assistant at the University of Illinois, Dr. Van Loan received extensive training in a full range of body composition methodologies from whole body 40K counting to skinfolds and underwater weighing.  She left Urbana, IL. in 1982 to assume a position with the  newly created USDA Western Human Nutrition Research Center (WHNRC) in San Francisco, CA.  Dr. Van Loan's responsibilities at the new Center included the development of a body composition laboratory for the assessment of nutritional status.

At the WHNRC, her primary focus has been on the development and validation of new body composition methodologies.  She has conducted numerous studies to validate methods such as total body electrical conductivity (TOBEC), bioelectrical impedance analysis (BIA), dual energy xray absorptiometry, (DXA), and bioelectrical impedance spectroscopy (BIS).  More recently her research interests have shifted to the influence of eating behaviors and dietary patterns on bone integrity and weight loss.  She has published over 70 related articles in scientific journals and textbooks.

Dr. Van Loan serves as a peer reviewer for numerous scientific journals such as the Journal of Applied Physiology, Medicine and Science in Sports and Exercise, and the American Journal of Clinical Nutrition.  In addition to her work as a peer reviewer, Dr. Van Loan is a Fellow in the American College of Sports Medicine and the Human Biology Council.  She has served as a member of the Program Planning Committee for the 1994 Nutrient Requirements and Functional Endpoints Meeting as well as for the 1998 Annual Meeting of the American Society for Clinical Nutrition and the 2006 and 2007 annual meeting of the American College of Sports Medicine.

 

 

Research Objectives

 

To determine the three-year efficacy of isoflavone-rich soy extract in attenuating bone loss in postmenopausal women. The central hypothesis is that soy isoflavones will attenuate bone loss in early postmenopausal women by maintaining bone formation, modulated by growth factors and isoflavone metabolism. The rationale for this research is that current hormone therapy is fraught with side effects that adversely affect women, resulting in non-compliance. This randomized double-blind placebo controlled clinical trial is designed to examine the effects of two doses (80 or 120 mg/d) of isoflavone-rich soy extract on bone in non-osteoporotic early postmenopausal women (N=280). Specific Aims are to:  1) Determine the bone-preserving effects of isoflavones on bone mass and on serum markers of bone turnover; 2) Identify potential mechanisms of the effects of isoflavones in preventing bone loss and in modulating bone turnover by measuring endogenous estrogens, sex hormone-binding globulin, follicle stimulating hormone, and insulin-like growth factor-I (IGF-I) and its binding protein; 3) Evaluate the extent to which individual variability in isoflavone metabolism influences the effects of isoflavones on bone. Changes in bone mass and serum bone markers will be the primary bone outcomes. Multiple regression analysis will be used for each outcome to estimate the treatment effects, while accounting for ethnic group, customary intake of soy, bone biomarkers, baseline bone mass, reproductive hormones, IGF-I and its binding protein, circulating isoflavones, and other factors known to affect bone mass. This study will provide valuable data to help elucidate the mechanisms by which isoflavones impact bone in postmenopausal women, contributing to our understanding of isoflavones as an alternative to traditional hormone therapy.  This study is presently in the third year of intervention with the last research cohort expected to complete the 3 year intervention in May 2008.

 

To determine how inclusion of 3 or more servings of dairy per day in a calorie-restricted diet changes the amount of visceral adiposity in overweight and obese subjects.  We are also conducting unique studies to evaluate the potential mechanism(s) by which dairy promotes weight and fat loss during dieting, through an examination of adipocyte size, gene expression, and inflammatory markers.  The hypotheses under investigation are (1) that inclusion of dairy foods in a modest energy restricted diet will significantly increase body fat loss compared to a control diet; (2) that dairy products in a modest energy restricted diet will result in greater fat loss from intra-abdominal adipose tissue compared to the control, 3) components of dairy products up- or down-regulate the secretion of metabolically-relevant hormones during the postprandial and inter-meal periods, 4) dairy products will promote satiety and/or satiation, 5) dairy foods reduce adipocyte differentiation and/or enhance adipocyte apoptosis, leading to concomitant white adipose tissue (WAT) expression changes for genes playing a role in these processes,  6) dairy foods will reduce adipocyte lipid storage and enhance pathways associated with thermogenesis and mitochondrial function in WAT, as reflected in gene expression changes and reduced adipocyte size, and 7) dairy foods included in a modest energy restricted diet will decrease inflammation in WAT and other tissues, thus decreasing circulating cytokines, improving zinc status, reducing expression of inflammatory markers in WAT, and reducing WAT macrophage infiltration.   In this project more than 60 research volunteers will be fed a diet with either 1 or less serving of dairy foods per day or 3 or more servings of milk, yogurt and cheese daily for 12 weeks.  Anticipated completion is December 2008.

 

 

Research Accomplishments

 

My research has focused on several areas – body composition methods development, bone metabolism, and various dietary interventions that affect bone metabolism. 

Accomplishments in the area of body composition methodology include the development and validation to total body electrical conductivity (TOBEC) to measure total body water, fat-free mass and body fat.  This conductivity research led in the validation of bioelectrical impedance analysis (BIA) as a portable, non-invasive technique for assessment total body water (TBW) as well as intra- and extra-cellular fluid (ICF, ECF) in healthy children and adults as well as in a variety of groups such as overweight and obese people, in clinical patients like pregnant women and HIV+ individuals.  This technology lends itself to use in field settings and has been used to assessment body composition of HIV+ women in South Africa as well as for monitoring changes in TBW, ICF and ECF in ultra-endurance athletes.  The ability to monitor changes in fluid balance has implications for electrolyte balance in a variety of conditions such as with renal dialysis patients.

Research conducted in my lab has shown that bone mineral content is not lost during weight lose when adequate nutrition is provided.  However, changes in body weight can affect the ability to accurately measures bone mineral density and that consideration must be given to the change in the size of the bone area measured.  Further research on bone density has included the examination of dieting behavior on bone density.  We demonstrated that women with above average dietary restraint scores, the process of controlling your food intake in order to control your weight, even though they are normal body weight for height have significantly lower bone mineral in their skeleton than women with average or below average restraint scores.  While dieting may be good for controlling increases in body weight it also impacts bone.  In a study of obese adult women, average age of 38 yrs., with histories of chronic dieting behavior we showed that repeated episodes of weight loss of 20, 30 or 40 pounds resulted in 1/3 of the women having a bone density classification of osteopenia (low bone mass) or osteoporosis at an age when bone density should be normal and stable.

In clinical research in the area of bone metabolism with cancer metastasis, specifically prostate cancer, we have demonstrated that markers of bone metabolism like n-telopeptide (N-Tx) can serve as a prognostic indicator of progression-free survival.  This research led to a multi-center National Cancer Institute (NCI) clinical study with approximately 900 patients in over 300 cancer centers throughout the country participating.  We are furthering our investigation into the diagnostic and prognostic abilities of bone metabolism to monitor patient response to cancer therapies.

I have also conducted a phase II NIH clinical trial to examine the role of soy isoflavones to reduce bone loss in postmenopausal women.  This project included 244 postmenopausal women from northern California and Iowa who participated in a 3-year study in which extract soy isoflavones where given in tablet form.  Results showed no benefit of the low dose (80mg/d) in reducing bone loss, however, a modest effect was found at the higher dose of 120 mg/d when included with lifestyle factors.  Overall, our findings suggest that the use of extracted soy isoflavones is of limited benefit in reducing bone loss in postmenopausal women.  This study also demonstrated that moderate levels of physical activity, an average 30 min/d, did contribute significantly to the current bone mineral density (BMD) of these postmenopausal women. 

Most recently we completed a 15-week controlled feeding study to examine the role of dairy foods to enhance central fat and weight loss during moderate energy restriction in overweight and obese adults. Seventy-one healthy, but overweight or obese, women and men who habitually were non-dairy consumers were enrolled.  Individuals were randomly assigned to either a low dairy intake moderate energy restricted diet (less than 1 serving of dairy/day) or adequate dairy intake (3-4 servings/day) incorporated into the energy restricted diet.  Participants were measured for resting metabolic rate, body composition, fat tissue biopsies, CT scan to measure intra-abdominal adipose tissue as well as a number of markers of endocrine hormones and inflammation.  We reported our primary findings at the annual meeting of Experimental Biology in April 2010 which included results on weight and fat loss as well as changes in adipose tissue macrophage infiltration and markers of inflammation.  We found no added benefit of 3-4 servings of dairy foods for increasing weight or fat loss compared to those who followed a low dairy foods weight loss plan.  Furthermore, the reduction in adipose cell size was the same between the low and adequate dairy groups and no changes were observed on markers of inflammation.

 

Selected Articles

 

1.    Barrack, M., Van Loan, M.D. 2011. Proper nutrition can prevent negative health outcomes in young female athletes. California Agriculture. 65:124. 

2.    Matvienko, O.A., Alekel, D.L., Bhupathiraju, S.N., Hoffman, H., Ritland, L.M., Reddy, M.B., Van Loan, M.D., Perry, C.D. 2011. Androidal fat dominates in predicting cardiometabolic risk in postmenopausal women. Cardiology Research and Practice. DOI: 10.4061/2011/904878. 

3.    Van Loan, M.D., Keim, N.L., Adams, S.H., Souza, E., Woodhouse, L.R., Thomas, A., Witbracht, M., Gertz, E.R., Piccolo, B., Bremer, A.A., Spurlock, M. 2011. Dairy foods in a moderate energy restricted diet do not enhance central fat, weight & intra-abdominal adipose tissue loss or reduce adipocyte size & inflammatory markers in overweight & obese adults; Controlled feeding study. Journal of Obesity. 2011: 989657. 

4.    Smilowitz, J.T., Wiest, M.M., Teegarden, D., Zemel, M.B., German, J.B., Van Loan, M.D. 2011. Dietary fat and not calcium supplementation or dairy product consumption is associated with changes in anthropometrics during a randomized, placebo-controlled energy-restriction trial. Nutrition and Metabolism. 8:67. 

5.    Shedd-Wise, K.M., Alekel, D.L., Hofmann, H., Hanson, K.B., Schiferl, D.J., Hanson, L.N., Van Loan, M.D. 2011. The soy isoflavones for reducing bone loss study: 3-yr effects on pQCT bone mineral density and strength measures in postmenopausal women. Journal of Clinical Densitometry. 14:47-57. 

6.    Barrack, M.T., Van Loan, M.D., Rauh, M.J., Nichols, J.F. 2011. Body mass, training, menses, and bone in adolescent runners: a 3-yr follow-up. Medicine and Science in Sports and Exercise. 43:959-66.

 

7.    Schaal, K., Van Loan, M.D., Casazza, G.A. 2011. Reduced catecholamine response to exercise in amenorrheic athletes. Medicine and Science in Sports and Exercise. 43:34-43. 

8.    Farr, J.N., Van Loan, M.D., Lohman, T.G., Going, S.B. 2011. Lower physical activity is associated with fat infiltration within skeletal muscle in young girls. Medicine and Science in Sports and Exercise. 43:443. 

9.    Bhupathiraju S.N., Alekel D.L., Stewart J.W., Hanson L.N., Shedd K.M., Reddy M.B., Hanson K.B., Van Loan M.D., Genschel U., Koehler K.J.  Relationship of circulating total homocysteine and C - reactive protein to trabecular bone in postmenopausal women.  J Clin Densitometry 10: 1-9. 2007. 

10.  Weaver C.M., McCabe L.D., McCabe G.P., Novotny R., Van Loan M., Going S., Matkovic V., Boushey C., Savaiano D.A.  Bone mineral and predictors of bone mass in White, Hispanic, and Asian early pubertal girls.  Calcified Tissue Int’l.  81: 352-363. 2007. 

11.  Matlik L., Savaiano D., McCabe G.,  Van Loan M., Blue C.L., Boushey C.J. Perceived milk intolerance is related to bone mineral content in 10-13 year-old adolescent females.  Pediatrics 120: e669-e677. 2007. 

12.  Shedd K.M.,  Hanson K.B., Alekel D.L., Schiferl D.J., Hanson L.N., Van Loan M.D. Quantifying leisure physical activity and its relation to bone density and strength.  Med Sci Sports Exerc. 39: 2189-2198. 2007. 

13.  Ritland L.M., Alekel D.L., Matvienko O.A., Hanson K.B., Stewart J.W., Hanson L.N., Reddy M.B.,  Van Loan. M.D., Genschel U. Centrally located body fat is related to appetitive hormones in healthy postmenopausal women. Eur J Endocr. 158: 889–897. 2008. 

14.  Teegarden D, White K.M., Lyle R.M., Zemel M.B., Van Loan M.D., Matkovic V., Craig B.A., Schoeller D.A.  Calcium and dairy product modulation of lipid utilization and energy expenditure.  Obesity 16: 1566-1572. 2008. 

15.  Perry C.D., Alekel D.L., Ritland L.M., Bhupathiraju S.N., Stewart J.W., Hanson L.N., Matvienko O.A., Kohut M.L., Reddy M.B., Van Loan M.D., Genschel U.  Centrally located body fat is related to inflammatory markers in healthy postmenopausal women.  Menopause 15: 619-627. 2008. 

16.  Stewart J.W., Alekel D.L., Ritland L.M., Van Loan M., Gertz E., Genschel U.  Serum 25-hydroxyvitamin D is related to indicators of overall physical fitness in healthy postmenopausal women.  Menopause 16: 1093-1101, 2009. 

17.  Alekel D. L.,Van Loan M.D., Koehler K.J., Hanson L.N., Stewart J.W., Hanson K.B., Kurzer M.S., Peterson C.T.,  Soy Isoflavones for Reducing Bone Loss (SIRBL) Study:  Three year randomized controlled trial to determine efficacy and safety of soy isoflavones in reducing bone loss in postmenopausal women. Am J Clin Nutr. 91: 218-230, 2010. 

18.  Matvienko O.A., Alekel D.L., Genschel U., Ritland L., Van Loan M.D., Koehler K.J. Appetitive hormones, but not isoflavone tablets, influence overall and central adiposity in healthy postmenopausal women. Menopause 17: 594-601, 2010. 

19.  Gertz ER, Silverman NE, Wise KS. Hanson KB, Alekel DL Stewart JW, Perry CD, Bhupathiraju SN, Kohut ML, Van Loan, MD. Contribution of serum inflammatory markers to changes in bone mineral content and density in postmenopausal women: A 1-yr investigation. J Clin Densitometry Assessment of Skeletal Health 13: 277-288, 2010. 

20.  Barrack M.T., Nichols J., Rauch M., Van Loan M. Physiological and behavioral indicators of an energy deficiency among female adolescent runners with elevated bone turnover.  Am J Clin Nutr 92: 1-8, 2010.  

21.  Shedd-Wise K.M., Alekel D.L., Hofmann H., Hanson K.B., Schiferl D.J., Hanson L.N., Van Loan M.D. The soy isoflavones for reducing bone loss study: 3-yr effects on pQCT bone mineral density and strength measures in postmenopausal women. J Clin Densito: Assess Skelet Health, 2011.  DOI: 10.1016/j.jocd.2010.11.003. 

22.  Barrack, M.T., Van Loan M.D., Rauch M.J., Nichols J.J. Body mass, training, menses, and bone in adolescent runners: A 3 year follow-up study.  Med Sci in Sports & Exerc. 2011: 43: 959-966. DOI: 10.1249/MSS.0b013e318201d7bb. 

23.  Matvienko O.A., Alekel, D.L.,  Bhupathiraju, S.N.,  Hofmann, H., Ritland, L.M., Reddy, M.B. , Van Loan, M.D., Perry, C.D. Androidal fat dominates in predicting cardiometabolic risk in postmenopausalwomen. Cardiol Res and Prac. 2011, Article ID 904878, doi:10.4061/2011/904878. 

24.  Witbracht M.G., Laugero K.D., Van Loan M.D., Adams S.H., Keim N.L. Performance on the Iowa Gambling Task is related to magnitude of weight loss and salivary cortisol in a diet-induced weight loss intervention in overweight women.  Accepted: J Physiol Behav. April 2011. 

25.  Van Loan M.D., Keim N.L., Adams S.A., Souza E., Woodhouse L.R., Thomas A., Witbracht M., Gertz E.R., Piccolo B., Bremer A.A., Spurlock M.  Dairy foods in a moderate energy restricted diet do not enhance central fat, weight, and intra-abdominal adipose tissue losses nor reduce adipocyte size or inflammatory markers in overweight and obese adults: A controlled feeding study. J. Obesity  Volume 2011 (2011), Article ID 989657

 

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Last Modified: 10/30/2014