Anin vivo¹³C magnetic resonance spectroscopic study of the relationship between diet and adipose tissue composition

Abstract

13C magnetic resonance spectroscopy (MRS) is a noninvasive technique used in the study of lipids. We applied 13C MRS to assess the effects of long-term dietary variation on adipose tissue composition in humans. In vivo 13C MRS was used to analyze the fatty acid composition of adipose tissue in 88 healthy volunteers with significantly different diets (38 vegans, 11 vegetarians, and 39 omnivores) assessed by analysis of dietary records. Results were compared with the serum lipid profile. 13C MRS revealed clear differences in the adipose tissue composition of vegans, which contained more unsaturated (P < 0.01) and fewer saturated fatty acids (P < 0.01) compared with omnivores and vegetarians. The vegan subjects had a significantly lower intake of saturated fatty acids and higher intake of polyunsaturated fatty acids than either the omnivore or the vegetarian groups (P < 0.01). These findings were associated with significantly lower levels of serum total cholesterol and low density lipoprotein-cholesterol in the vegan group compared with the omnivores. Our results demonstrate the use of 13C MRS for the noninvasive study of adipose tissue composition and its application to the study of the interaction between long-term dietary and metabolic risk factors in humans.

Body Fat MRS

“…Beckmann et al found that the level of unsaturation measured from the 13 C MR spectra of adipose tissue from volunteers following 6 months adherence to either a fat-reduced or high-fat diet agreed with that assessed from their subjects' dietary history 8 . Similarly Thomas et al reported clear differences between the adipose tissue composition of vegans, vegetarians and omnivores, which was strongly linked to the fatty acid composition of their habitual diet 9 . Interestingly, the high levels of polyunsaturated fatty acids observed in the adipose tissue of vegan subjects were negatively associated with both total and low density lipoproteins (LDL)-cholesterol, suggesting that 13 C MRS could indeed be used as a non-invasive measure of 'metabolic health' 9 .…”

“…Similarly Thomas et al reported clear differences between the adipose tissue composition of vegans, vegetarians and omnivores, which was strongly linked to the fatty acid composition of their habitual diet 9 . Interestingly, the high levels of polyunsaturated fatty acids observed in the adipose tissue of vegan subjects were negatively associated with both total and low density lipoproteins (LDL)-cholesterol, suggesting that 13 C MRS could indeed be used as a non-invasive measure of 'metabolic health' 9 . Similarly, Hwang et al reported significantly elevated levels of monounsaturated and polyunsaturated fatty acids from the 13 C MR spectra of the adipose tissue of subjects following diets supplemented with either fish oil or Lorenzo's oil (high in monounsaturated fatty acids) 10 .…”

“…To date the main application of in vivo 13 C-MRS has been to examine the longterm effects of diet on the composition of AT in rodents 5,6 and humans [7][8][9][10] . As early as 1983, Canioni et al showed that modulation of essential fatty acids in the diet of rats altered the 13 C-MR spectrum of adipose tissue 5 .…”

Assessing gene expression in vivo: magnetic resonance imaging and spectroscopy

“…Most in vivo 13 C MRS studies augment the MR signal by using 13 C labelled tracers to follow metabolic pathways in the body, 22 but good quality signals may be obtained from glycogen and adipose tissue without enrichment. 23,24 In vitro MRS Intact tissue biopsies, cell suspensions, body fluids and tissue extracts can be examined by using in vitro MR spectroscopic techniques at much higher magnetic field strengths than the clinical systems. In vitro spectra are better resolved than those obtained from whole body tissue at 1.5 T, not only because of the higher magnetic field strengths used (11.7 T), but also because metabolites are uniformly distributed in solution.…”

Changes in adipose tissue composition in malnourished patients before and after liver transplantation: A carbon-13 magnetic resonance spectroscopy and gas-liquid chromatography study

“…In the future, this may be Although several studies have examined fat loss in ciruseful in optimizing the dietary management of severely rhotic patients, 19- grated for data analysis. Total unsaturated and saturated fatty acids Twenty-two patients (10 men and 12 women; mean age, 44.4 { 2.7 were calculated, as previously described, [23][24][25] allowing for the direct years) with histologically proven cirrhosis of varying etiology and comparison with data obtained by GLC. Data are expressed as the functional severity were studied: 10 with PSC (5 men and 5 women);…”