Applied nutritional investigationNo association between fruits or vegetables and non-alcoholic fatty liver disease in middle-aged men and women
Introduction
Non-alcoholic fatty liver disease (NAFLD) is characterized by fat accumulation in the liver not caused by excess alcohol intake. NAFLD is a common liver disease both in Western [1], [2] and Asian countries [3] and can proceed to more severe liver diseases such as liver cirrhosis or hepatocellular carcinoma [4]. Thus, it is important to clarify the lifestyle factors that relate to NAFLD. Although the pathogenesis of NAFLD has not been fully revealed, it is strongly associated with increased peripheral fatty acid flux in the insulin-resistant state and also with de novo lipogenesis [5].
It is well known that fruit and vegetable intake is inversely associated with several insulin resistance-related diseases. This has naturally led to the hypothesis that fruit and vegetable intake also is associated with a low prevalence of NAFLD. Fruits and vegetables supply potentially protective dietary factors, such as antioxidant vitamins, for NAFLD [6]. In fact, the Mediterranean diet, which is rich in antioxidants from fruits and vegetables, is considered a potential dietary regimen for NAFLD prevention, although studies regarding its efficacy are limited cross-sectional studies and intervention studies in high-risk populations [7]. On the contrary, one study showed that fruit intake was positively associated with NAFLD prevalence in Chinese women [8]. Another study in Korea showed that vegetable intake, but not fruit intake, was inversely associated with NAFLD prevalence, and the authors speculated that the lack of an inverse relation of fruits to NAFLD might be due to fructose [9]. These findings are partly supported by studies using dietary pattern analysis: NAFLD prevalence was positively associated with a “fruits” pattern [10] and inversely with a “grain and vegetables” pattern [11].
Despite the failure of epidemiologic studies to demonstrate an association of fructose with NAFLD pathogenesis independently of excess energy intake [12], fructose still has received attention as a potential risk factor for NAFLD, mainly based on biochemical knowledge [13], [14]. Some consumers might not accurately understand recommendations for regulating added sugar intake or distinguish food sources of added versus naturally occurring sugar [15]. Indeed, even patients with diabetes educated by health professionals incorrectly believe that they need to avoid foods containing any sugar [16]. Thus, misunderstanding the relationship between health and sugar is considered common and might interfere with the global health campaign recommending fruit and vegetable consumption [17]. Additional studies examining the relationship between the intake of fruits and vegetables with NAFLD may help develop dietary strategies to prevent NAFLD. To our knowledge, such studies are few and none have been conducted in a Japanese population.
In the present study, we assessed the relationship between the consumption of fruits and vegetables and the prevalence of NAFLD in middle-aged men and women. Considering that each subtype of vegetable might be differently associated with insulin resistance [18], we also assessed the relationship by vegetable subtype.
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Study setting and participant selection
The participants in this cross-sectional study were recruited at the Center for Preventive Medicine at St. Luke's International Hospital in Tokyo, Japan. All individuals who planned to undergo a health examination during the investigation period (from January to April 2015) received a brief-type self-administered diet questionnaire (BDHQ) and a document informing them of the objectives of the study. Of the eligible participants (4758 men and 5112 women), 3163 men and 3662 women consented to
Results
Mean (SD) fruit intake was 48.8 (40.6) g/1000 kcal in men and 67.2 (47.5) g/1000 kcal in women. Mean (SD) total vegetable intake was 136.6 (69.8) g/1000 kcal in men and 182.1 (89.4) g/1000 kcal in women. Fruits contributed to 21.7% of total vitamin C intake in men and 25% in women. Vegetables were a more important dietary source of vitamin C (41.9% in men and 44.3% in women) than fruits. A substantial part of dietary fiber was derived from vegetables (41% in men and 46.5% in women), as well as
Discussion
In this study, fruit and total vegetable intakes were not inversely associated with NAFLD prevalence. In women, a linear inverse association between green and yellow vegetables was observed in the obesity-adjusted model, but ORs for any upper intake quartiles were not significant.
Mainly based on animal studies, fructose is considered to be one of the most important dietary factors in the pathogenesis of NAFLD [13], [14]. In Chinese women, NAFLD prevalence was positively associated with a
Conclusions
Results from the present study demonstrated that no relationship exists between fruit and vegetable intake and NAFLD prevalence in middle-aged Japanese men and women. These populations do not need to restrict fructose intake from fruits to prevent NAFLD. Moreover, we found no evidence to recommend a higher intake of certain types of vegetable to prevent NAFLD. Further studies are needed to detail the association between the intake of fruits and NAFLD prevalence, particularly using dietary
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Fructose impairs fat oxidation: Implications for the mechanism of western diet-induced NAFLD
2023, Journal of Nutritional BiochemistryCitation Excerpt :Others have also shown that fructose consumption on a normal diet (e.g., 13% calories from fat) does not induce weight gain [42], suggesting that a higher percent of fat in a diet is required to observe the obesogenic properties of fructose. This hypothesis is in line with the well-established fact that fructose intake from fruits and vegetables, as a part of well-balanced diet, does not lead to obesity and metabolic complications [43,44]. On the other hand, we showed that 30% fructose supplementation of mice on a HFD worsens weight gain and metabolic dysfunction as compared to 30% glucose supplementation [41].
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2021, Nutrition, Metabolism and Cardiovascular DiseasesCitation Excerpt :The study found that green and yellow vegetables were inversely associated with NAFLD only in women (OR = 0.49, 95% CI: 0.29–0.85). Consistent with our results, the inverse association between green and yellow vegetables and NAFLD was significantly attenuated after further adjusting for BMI (OR = 0.54, 95% CI: 0.27–1.07) [32]. However, their study was hampered by relatively small sample size (n = 2444) and not adjusted for overall dietary patterns.
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2020, Nutrition ResearchCitation Excerpt :Robert Lustig confirmed that short-term isoenergetic fructose restriction decreased liver fat [45], suggesting that excessive sugar consumption may cause NAFLD. However, the association between fructose contained in fruits and NAFLD has not been consistently shown [46]. Further cohort studies and randomized trials are needed to explore this association.
This work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI grant nos. 14 J11939 and 23240104. JSPS had no role in the design, analysis or writing of this article.