Consensus view on the role of dietary fat and obesity

Differential responses of hepatic endoplasmic reticulum stress and inflammation in diet-induced obese rats with high-fat diet rich in lard oil or soybean oil

Scopes

To investigate the effects of high-fat diet enriched with lard oil or soybean oil on liver endoplasmic reticulum (ER) stress and inflammation markers in diet-induced obese (DIO) rats and estimate the influence of following low-fat diet feeding.

Methods and Results

Male SD rats were fed with standard low-fat diet (LF, n = 10) and two isoenergentic high-fat diets enriched with lard (HL, n = 45) or soybean oil (HS, n = 45) respectively for 10 weeks. Then DIO rats from HL and HS were fed either high-fat diet continuously (HL/HL, HS/HS) or switched to low-fat diet (HL/LF, HS/LF) for another 8 weeks. Rats in control group were maintained with low-fat diet. Body fat, serum insulin level, HOMA-IR and ectopic lipid deposition in liver were increased in HL/HL and HS/HS compared to control, but increased to a greater extent in HL/HL compared to HS/HS. Markers of ER stress including PERK and CHOP protein expression and phosphorylation of eIF2α were significantly elevated in HL/HL group while phosphorylation of IRE1α and GRP78 protein expression were suppressed in both HL/HL and HS/HS. Besides, inflammatory signals (OPN, TLR2, TLR4 and TNF-α) expressions significantly increased in HL/HL compared to others. Switching to low-fat diet reduced liver fat deposition, HOMA-IR, mRNA expression of TLR4, TNF-α, PERK in both HL/LF and HS/LF, but only decreased protein expression of OPN, PERK and CHOP in HL/LF group. In addition, HL/LF and HS/LF exhibited decreased phosphorylation of eIF2α and increased phosphorylation of IRE1α and GRP78 protein expression when compared with HL/HL and HS/HS respectively.

Conclusions

Lard oil was more deleterious in insulin resistance and hepatic steatosis via promoting ER stress and inflammation responses in DIO rats, which may be attributed to the enrichment of saturated fatty acid. Low-fat diet was confirmed to be useful in recovering from impaired insulin sensitivity and liver fat deposition in this study.

Decision-Making Deficits and Overeating: A Risk Model for Obesity

OBJECTIVE

To demonstrate that human overeating is not just a passive response to salient environmental triggers and powerful physiological drives; it is also about making choices. The ventromedial prefrontal cortex has been strongly implicated in the neural circuitry necessary for making advantageous decisions when various options for action are available. Decision-making deficits have been found in patients with ventromedial prefrontal cortex lesions and in those with substance dependence--impairments that reflect an inability to advantageously assess future consequences. That is, they choose immediate rewards in the face of future long-term negative consequences.

RESEARCH METHODS AND PROCEDURES

We extended this research to the study of overeating and overweight, testing a regression model that predicted that poor decision making (as assessed by a validated computerized gambling task) and a tendency to overeat under stress would correlate with higher BMI in a group of healthy adult women (N = 41) representing a broad range of body weights.

RESULTS

We found statistically significant main effects for both independent variables in the predicted direction (p < 0.05; R2 = 0.35). Indeed, the decision-making impairments across the 100 trials of the computer task were greater in those with high BMI than in previous studies with drug addicts.

DISCUSSION

Findings suggested that cortical and subcortical processes, which regulate one's ability to inhibit short-term rewards when the long-term consequences are deleterious, may also influence eating behaviors in a culture dominated by so many, and such varied, sources of palatable and calorically dense sources of energy.

The role of meat fat in the human diet

Food fat plays an important role in the human diet. On the one hand, fats provide the body with energy, contribute to the absorption of fat-soluble vitamins, and act as structural elements of cell walls. On the other hand, a high fat intake is associated with obesity, type 2 diabetes, cancer, and coronary heart disease. Animal fats, which contain a high proportion of saturated fatty acids, are often the focus of attention when it comes to reducing the share of fat in the diet. The present overview of the literature describes the amount of total fat and the percentage of individual fatty acid groups in meat and meat products, documents the contribution of meat and meat products to fat intake, and investigates the connection between meat fat and various diseases. The information given is based mainly on data material from Switzerland; data from other countries have been included for comparison.

An economic evaluation of the expanded food and nutrition education program

OBJECTIVE

To evaluate the New York State Expanded Food and Nutrition Education Program using economic methodology.

DESIGN

Data were collected by nutrition educators in a pretest, posttest design with an epidemiological modeling approach to assess costs and estimate potential health benefits of the state program.

SETTING

Cooperative Extension, 35 counties.

PARTICIPANTS

5730 low-income participants.

INTERVENTION

Series of 6 or more food and nutrition lessons.

MAIN OUTCOME MEASURES

Cost (program and participant); health benefits in quality adjusted life years (QALYs); and monetized benefits: society's willingness to pay for QALYs, and benefits of avoiding or delaying health care costs and loss of productivity.

ANALYSIS

Cost-effectiveness estimated from behavior change and QALY weights. Cost-benefit ratios estimated from costs and monetized benefits. Sensitivity analyses provided ranges where lack of agreement exists around parameters' values.

RESULTS

Cost was $892/graduate. Cost-effectiveness was 245 QALYs saved, at $20863/QALY (sensitivity 42-935 QALYs, $5467-$130311 per QALY). Societal willingness to pay benefit-to-cost ratio was $9.58:$1.00 (sensitivity $1.44-$41.92:$1:00); narrow governmental benefit-to-cost ratio was $0.82:$1.00 (sensitivity $0.08-$4.33:$1:00).

CONCLUSIONS AND IMPLICATIONS

Outcome data indicate that food and nutrition behavior changes resulting from the Program are likely to improve future health and reduce health care costs. Cost-effectiveness is estimated to be as great as for many current health interventions.

Predictors and dietary consequences of frequent intake of high-sugar, low-nutrient foods in 1-year-old children participating in the ABIS study

Foods rich in sugar have been suggested to contribute to the increasing prevalence of obesity in children. The aim of this report is to investigate the dietary pattern in 1-year-old children who frequently receive foods rich in sugar but low in nutrients and to study associated demographic and parental factors. During 1977-9, 21,700 infants were invited to participate in this prospective, population-based, longitudinal cohort study. Screening questionnaires were completed for 16,070 infants after delivery. Follow-up questionnaires from 10,762 children at 1 year of age are included in the analysis. It was found that 24% of the children received sweets/pastries more often than one or two times per week. They had a higher intake of French fries, potato crisps and cream as well as a lower intake of fruit and vegetables. A frequent intake of sugar-rich, low-nutrient foods was significantly associated with several maternal factors (high intake of sweets/pastries during pregnancy, young age, mother living alone) as well as presence of older siblings. Maternal smoking during pregnancy and maternal overweight were of borderline significance. Parental education level was inversely associated with the frequency of intake of sweets/pastries in the child. Children who frequently receive sweets/pastries also have an otherwise unfavourable dietary pattern. Several parental and demographic factors were associated with this feeding pattern, especially high intake of sweets/pastries during pregnancy. Screening of pregnant women for risk predictors like consumption of sweets/pastries, young age and smoking could be possible ways of identifying children at future risk for low dietary quality.

Implications of dietary fat for nutrition and energy balance

Probably, the majority of the population in modern consumer societies believes that the negative effects of dietary fat far outweigh the beneficial ones. Dietary fat is therefore considered the cause for obesity, and fat from animal origins is usually regarded as unhealthy whereas fat from plants is thought to be healthy and safe for human nutrition. However, public opinion is not compatible with current knowledge. Animal fat does not have a priori a fatty acid composition that is detrimental to good health. And though dietary fat is generally highly digestible and can be efficiently retained in body tissues, it is not the primary cause of obesity. The deposition of absorbed fat in excess of the oxidized amount occurs only under the situation of a positive energy balance. The latter depends not on fat intake alone, but rather on the amounts of all nutrients ingested and on energy expenditure as the second component of energy balance. A recommendation for moderation of dietary fat intake is nonetheless desirable because it is easy to overeat fatty (and sweet) foods. In the end, well-balanced diets help achieve intake of all indispensable nutrients.