gastric emptying and fat

The physical state and the spatial distribution of fat within the gastric lumen during digestion are critical factors influencing the rate of fat delivery to the small intestine. This will affect the rate of fat absorption and metabolism and the signalling between the gut and brain. Fat digestion commences in the mouth with the secretion of acid lipase from salivary glands, which is particularly important in infants and those with pancreatic insufficiency.
Acid lipase from the salivary gland and from the gastric fundus act within the stomach causing approximately 10% of dietary triacyl glycerides to be hydrolysed to fatty acids. Together with gastric phospholipid and dietary emulsifiers, these fatty acids facilitate the formation of emulsions with particle size 1-10 μm suitable for the action of pancreatic lipases.
Intragastric lipolysis is an important determinant of gastric emptying.
The intracellular fat component of a test meal empties with the solid phase of a meal, whilst a liquid fat component that is free from the solid phase of the meal empties much more slowly than the aqueous phase of the meal.
Marciani et al in previous studies have shown that acid-stable emulsions stimulate greater cholecystokinin release and are associated with delayed gastric emptying, compared with acid-unstable emulsions. The mechanism for these differences is uncertain. Stable emulsions, which do not break under acid conditions, present a larger surface area for lipolysis, which may cause greater concentrations of fatty acids to reach the duodenum, where they can exert their satiating effect both by acting on fat-sensitive enteroendocrine cells, and by delivering lipid-laden chylomicrons into the venous and lymphatic systems.
Acid-unstable emulsions in which the fat layer empties after the aqueous phase, deliver fat with a markedly reduced interface area. Since the lipolysis takes place almost exclusively at the fat-aqueous interface, lipolysis products are likely to be created more slowly in the duodenum and upper small bowel.
Marciani et al have shown that it is possible to delay gastric emptying and increase satiety by stabilising the intragastric distribution of fat emulsions against the gastric acid environment.
This raises fascinating possibilities for cooking.
Marciani et al 2009 Effect of intragastric acid stability of fat emulsions on gastric emptying, plasma lipid profile and post prandial satiety. British J Nurtion vol 101 pp 919-928

body composition and skin fold measurements.

This is an important paper relating to central topic in nutrition, body composition equations.
Generalised skinfold equations developed in the 1970s are commonly used to estimate laboratory-measured percentage fat (BF%). The equations were developed on predominately white individuals using Siri's two-component percentage fat equation (BF%-GEN). Jackson and colleagues have cross-validated the Jackson-Pollock (JP) generalised equations with samples of young white, Hispanic and African-American men and women using dual-energy X-ray absorptiometry (DXA) as the BF% referent criterion (BF%-DXA). The cross-sectional sample included 1129 women and men (aged 17 -35 years). The correlations between BF%-GEN and BF%-DXA were 0·85 for women and 0·93 for men.
Analysis of measurement error showed that BF%-GE underestimated BF%-DXA of men and women by 1·3 and 3·0%.
General linear models (GLM) confirmed that BF%-GEN systematically underestimated BF%-DXA of Hispanic men and women, and overestimated BF%-DXA of African-American men.
These results showed that BF%-GEN and BF%-DXA were highly correlated, but the generalised equations lacked accuracy when applied to these racially and ethnically diverse men and women.
The inaccuracy was linked to the body composition and race/ethnic differences between these Training Intervention and Genetics of Exercise Response (TIGER) study subjects and the men and women used to develop the generalised equations in the 1970s and using BF%-DXA as the referent criterion.
Jackson et l 2009 Cross-validation of generalised body composition equations with diverse young men and women : the training intervention and genetics of exercises response (TIGER ) study British Journal Nutrition vol 101 871-878A

Resting energy expenditure and fat mass

Inter-individual variance in resting energy expenditure (REE) is important in interpreting (i.e. normalizing) or even predicting metabolic rate. Fat-free mass (FFM) explains 70-80 % of variance in REE. FFM is regarded as the metabolically active, oxygen-consuming body cell mass. By contrast, fat mass (FM) is the metabolically inert lipid compartment of the body. FM (in kg) is however a dependent contributor to the variance in REE, due to the energy requirement of adipose tissue. The specific metabolic rate of lean tissue ranges from 54 kJ/kg for skeletal muscle to 1841 kJ/kg for heart and kidney, whereas the specific metabolic rate of adipose tissue is low 1l·3-14·3kJlkg lipid.
In contrast, regression equations from population analyses give different relationships between the effect of either FFM or FM on REE, i.e. the ratio between the regression coefficients of FFM and FM on REE ranged between 1·5: 1 and 7: 1, suggesting that each kg of lean tissue exerts a 1·5 - 7 times greater effect on REE than did each kg of fat tissue. These discrepancies may result from by differences in age between study populations or the amount of fat tissues which might affect the secretion of metabolically active adipose tissue-derived hormones such as leptin, resitine or adiponectin.
This study by Bosy-Westphal et al provides a systematic analysis of the relationship between REE, FFM,
They used a database of 1306 women and a linear regression model, and analysed the contribution of FM to the total variance in REE at different grades of adiposity (ranges of body %FM). After adjusting for age, the relative contribution of FM on REE variance increased from low (>10 %FM) to normal (> 10 to 30 %FM) and moderately elevated (> 3cto 40 %FM) grades of adiposity but decreased sharply at high (>40 to 5O %FM) and very high (> 5O %FM) grades of adiposity according to the ratio between regression coefficients. These data suggest that the specific metabolic rate of fat tissue is reduced at high adiposity.
Resting energy expenditure: Fat mass: Fat-free mass: Women

Bosy-Westphal et al 2009 grade of adiposity affects the impact of fat mass on resting energy expenditure in women Brit J Nutrition vol 101 pp 474-477

osteoporosis and vitamin D status

An adequate vitamin D status is of major importance for bone health. And is dependent on adequate vitamin D intake and sun exposure. Fish is the only natural important dietary sources of vitamin D. Milk, some milk products and cereals are supplemented to different degrees depending on the country, with a much higher degree of fortification in the USA. On the other hand, season, latitude and time of the day, clothing and sunscreen, pigmentation of the skin and ageing are the main factors contributing to the cutaneous production of vitamin.
Vitamin D inadequacy is a common worldwide, more particularly in Europe. In Middle-Eastern countries, Lebanon, Saudi Arabia, Kuwait and Jordan .several recent studies have shown a surprisingly high incidence of vitamin D deficiency in young individuals and schoolchildren.
Despite an adequate vitamin D intake being considered an essential component of osteoporosis management the prevalence of vitamin D inadequacy in osteoporotic women is very high; vitamin D inadequacy affects 64 % of osteoporotic women worldwide
In the paper Gannage-Yared and colleagues analysed vitamin D-inadequacy risk factors among the 251 Lebanese postmenopausal osteoporotic women (from both Muslim and Christian communities). Vitamin D inadequacy prevalence (25-hydroxyvitamin D (25(OH)D) < 30nglm1) was 84·9%. 25(OH)D was negatively correlated with BMI and positively correlated with educational level and self-reported general health but not with age and no seasonal variation was observed. There was no significant correlation between 25(OH)D and sun exposure index or vitamin D-rich food consumption. However, 25(OH)D strongly correlated with vitamin D supplement intake. Muslim community participants had lower 25(OH)D levels compared with their Christian counterparts. They also had higher BMI, lower educational level and vitamin D supplement consumption and followed more frequently a dress code covering the arms. In a multivariate model, in Muslims, inadequate vitamin D supplements and a dress code covering the arms are the independent predictors of 25(OH)D inadequacy .However, in Christians, the predictors are inadequate vitamin D supplements, high BMI and low educational level

Gannage-Yared et al 2009 Prevalence and predictors of vitamin D inadequacy
amongst Lebanese osteoporotic women Brit J Nutrition vol 101 487-491

neonatal vitamin A supplementation

Vitamin A supplementation in children aged 1-4 is an important intervention for improving health and mortality rates in developing countries. Improvements of 20-30% have been observed.
Gogia and Sachdev have looked at the value of supplementation in reports on babies aged less than 1 month. There was no benefit from such intervention
Gogia and Sachdev 2009 Neonatal vitamin A supplementation of mortality and morbidity in infancy: systematic review of randomised controlled trials . BMJ vol 338 pp 871-875

medium chain acylcoenzyme A dehydrogenase deficiency

Newborn screening in England and Northem Ireland includes screening for medium chain acylcoenzyme A dehydrogenase (MCAD) deficiency within the entire newborn population. M CAD deficiency is the most common inherited disorder of mitochondrial fatty acid oxidation in people from northern Europe. This autosomal recessive metabolic disease affects about one in 10000 people in the United Kingdom. Homozygosity for this mutation has not been found in black or Asian ethnic groups that have been screened in England, which suggests that MCAD deficiency caused by the 985A>G mutation is a disease of white ethnic origin.
Individuals with undiagnosed MCAD deficiency typically present clinically with failure of fatty acid oxidation after fasting and an inability to generate energy during periods of increased energy demand. With symptomatic hypoglycaemia through hepatic encephalopathy (similar to that seen in Reye's syndrome) to sudden unexpected infant death, which may be classified as sudden infant death syndrome. Most cases present before 2 years of age (mean age 13 months), although a variable spectrum of disease is increasingly recognised, with both neonatal and adult presentation being reported
About a third of affected individuals will remain asymptomatic throughout life but may be at risk of metabolic decompensation in periods of critical energy supply-for example, during infection or prolonged fasting.
About 25% of patients with undiagnosed MCAD deficiency die at or shortly after the first presentation." A further large group of undiagnosed patients presents too late to prevent long term neurological disability. However, if the diagnosis is made early, children with this deficiency can expect to lead a full and normal life, with simple dietary treatment aimed mainly at the avoidance of fasting.
Since the first descriptions of MCAD deficiency in the early 1980s, laboratory methods for diagnosis have improved greatly. During the past decade, measurement of newborn bloodspot concentrations of octanoylcarnitine by tandem mass spectrometry has emerged as a primary screen for MCAD deficiency that has high sensitivity and specificity. Multiple analytes are now possible , phenylalanine, the screening marker for phenylketonuria, can be measured at the same time as octanoylcarnitine.
Newborn screening for MCAD deficiency is now used in many countries.
To date, in the UK more than 1.5 million newborn babies have been screened using the heelprick sample collected at 5-8 days of age and measuring octanoylcarnitine as a single biomarker. Predictive value is high-194 babies screened positive, and 152 (78%) were confirmed to have MCAD deficiency .
Editorial BMJ Screening for MCAD deficiency in newborns BMJ vol 338 p 843
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light diet and obstetric labour

A strength of the double blind trial in clinical work is to challenge old postures in care and give clear and safe guidelines.
Such a trial was to determine whether or not a light diet affects women’s ability to deliver normally and safely. Every Maternity suite throughout the world has its own policy.
Such a trial is recorded in the BMJ 11th April 2009. Consumption of a light diet
( described as a low fat, low residue diet eaten at will ) and the control was water.
The women were nulliparous as the labour was likely to be longer.
Both groups had the same outcome so it is reasonable to allow a light diet during labour. The danger is of aspiration and this is most likely in the obese .
O’Sullivan et al 2009 Effect of food intake during labour on obstetric outcome: randomised controlled trial BMJ vol 338 p 880
Editorial BMJ 2009 Eating a light diet during labour BMJ vol 338 p 842.

Hot tea and cancer of the oesophagus

Tea has been promoted as a health engendering drink, and no doubt it is. However a very important paper from Iran and a supporting Editorial in the BMJ of 11th April 2009 indicate that tea drunk at temperatures over 75° C results in an enhanced risk of cancer of the oesophagus.
Mrs Beeton suggested, (did she ever suggest?) that a 5 to 10 minutes interval between making and pouring tea was important for flavoursome tea.
Another aphorism for tea bags is the first minute releases the colour wait for the taste.
And reduce the chance of cancer of the oesophagus.

Islami et al 2009 Tea drinking habits and oesophageal cancer in a high risk area in Northern Iran: population based case- control study. BMJ vol 338 pp 876-879
Editorial BMJ 2009 Hot tea and increased risk of oesophageal cancer. BMJ vol 339 pp 841-2

Carbon dioxide and plants

Trees and plants are growing faster and bigger in response to the large amounts of carbon dioxide being excreted into the atmosphere as a result of the carbon fuels being burnt. This increase is right across the range of plants, rain forests to British sugar beet. However this utilisation is only a fraction of the of CO2 released. The concentration of CO2 in the air has risen from 278 parts per million in 1750 to 380 ppm currently.
Each hectare of African forest is utilising an extra 0.6tonnes of carbon a year compared with 1960.
This means 5 tonnes of the 50 tonnes per year of carbon that is being passed into the atmosphere. This does not allow for destruction of rain forests
Jonathan Leake in Sunday Times . 5th April 2009, p 12

drugs and sport

Any one interested in sport and Sport’s nutrition will be aware of. The UK national anti-doping agency UK Sport has published its figures for the period 2004 to 2008 f the problem of drugs to enhance performance.
There are interesting sports e.g. snooker where doping is commoner than in many other sports.

Number of positive results for prohibited substances per 1,000 tests

Bodybuilding 57.5

Powerlifting 43.8

Basketball 31.2

Weightlifting 18.6

Snooker l7.7

Welsh rugby union 15.6

Rugby league 13.8

Boxing 7.9

Cycling 1.9

Athletics 1.1
FT weekend March 21/22 2009 page 14 written Tara Kelly

BMI and mortality

This is a major review of a very important topic and the mortality and morbidity associated with obesity. The main associations of body-mass index (BMI) with overall and cause-specific mortality can best be assessed by long-term prospective follow-up of large numbers of people. The Prospective Studies Collaboration examined these associations by sharing data from many studies.
Collaborative analyses were undertaken of baseline BMI versus mortality in 57 prospective studies with 894576 participants, mostly in western Europe and North America (61% [n=541452] male, mean recruitment age 46 [SD 11] years, median recruitment year 1979 [IQR 1975-85], mean BMI 25 [SD 4] kg/m2). The analyses were adjusted for age, sex, smoking status, and study. To limit reverse causality, the first 5 years of follow-up were excluded, leaving 66552 deaths of known cause during a mean of 8 (SD 6) further years of follow-up (mean age at death 67 [SD 10] years): 30416 vascular; 2070 diabetic, renal or hepatic; 22592 neoplastic; 3770 respiratory; 7704 other.
In both sexes, mortality was lowest at about 22·5-25 kg/m2. Above this range, positive associations were recorded for several specific causes and inverse associations for none, the absolute excess risks for higher BMI and smoking were roughly additive, and each 5 kg/m2 higher BMI was on average associated with about 30% higher overall mortality (hazard ratio per 5 kg/m2 [HR] 1·29 [95% Cl 1.27-1·32]): 40% for vascular mortality (HR 1·41 [1·37-1·45]); 60-120% for diabetic, renal, and hepatic mortality (HRs 2·16 [1·89-2.46], 1·59 [1·27-1·99], and 1· 82 [1. 59-2·09], respectively); 10% for neoplastic mortality (HR 1·10 [1· 06-1·15]); and 20% for respiratory and for all other mortality (HRs 1· 20 [1·07-1·34] and 1·20 [1·16-1·25], respectively). Below the range 22· 5-25 kg/m2, BMI was associated inversely with overall mortality, mainly because of strong inverse associations with respiratory disease and lung cancer. These inverse associations were much stronger for smokers than for non-smokers, despite cigarette consumption per smoker varying little with BM!.
Although other measures (eg, waist circumference, waist-to-hip ratio) could well add extra information to BMI, and BMI to them, BMI is in itself a strong predictor of overall mortality both above and below the apparent optimum of about 22·5-25 kg/m2. The progressive excess mortality above this range is due mainly to vascular disease and is probably largely causal. At 30-35 kg/m2, median survival is reduced by 2-4 years; at 40-45 k/jm2, it is reduced by 8-10 years (which is comparable with the effects of smoking). The definite excess mortality below 22·5 kg/m2 is due mainly to smoking-related diseases, and is not fully explained.
Prospective Studies Collaboration 2009 Body-mass index and cause-specific mortality in 900000 adults: collaborative analyses of 57 prospective studies Lancet vol 373 pp 1083-1096
And a eview
Lopez-Jiminez 2009 Speakable and unspeakable facts abut BMI and mortality Lancert vol 373 pp 1055 - 1056