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Biomedical subjects

D A Southgate

Publications and source records attributed to D A Southgate.

At least 19 recordsLinked to original sources
PubMed1979

The digestion of pectin in the human gut and its effect on calcium absorption and large bowel function.

1. The effect of dietary fibre digestion in the human gut on its ability to alter bowel habit and impair mineral absorption has been investigated using the technique of metablic balance. 2. Five healthy male students were studied for 9 weeks under controlled dietary conditions and during the last 6 weeks they took 36 g pectin/d. Bowel habit, transit through the gut, faecal fibre excretion, calcium balance and faecal composition were measured. 3. During the control period only 15% of the dietary fibre ingested was excreted in the stools and when pectin was added to the diet there was no increase in fibre excretion. Stool frequency and mean transit time were unchanged by pectin but stool wet weight increased by 33% and faecal excretion increased (%) for fatty acids 80, nitrogen 47, total dry matter 28 and bile acids 35. Ca balance remained unchanged. 4. It may be concluded from these results that dietary fibre is largely metabolized in the human gut and dietary pectin completely so. This could explain its lack of effect on bowel habit and Ca balance. Other changes in the faeces may be related to an increase in bacterial mass.

Adult↗
PubMed1979

The effects of a supplement of dietary fibre on faecal excretion by human subjects.

1. Four human subjects on strictly controlled diets were given a fibre supplement, 25 g Ispaghula husk (Isogel)/d, for 3 weeks. 2. Replicate diets and faeces were collected during two 5 d balance periods. The first period served as control for the second which occurred after the supplement had been fed for 2 weeks. 3. Diets and faeces were analysed for total solids, gross energy, total nitrogen, fat, available and unavailable carbohydrates. 4. Three of the four subjects showed a considerable increase in faecal bulk; total faecal weight was more than doubled in two subjects. In two subjects the increase was brought about mainly by extra fibre in the faeces accompanied by a higher proportion of faecal water whereas in one subject it was also an increased excretion of nutrients. One subject showed very little change in faecal bulk. 5. High values for the apparent digestibility of fibre were found during the control period; from 0.70 to 0.80. There was more variation during the experimental period when apparent digestibility of total fibre ranged from 0.47 to 0.82. Values arrived at for the minimum apparent digestibility of the fibre supplement were generally high; one subject appeared to digest Isogel completely. Isogel was degraded preferentially to the food-derived fibre; in particular, cellulose in the faeces was increased during the experimental period. 6. Only one subject showed distinct decreases in the apparent digestibility of energy, N and fat in the diet. The results do not therefore agree with the generally held view that increased fibre in the diet decreases the apparent digestibility of the other nutrients.

Adult↗
PubMed1978

Calcium binding by dietary fibre.

Dietary fibre from plants low in phytate bound calcium in proportion to its uronic-acid content. This binding by the non-cellulosic fraction of fibre will reduce the availability of calcium for small-intestinal absorption, but the colonic microbial digestion of uronic acids will liberate the calcium. Thus the ability to maintain calcium balance on high-fibre diets may depend on the adaptive capacity of the colon for calcium absorption.

Binding Sites↗
PubMed1978

Colonic response to dietary fibre from carrot, cabbage, apple, bran.

Approximately 20 g/day of concentrated dietary fibre from carrot, cabbage, apple, bran, and guar gum was added to the controlled basal diet of nineteen healthy volunteers. Faecal weight increased by 12% on bran, 69% on cabbage, 59% on carrot, 40% on apple, and 20% on guar gum. These changes in faecal weight were correlated with an increased intake of pentose-containing polysaccharides from the fibre. On the basal diet there were pronounced individual differences in faecal weight, and from these the response of subjects to the fibre preparations could be predicted. Addition of fibre shortened mean transit-time through the gut and significantly diluted an inert marker in the faeces. Diet-induced changes in colonic function may explain international differences in the prevalence of colonic disease, whilst personal variation in the response to dietary fibre may determine individual susceptibility to large-bowel disease within a community.

Adult↗
PubMed1978

Dietary fiber: analysis and food sources.

The sources of dietary fiber are reviewed and the chemistry of the various components discussed in relation to their possible physiological properties and their analytical measurement in foods and the diet as a whole. Complete fractionation of all the polysaccharide species would be a time-consuming exercise; nevertheless some characterization of dietary fiber seems essential to an understanding of any physiological role. The composition of the dietary fiber in a range of foodstuffs is presented, and the relative contributions of the major food groups to the intake of total dietary fiber is outlined.

Cellulose↗
PubMed1978

Free sugars in foods.

The values for the free sugars analysed in the samples collected for the fourth edition of McCance and Widdowson's 'The composition of foods' have been combined with values from the literature to provide some basic information on the distribution of free sugars in a range of foods.

Dairy Products↗
PubMed1977

The effects of two dietary fiber supplements on gastrointestinal transit, stool weight and frequency, and bacterial flora, and fecal bile acids in normal subjects.

The effect of dietary supplements of sugar-cane fiber (bagasse), on stool weight, solids, and water content were studied in normal ambulant volunteers over a 9-mo period; a second inpatient study was done with bran supplements. The addition on 10.5 g of bagasse containing 5.1 g of crude fiber to a normal diet containing 3.7 g of crude dietary fiber daily raised the mean fecal weight from 88.3 +/- 6.4 g to 139.7 +/- 10.2 g/day (p less than 0.005). There was also a significant rise in fecal solids and fecal water, although the percentage of water in the stools remained unchanged. Bagasse supplements accelerated gastrointestinal transit when measured by the carmine marker technique. Radiopaque "shapes" showed a trend toward more rapid transit with bagasse supplements. Daily supplements of 39 g of wheat bran or 10.5 g of bagasse increased the total daily excretion of fecal bacteria, but there were no changes in bacteria excreted per gram of feces. The composition of the bacterial flora showed no change. There was increased excretion of fecal acid sterols on the bagasse supplement, but this failed to occur with bran. No changes attributable to fiber supplements occurred in the plasma triglycerides or cholesterol. Future work may define specific dietary fiber supplements for different therapeutic purposes. One fiber may be used as a bulk expander in diverticular disease and another as a hypocholesteremic fiber.

Adult↗
PubMed1976

Dietary fibre.

Explore the source record for details and available documents.

Cellulose↗
PubMed1976

Metabolic responses to dietary supplements of bran.

During a metabolic ward study, the addition of dietary fiber in the form of wheat bran biscuits to the diet of five volunteer subjects resulted in an increase in the stool wet weight and fecal solids. The excretion of fecal solids was highly correlated with the intake of unavailable carbohydrates, and fecal losses of water were similarly correlated with fecal excretion of these constituents. The major component of the increase in fecal solids was due to the noncellulosic polysaccharide fraction of dietary fiber. There was an increased fecal excretion of nitrogen fat and energy by most subjects when the supplement was eaten. However, the increased loss of energy in the feces was only 40-80 kcal/day, and therefore a large supplemental intake of dietary fiber had only minor effects on energy metabolism. Supplemental fiber is thus unlikely to induce a useful loss of calories in the management of obesity. The addition of dietary fiber caused an increased excretion of most inorganic constituents, particularly sodium and phosphorus; increased excretion of iron and magnesium was also found in two subjects.

Aged↗