Francisco Grande

DENSITOMETRIC ANALYSIS OF BODY COMPOSITION: REVISION OF SOME QUANTITATIVE ASSUMPTIONS*

One can trace to Archimedes the idea that in a system consisting of two additive components which are mixed but the densities of which are known ( d l , d 2 ) , the determination of the density of the system ( D ) allows one to calculate the proportional masses of the two components. Let’s denote these components as W1 and W2.S Then, in a system with total weight W = W1 + Wz, the general equation for calculating component W1 expressed as a fraction (w1) of the total body weight is:

Serum cholesterol response to changes in the diet: IV. Particular saturated fatty acids in the diet.

For many dietary changes satisfactory prediction of the average change in the serum cholesterol level of man in mg./100 ml., is given by Δ Chol. = 1.35(2ΔS − ΔP) + 1.5ΔZ where S and P are percentages of total calories provided by glycerides of saturated and polyunsaturated fatty acids in the diet and Z2 = mg. of dietary cholesterol/1000 Cal. This formula fails, however, when the dietary change involves large amounts of cocoa butter and discrepancies also appear with beef tallow or hydrogenated coconut oil diets. Controlled dietary experiments at the University of Minnesota and at 2 other centers, provide 63 sets of comparisons of serum cholesterol averages for groups of men on each of 2 chemically characterized diets. Least-squares analysis indicates that stearic acid, as well as saturated fatty acids containing fewer than 12 carbon atoms, have little or no effect on serum cholesterol in man. The equation, Δ Chol. = 1.2(2ΔS′ − ΔP) + 1.5ΔZ, yields good correlation (r = 0.93) with the observed values in these 63 sets of data. This formulation also resolves heretofore puzzling discrepancies in the literature.

Serum cholesterol response to changes in the diet: II. The effect of cholesterol in the diet.

The series of metabolic ward experiments, with 22 physically healthy men in each, covered dietary cholesterol intakes from 50 to 1450 mg. daily, with all other variables controlled. The serum-cholesterol data, plus the data from comparable experiments reported from 4 other institutions, were analyzed in regard to average serum cholesterol response (Δ Chol., mg./100 ml.) to changed cholesterol intake. Least-squares solution, using serum cholesterol responses in 19 sets of dietary cholesterol comparisons, gives Δ Chol. = 1.5(Z2 − Z1), where the subscripts refer to the diets compared and Z is the square-root of the dietary cholesterol, measured as mg./1000 Cal. The correlation between the average Δ Chol. predicted and that observed is r = 0.95. The serum response was the same over a wide range of dietary fat composition. Ordinary American diets range from about about 150 to 350 mg. cholesterol/1000 Cal. These extremes correspond to an average difference of about 9 mg. of cholesterol/100 ml. of serum if all other variables are constant. Change from 250 mg./l000 Cal. to a cholesterol-free diet will cause an average fall of about 24 mg./100 ml. of serum. But a 50 per cent decrease in dietary cholesterol will produce an average decrease in the serum of only about 7 mg./100 ml. For the purpose of controlling the serum level, dietary cholesterol should not be completely ignored but attention to this factor alone accomplishes little.

Serum cholesterol response to changes in the diet: I. Iodine value of dietary fat versus 2S-P.

In men in calorie equilibrium, changes in dietary fat produce responses in the serum cholesterol level that, on the average, are predictable from the percentages of total calories provided by saturated (S) and polyunsaturated (P) fatty acid glycerides in the diets concerned. S and P have opposing actions and, in general, Δ Cholesterol (mg./100 ml.) = 2.7ΔS − 1.3ΔP, where Δ refers to the difference between 2 diets. Increasing the number of double bonds beyond 2 in polyunsaturated fatty acids does not result in proportionate increases in serum cholesterol-lowering effect. The mono-enes oleic and erucic acid have little or no effect on the serum cholesterol level when they are exchanged in the diet for equal calories of simple carbohydrate. Changes of fats in the diet produce serum cholesterol responses that are also correlated with the iodine values, or the square-roots of those values, of the fats concerned when the iodine value happens to be highly correlated with 2.7S - 1.3P. When changes in diet fats involve substantial differences in amounts of mono-enes, or of fatty acids containing more than 2 double bonds, the serum cholesterol response has a low or negligible correlation with the iodine value, or its square-root, of the fats.

Basal metabolism and age of adult man

Abstract Basal metabolism measurements made on young men were repeated after 19 yr. Basal metabolism was repeatedly measured over a period of 22 yr on men initially aged 44–56 yr. In the younger men the basal metabolic rate per individual man decreased by an average of only 3% in 19 yr but during this period these men had an average gain of 10.6 kg so there was a decrease of 9% in the average metabolic rate per unit of body weight. In the older men, average weight gain over 22 yr was only 1 kg, and there was not any significant decrease in individual oxygen consumption with age. The commonly cited figures on age changes in basal metabolism in adults, derived from cross-sectional surveys, much overestimate the true age effect.

Fiber and Pectin in the Diet and Serum Cholesterol Concentration in Man.

Summary Rigidly controlled experiments on middle-aged men subsisting on diets of natural foods with and without supplements of 15 g daily of either cellulose(fiber) or pectin failed to show any significant effect on serum cholesterol concentration from the cellulose but they did consistently show an effect from the pectin. The pectin effect was apparent in 3 weeks and amounted to an average fall of about 5% below the level on the same diet without pectin supplement. It is suggested that the amounts of cellulose and pectin used correspond to the upper levels of these substances provided in natural human diets.

Effect of intra-arterial insulin on tissue cholesterol and fatty acids in alloxan-diabetic dogs.

Insulin and saline were injected into the right and left femoral arteries respectively of 19 alloxan-diabetes-mellitus dogs for 1 to 28 weeks. A significant increase of artery tissue cholesterol and total fatty acids was found on comparing the insulin-administered right leg with the saline-administered left leg. Similarly, a significant increase of total fatty acids in muscle was found on comparing the right with the left leg of the alloxan-diabetes mellitus dogs. No significant differences were observed in the normal animals when the insulin-injected side was compared with the noninjected.

Serum cholesterol response to changes in the diet: III. Differences among individuals

Data from 227 men in 10 sets of controlled dietary experiments in 5 institutions gave the least-squares solution: [see text] with S.E. of slope --±0.44, where X is the serum cholesterol level of an individual, X is the average for all men on the same diet, and Δ is the response to a given dietary change. Equations, a chart and a table are provided for the prediction of the serum cholesterol response when change is made from one diet to another when cholesterol and fatty acid compositions of the diets are known. Comparison of predicted with observed average values in recently published data on samples of free-living people changing diets on prescription designed to lower serum cholesterol gave, predicted versus observed Δ: −30.0 vs. −28.5 and −27.2 vs. -30.1 mg./l00 ml. in men and women in caloric balance. In a sample of men who were also losing weight on a low-fat, low-cholesterol diet a change of −33.5 was predicted versus −39.8 observed.The series of metabolic ward experiments, with 22 physically healthy men in each, covered dietary cholesterol intakes from 50 to 1450 mg. daily, with all other variables controlled. The serum-cholesterol data, plus the data from comparable experiments reported from 4 other institutions, were analyzed in regard to average serum cholesterol response (Δ Chol., mg./100 ml.) to changed cholesterol intake. Least-squares solution, using serum cholesterol responses in 19 sets of dietary cholesterol comparisons, gives Δ Chol. = 1.5(Z2 − Z1), where the subscripts refer to the diets compared and Z is the square-root of the dietary cholesterol, measured as mg./1000 Cal. The correlation between the average Δ Chol. predicted and that observed is r = 0.95. The serum response was the same over a wide range of dietary fat composition. Ordinary American diets range from about about 150 to 350 mg. cholesterol/1000 Cal. These extremes correspond to an average difference of about 9 mg. of cholesterol/100 ml. of serum if all other variables are constant. Change from 250 mg./l000 Cal. to a cholesterol-free diet will cause an average fall of about 24 mg./100 ml. of serum. But a 50 per cent decrease in dietary cholesterol will produce an average decrease in the serum of only about 7 mg./100 ml. For the purpose of controlling the serum level, dietary cholesterol should not be completely ignored but attention to this factor alone accomplishes little.

Serum cholesterol in man: diet fat and intrinsic responsiveness.

Data obtained from a number of dietary experiments in man yield a formula by which the responses in serum cholesterol to changes in diet can be predicted. In this paper the reliability of this formula is tested and the effects of various types of fatty acids on serum cholesterol are investigated.

Role of Dietary Fat in Human Nutrition: III. Diet and the Epidemiology of Coronary Heart Disease

Coronary heart disease is the end result of the interplay of several, perhaps many, factors and no single cause will explain the developments that lead to the final clinical picture. Serious ischemia of the myocardium and of the conduction system of the heart, which is the basic functional fault, can be produced by coronary atherosclerosis or thrombosis or, most commonly, by a combination of these obstructive processes. Atherosclerosis and thrombosis,