nutrition
Felix
Bronner,’
nutrient
requirements
Ph.D.
The concept and nature of nutrient requirements are a major topic in nutrition teaching. When the amount of time for teaching nutrition is severely limited, as typical for the basic science curriculum of medical and dental undergraduates, nutrient requirements and allowances become the principal topic. This is so because under-
pendently regulated. Hence the balance is a complicated and usually poorly understood function of turnover. Moreover, because nutrient intake induces a variety of enzymatic processes, balances will vary with prior nutrient history. A good example is the marked increase in stature of the Japanese that has occurred since World War II.
0 U,
I
zo 0
u:z
a.
w
Q
z
i 10
1 9
8
10
7
]JTi
6
5
10
KILOGRAMS FIG. mended Allowance
i-I
6
3
American
1
JournalofClinical
0
LOG10
MICROGRAMS
10
MILLIGRAMS
MICROGRAMS
1. Recommended daily dietary allowance, represented Dietary Allowances, 8th Rev. Ed., 1974. National is for a 70 kg male, 23 to 50 years of age.
The
2
10
GRAMS
standing the pathophysiobogicab aspects of nutrition requires grounding in the needs of the normal individual and in how these are modified by disease. Students need to know how a nutrient requirement has been or can be established experimentally. In other words, they must be taught the nature of the nutrient balance and that it is a rate that represents the difference between input and output rates. These in turn often are inde-
726
>ir#{236}i: Ti
4
on a logarithmic scale. Adapted Academy of Sciences, Washington,
from RecomD.C. 1974.
This means input and output rates of present-day Japanese adults are much higher than 30 years ago, though the net balance of the two populations is unchanged. The example also demonstrates that the genetic potential for body size of the Japanese does not differ markedly from that of Americans, ‘ Professor necticut Health
Nutrition
30:
MAY
of Oral Center,
1977,
Biology, The Farmington.
pp.
726-727.
University Conn.
of Con06032.
Printed
in U .S.A.
Downloaded from https://academic.oup.com/ajcn/article-abstract/30/5/726/4650138 by Univ of Calif - San Francisco user on 01 January 2019
An aid to teaching and allowances
education
TEACHING
NUTRIENT
REQUIREMENTS
-
. -
.
.
.
.
.
ALLOWANCES
727
of a typical food, say of 100 g of meat or cheese, and to compare the intake scale with the nutrient requirement scale. Another way is to compare scales for different ages or physiological states and to highlight, by color, important differences. Figure 1 can also be modified to indicate upper limits beyond which nutrients may cause illness. Figure 1 permits placing the history of nutrition in perspective. Early nutrition nesearch, through the 19th century, was concerned primarily with understanding macronutnients. In the first half of the 20th century micronutnients were discovered, whereas current work is concerned with identifying oligonutnents. Disease processes that alter intake or availability of required nutrients can then be discussed. For example, an intake of 10 j.g of vitamin D will be inadequate when there is a disturbance in the enzymatic transformation of vitamin D to its active metabolite , 1 ,25-dihydroxy-vitamin D This disturbance requires either a massive input of vitamin D, or, if possible, a supply of the missing metabolite in an amount equal to that formed in normal individuals ingesting 10 g of vitamin D daily. Finally, if students are furnished with syllabi, inclusion of such a figure can serve as a reminder of what has been taught in lecture and provide a visual reminder of the relationships of nutrient quantity and quality. .
a
Downloaded from https://academic.oup.com/ajcn/article-abstract/30/5/726/4650138 by Univ of Calif - San Francisco user on 01 January 2019
provided calcium and protein intakes are equalized. Once the principle of the nutrient balance has been discussed and the limitations of the functional indices of balance techniques iilustrated body size , weight gain , mentation , an active versus a sedentary life , etc it becomes necessary to give some understanding to the relative importance of the various nutrients and to illustrate the meaning of classifying nutrients into macro-, micr0-, and oligonutrients. To do this I have found it useful to arrange nutrients on a logarithmic scale, as shown in Figure 1 (A somewhat similar arrangement was proposed by Klevay (Am . J Clin Nutr 23: 1639, 1970) whose list of nutrients, however, differs from that used here.) Such a scale orders essential nutrients in a readily comprehensible fashion and allows for easy comparison of various nutrients. I classify macronutrients as those required in greater than gram amounts, micronutrients as required in greater than microgram amounts, and oligonutrients as required in less than microgram quantities Alternate classifications are of course possible. Figure 1 also permits relating quantity to quality of food, so that the student can devebop a rational appreciation of the circumstances in which he or she should become concerned with intakes. One way to do this is to plot on a similar scale the composition
AND
Felix
Bronner,’
nutrient
requirements
Ph.D.
The concept and nature of nutrient requirements are a major topic in nutrition teaching. When the amount of time for teaching nutrition is severely limited, as typical for the basic science curriculum of medical and dental undergraduates, nutrient requirements and allowances become the principal topic. This is so because under-
pendently regulated. Hence the balance is a complicated and usually poorly understood function of turnover. Moreover, because nutrient intake induces a variety of enzymatic processes, balances will vary with prior nutrient history. A good example is the marked increase in stature of the Japanese that has occurred since World War II.
0 U,
I
zo 0
u:z
a.
w
Q
z
i 10
1 9
8
10
7
]JTi
6
5
10
KILOGRAMS FIG. mended Allowance
i-I
6
3
American
1
JournalofClinical
0
LOG10
MICROGRAMS
10
MILLIGRAMS
MICROGRAMS
1. Recommended daily dietary allowance, represented Dietary Allowances, 8th Rev. Ed., 1974. National is for a 70 kg male, 23 to 50 years of age.
The
2
10
GRAMS
standing the pathophysiobogicab aspects of nutrition requires grounding in the needs of the normal individual and in how these are modified by disease. Students need to know how a nutrient requirement has been or can be established experimentally. In other words, they must be taught the nature of the nutrient balance and that it is a rate that represents the difference between input and output rates. These in turn often are inde-
726
>ir#{236}i: Ti
4
on a logarithmic scale. Adapted Academy of Sciences, Washington,
from RecomD.C. 1974.
This means input and output rates of present-day Japanese adults are much higher than 30 years ago, though the net balance of the two populations is unchanged. The example also demonstrates that the genetic potential for body size of the Japanese does not differ markedly from that of Americans, ‘ Professor necticut Health
Nutrition
30:
MAY
of Oral Center,
1977,
Biology, The Farmington.
pp.
726-727.
University Conn.
of Con06032.
Printed
in U .S.A.
Downloaded from https://academic.oup.com/ajcn/article-abstract/30/5/726/4650138 by Univ of Calif - San Francisco user on 01 January 2019
An aid to teaching and allowances
education
TEACHING
NUTRIENT
REQUIREMENTS
-
. -
.
.
.
.
.
ALLOWANCES
727
of a typical food, say of 100 g of meat or cheese, and to compare the intake scale with the nutrient requirement scale. Another way is to compare scales for different ages or physiological states and to highlight, by color, important differences. Figure 1 can also be modified to indicate upper limits beyond which nutrients may cause illness. Figure 1 permits placing the history of nutrition in perspective. Early nutrition nesearch, through the 19th century, was concerned primarily with understanding macronutnients. In the first half of the 20th century micronutnients were discovered, whereas current work is concerned with identifying oligonutnents. Disease processes that alter intake or availability of required nutrients can then be discussed. For example, an intake of 10 j.g of vitamin D will be inadequate when there is a disturbance in the enzymatic transformation of vitamin D to its active metabolite , 1 ,25-dihydroxy-vitamin D This disturbance requires either a massive input of vitamin D, or, if possible, a supply of the missing metabolite in an amount equal to that formed in normal individuals ingesting 10 g of vitamin D daily. Finally, if students are furnished with syllabi, inclusion of such a figure can serve as a reminder of what has been taught in lecture and provide a visual reminder of the relationships of nutrient quantity and quality. .
a
Downloaded from https://academic.oup.com/ajcn/article-abstract/30/5/726/4650138 by Univ of Calif - San Francisco user on 01 January 2019
provided calcium and protein intakes are equalized. Once the principle of the nutrient balance has been discussed and the limitations of the functional indices of balance techniques iilustrated body size , weight gain , mentation , an active versus a sedentary life , etc it becomes necessary to give some understanding to the relative importance of the various nutrients and to illustrate the meaning of classifying nutrients into macro-, micr0-, and oligonutrients. To do this I have found it useful to arrange nutrients on a logarithmic scale, as shown in Figure 1 (A somewhat similar arrangement was proposed by Klevay (Am . J Clin Nutr 23: 1639, 1970) whose list of nutrients, however, differs from that used here.) Such a scale orders essential nutrients in a readily comprehensible fashion and allows for easy comparison of various nutrients. I classify macronutrients as those required in greater than gram amounts, micronutrients as required in greater than microgram amounts, and oligonutrients as required in less than microgram quantities Alternate classifications are of course possible. Figure 1 also permits relating quantity to quality of food, so that the student can devebop a rational appreciation of the circumstances in which he or she should become concerned with intakes. One way to do this is to plot on a similar scale the composition
AND
