[Illustration: FIG. 7. GROWTH RATE OF YEAST UNDER ALFALFA EXTRACT
STIMULATION
This chart shows the effect of varying concentrations of an alfalfa extract on the growth rate of the yeast cell. The rate of growth was determined after the Funk method by centrifuging the cells after seventy- two hours incubation and measuring the volume in cubic centimeters. The shape of the curve shows that this method will not give comparative results unless the extracts tested are dilute enough for the determinations to fall in the steep part of the curve.]
Another reason for our attention to this test is that if it can be made to show vitamine effect it provides an excellent medium for investigation of vitamine "B" reactions, and a method for studying the effect of the vitamine upon the protoplasm of a single cell.
CHAPTER V
THE SOURCES OF THE VITAMINE
Having now considered the general principles involved in vitamine testing we may justly ask what information they have yielded us in regard to the distribution of the vitamines in nature. If we must include vitamines in our diets it is important to know how to select foods on this basis, hence a classification of them on the ground of vitamine distribution becomes essential. The newness of the subject and the limited tests that have been made as well as the uncertainty residing in the test results make any classifications presented more or less approximations but we present such attempts as have been made, with the understanding that these tabulations are merely guides and not quantitative measurements in the sense that tables giving calorie values of protein, fat and carbohydrate content are. The following table (1) has been freely copied from a report of the British Medical Research Committee to which acknowledgment is hereby given.
TABLE 1
Pages 50 and 61 of the British Medical Research Committee's report
__________________________________________________________________________
| | |
CLASSES OF FOODSTUFFS |VITAMINE "A"|VITAMINE "B"|VITAMINE "C"
___________________________________|____________|____________|____________
| | |
Fats and oils: | | |
Butter . . . . . . . . . . . . | +++ | 0 |
Cream . . . . . . . . . . . . . | ++ | 0 |
Cod-liver oil . . . . . . . . . | +++ | 0 |
Mutton and beef fat or suet . . | ++ | |
Lard . . . . . . . . . . . . . | 0 | |
Olive oil . . . . . . . . . . . | 0 | |
Cotton seed oil . . . . . . . . | 0 | |
Cocoanut oil . . . . . . . . . | 0 | |
Cocoa-butter . . . . . . . . . | 0 | |
Linseed oil . . . . . . . . . . | 0 | |
Fish oil, whale oil, herring | | |
oil, etc. . . . . . . . . . . | ++ | |
Hardened fats (hydrogenated) | | |
of animal or vegetable origin | 0 | |
Margarine from animal fat . . . | In propor- | |
| tion to | |
| animal | |
| fat used | |
Margarine from vegetable fat | | |
or lard . . . . . . . . . . . | 0 | |
Nut butters . . . . . . . . . . | + | |
Meat, fish, etc.: | | |
Lean meat (beef, mutton, etc.) | + | + | +
Liver . . . . . . . . . . . . . | ++ | ++ | +
Kidneys . . . . . . . . . . . . | ++ | + |
Heart . . . . . . . . . . . . . | ++ | + |
Brain . . . . . . . . . . . . . | + | ++ |
Sweetbreads . . . . . . . . . . | + | ++ |
Fish, white . . . . . . . . . . | 0 | Very slight|
| | if any |
Fish fat (salmon, herring, etc.)| ++ | Very slight|
| | if any |
Fish roe . . . . . . . . . . . | + | ++ |
Tinned meats . . . . . . . . . | ? | Very slight| 0
Milk, cheese, etc.: | | |
Milk, cow's whole raw . . . . . | ++ | + | +
Milk, cow's skim . . . . . . . | 0 | + | +
Milk, cow's dried whole . . . . | Less than | + | Less than
| ++ | | +
Milk, cow's boiled whole . . . | ? | + | Less than
| | | +
Milk, cow's condensed sweetened | + | + |
Cheese, whole milk . . . . . . | + | | Less than
| | | +
Cheese, skim milk . . . . . . . | 0 | |
Eggs, fresh . . . . . . . . . . | ++ | +++ | 0?
Eggs, dried . . . . . . . . . . | ++ | +++ | 0?
Cereals, pulses, etc.: | | |
Wheat, maize, rice (whole germ) | + | + | 0
Wheat, maize, rice germ . . . . | ++ | +++ | 0
Wheat, maize, rice bran . . . . | 0 | ++ | 0
White wheat flour, pure corn | | |
flour, polished rice, etc. . | 0 | 0 | 0
Custard powders, egg substi- | | |
tutes prepared from cereal | | |
products . . . . . . . . . . | 0 | 0 | 0
Linseed, millet . . . . . . . . | ++ | ++ | 0
Dried peas, lentils, etc. . . . | | ++ |
Pea-flour, kilned . . . . . . . | | 0 | 0
Soy beans, haricot beans . . . | + | ++ | 0
Germinated pulses or cereals . | + | ++ | ++
Vegetables and fruits: | | |
Cabbage, fresh, raw . . . . . . | ++ | + | +++
Cabbage, fresh, cooked . . . . | | + | +
Cabbage, dried . . . . . . . . | + | + |Very slight
Cabbage, canned . . . . . . . . | | |Very slight
Swedes, raw expressed juice . . | | | +++
Lettuce . . . . . . . . . . . . | ++ | + |
Spinach, dried . . . . . . . . | ++ | + |
Carrots, fresh, raw . . . . . . | + | + | +
Carrots, dried . . . . . . . . |Very slight | | Less than
| | | +
Beetroot, raw, expressed juice | + | + |
Potatoes, raw . . . . . . . . . | | | +
Potatoes, cooked . . . . . . . | | | ++
Beans, fresh scarlet runners raw| | |
Lemon juice, fresh . . . . . . | | | +++
Lemon juice, preserved . . . . | | |
Lime juice, fresh . . . . . . . | | | ++
Lime juice, preserved . . . . . | | |Very slight
Orange juice, fresh . . . . . . | | | +++
Raspberries . . . . . . . . . . | | | ++
Apples . . . . . . . . . . . . | | | +
Bananas . . . . . . . . . . . . | + | + |Very slight
Tomatoes, canned . . . . . . . | | | ++
Nuts . . . . . . . . . . . . . | + | ++ |
Miscellaneous: | | |
Yeast dried . . . . . . . . . . | ? | +++ |
Yeast extract and autolysed . . | ? | +++ | 0
Meat extract . . . . . . . . . | 0 | 0 | 0
Malt extract . . . . . . . . . | | + in some |
| | specimens |
Beer . . . . . . . . . . . . . | | 0 | 0
Honey . . . . . . . . . . . . . | | + |
___________________________________|____________|____________|____________
+++ indicates abundant; ++ relatively large; + present in small amount; 0 absent.
The following table (2) has been compiled from a review of both British and American data and represents a rather more complete classification than the British report. The four plus system has also been used to permit more complete comparisons.