|I am surprised at the number of nutritionists, medical doctors and even some governmental officials who do not know or want to acknowledge that mineral depletion of our soils has lessened food value. This has prompted me to publish important portions of a report and study done by two prominent English Doctors and Food Scientists, R.A. McCance and E.M. Widdowson. This is a study on the mineral depletion of the foods available to the United Kingdom over a period from 1940 to 1991. The data used as a basis of this study was published in five editions, initially under the aesthesis of the Medical Research Counsel (1940, 2, 3, 4) and later, the Ministry of Agriculture, Fishery and Foods (5, 6) and the Royal Society of Chemistry.
Part of the analysis includes the mineral content in milligrams per 100 gram portions of that food. The analysis provided information on the amounts of Calcium, Magnesium, Potassium, Phosphorous, Iron, Copper and Sodium. It was found that only certain foods within the categories of Vegetables, Fruits and cuts of Meat could be readily traced over this 51-year period. The result of comparing data available in 1940 with that in 1991 demonstrates that in every sub group of foods investigated, there has been a substantial loss in their mineral content.
Background; In 1926, Dr. R.A. McCance undertook, with a grant from the Medical Research Council, to analyze raw and cooked fruits and vegetables for their total 'available carbohydrates'. So began a program of analysis which resulted, in 1940, with the publication of the Medical Research Council's, Special Report No: 235 entitled "The Chemical Composition of Foods". This report represented the culmination of a comprehensive research program on the chemical composition of foods available to the British public. 100 grams of different Vegetables, Fruits, Cereals, Meats, Seafood's, Beverages, Beers, Sugars, Preserves, Sweetmeats, Condiments, and Dairy Products were analyzed for their organic and mineral content as well as portions of traditional British food recipes including Cakes, Pastries and Puddings.
This, then, was the first determined effort by a number of dedicated Doctors and Food Scientists headed by McCance and Widdowson to establish definitives by which to quantitatively compare and contrast individual dietary intakes. This 1st Edition was subsequently updated by the Medical Research Council in 1946 and 1960 as new foods became available, analytical procedures improved and new information regarding constituents of food (e.g. vitamins/amino acids, etc.) were considered as being needed. Over the next 30 years, the need to continually update information resulted in the 4th and 5th Editions, which were published in 1978 and 1991, respectively under the title of 'The Composition of Foods', this time under the auspices of the Ministry of Agriculture Fisheries and Food in conjunction with the Royal Society of Chemistry.
On comparing and contrasting the 1940 figures with the 1991 figures, quite a number of variables exist; enough in some instances such as cereals, to make comparisons meaningless. Equally, there is a wealth of data variable, which provides very real insights to the change in food values over the 51 years between 1940 and 1991. The 1940 data often incorporates work published in 1929, 1933 and 1936; similarly the 5th Edition published in 1991 contains data that originates in 1987.
The Food Analysis; In the first Edition, the foods were analyzed for water content, total nitrogen, protein, fat, available carbohydrates, mineral content and acid base balance. In the context of this report, only the mineral analysis was of interest and considered. The minerals assayed for were Sodium (Na), Potassium (K), Magnesium (Mg), Calcium (Ca), Phosphorous (P), Iron (Fe), Copper (Cu), Nitrogen (N) and Chlorine (C1). The amounts were recorded in milligrams per 100 grams of the food. Details such as a description of the food, where it was sourced, how many samples were used, its preparation (who/with peel/top leaves, etc) and its condition, raw or cooked (and if so, how and for how long), was often recorded for each item of food. In this way, like could be compared to like with regards to the variety of food and the cooking time. With foods where both raw and cooked values were given, the raw value was the one selected.
In later Editions, information on the dietary fiber, energy values and the vitamin content of foods was incorporated; the nitrogen content was dropped and a more complete break down of the amino acid composition was given. Zinc analysis was conducted in the 1978 Edition and Selenium, Iodine and Manganese in the 1991 Edition. Obviously, the analytical procedures changed for the years between 1940 and 1991. However, to quote the Forward of the 5th Edition "Those methods (of 40 years ago) were no less accurate than the modern automated ones, but they took a much longer time".
Presentation of information; The Vegetables selected represent those that were described by the authors as being of the same variety e.g. runner beans (raw) in 1940 with runner beans (raw) in 1991. Many of the vegetables on original lists were not subsequently analyzed i.e. artichokes, butter beans, celeriac, endive, etc. While others such as peppers, yam, plantain, okra, garlic, fennel, etc. were only analyzed in later years.
Of the original 28 raw vegetables and 44 cooked vegetables detailed in the 1st Edition, 27 vegetables (together with mushroom) could be traced through the 5th Edition. In order to make the summary of results easier to read, these vegetables were grouped in order of their dominant characteristic i.e.: bulb, root, etc and the results presented in Table 1. The individual values are presented in Appendix 3. In addition to the individual percentage change in the minerals Na, K, Mg, Ca, P, Fe and Cu, the change in the ratios between Ca:P, Na:K, Mg:Ca and Fe:Cu were also calculated. Where the vegetable has been boiled, it is usually in distilled water, normally with no salt. It is interesting to note the change between 1940 and 1991, in what was considered an appropriate time to cook a vegetable i.e. for broccoli in 1991, it was 15 minutes, and in 1940 it was 45 minutes! When comparing the results of the analysis, it is pertinent to bear this in mind.
In the 1960 and 1976 Editions, Zinc was assayed for the first time: where this value has been given, it has been included in the table at the appropriate date. Also, within the 3rd and 4th Editions, certain 'new' vegetables were analyzed.
Fruits - In a similar manner to the vegetables, 17 fruits were 'followed through' from the 1940 to 1991 Editions and changes in their individual mineral content recorded and presented in a summary sheet.
Meats - With regards to comparing Meat, Poultry and Game (1940) with Meat and Meat products (1991), there were, surprisingly, only 10 items that were readily comparable. This situation was created, to quote from Edition 5, "The conformation of farm animals had altered and methods of butchering had changed since the 1930's".
Discussion of results; Vegetables - With most vegetables, when they are harvested, it is usually the whole plant that is taken. An exception would be the 'Pod and Seeds' and 'Fruit' groups where there is the possibility of the rest of the plant being plowed back into the soil. Consequently, vegetables are probably the best indicators of change relating to the mineral depletion of soils. If the soils become depleted in minerals, the minerals are simply not there to become incorporated within the plant structure, which ultimately affects the plant's 'health' and consequently, the farmer's profitability when harvesting the crop.
Obviously, this situation has been known to farmers since the land was first cultivated and hence the tradition in primitive cultures to move on after 10 years growing at one site, or to regularly replenish the nutrients with fertilizers, or to leave the fields to 'fallow'. It was discovered early in the 1900's that Nitrogen, Phosphorous and Potassium were the main minerals required for plant growth. These minerals, together with adequate water, light and carbon dioxide seemingly allowed for optimum growth. Consequently, since the 1920's, NPK fertilizers have been routinely added to agricultural soils in the UK. Calcium, in the form of lime and Iron are also sometimes added to fertilizers.
The base figures used in the tables presented must, there fore, not be considered as a 'true, unadulterated' representation of the mineral content of any specific vegetable. In this regard, it is interesting to note that in their introduction to the vegetable section of the 5th Edition, the author's state, "Any differences arising from the method of cultivation, for example 'organic' methods appear to be small and inconsistent". Also, in the introduction of the 5th Edition, page 1, the authors acknowledge, "the nutritional value of many of the more traditional foods has changed. This can happen when there are new varieties of sources of supply for the raw materials with new farming practices which can affect the nutritional value of both man and animal products". Despite these remarks however, the summary provides evidence of an alarming change over 51 years. This data illustrates that there has been a severe depletion in the mineral content of the vegetables available.
During this time, there has been an average:
Loss of 49 percent of their Sodium content
Loss of 16 percent of their Potassium content
Loss of 24 percent of their Magnesium content
Loss of 46 percent of their Calcium content
Loss of 27 percent of their Iron content
and a massive 76 percent loss of their Copper content
Perhaps not too surprisingly, given the regular use of NPK fertilizer, the only exception is Phosphorous, which shows a 9% rise. These losses include the analytical results of vegetables, which were boiled at least twice as long in 1940 as in 1991 with the probable ensuing greater loss of mineral content. The individual analysis tables provide insights as to the ranges of highs and lows within these figures. The greatest individual mineral losses (mg per 100 gm sample)
Sodium - Runner Beans 6.5 to trace (nearly 100% loss)
Potassium - Spinach (boiled) 490 to 230 (less 53%) Potatoes 568 to 360 (less 36%)
Phosphorous - Spinach (boiled) 93 to 28 (less 70%)
Potatoes 0.15 t 0.8 (less 47%)
Magnesium - Carrots 12 to 3 (less 75%)
Calcium - Broccoli (boiled) 160 to 40 (less 75%)
Spring Onion 125 to 35 (less 74%)
Iron - Spinach (boiled) 4 to 1.6 (less 60%)
Swede 0.35 to 0.1 (less 71%)
Copper - Spinach (boiled) 0.26 to 0.01 (less 96%) Watercress 0.14 to 0.01 (less 93%)
Perhaps two of the most concerning results relate to two regularly used vegetables in the British diet, 'Old' Potatoes and 'Old' Carrots. During the 51 year period, carrots lost 75% of their Magnesium, 48% of their Calcium, 46% of their Iron and 75% of their Copper, while the traditional 'spud' lost 30 percent of its Magnesium, 35 percent of its Calcium, 45 percent of its Iron and 47 percent of its Copper. You would have needed to eat 10 tomatoes in 1991 to have obtained the same copper intake as one tomato would have given you in 1940.
In addition to the overall mineral depletion changes recorded, there has also taken place significant changes in the ratios of minerals to one another. Given that there are known critical ratios of certain minerals within our physiology (Ca:P, Na:K, Mg:Ca, Fe:Cu), the changes in these ratios were calculated for each individual vegetable. An overall summary is given below:
||1 : 2
||1 : 1
||1 : 10
||1 : 17
||1 : 4.8
||1 : 3.4
||1 : 10
||1 : 30
The figures, therefore, represent a significant change in the ratios between the minerals, which in turn could well have a significant influence on our health through the body's biochemistry.
Vegetables (1978-1991), Unfortunately, only 7 vegetables could be traced over this 13 year period. The results are again disconcerting; during this time there has been an average:
Loss of 39 percent of their Sodium content
Loss of 16 percent of their Potassium content
Loss of 14 percent of their Phosphorous content
Loss of 33 percent of their Magnesium content
Loss of 40 percent of their Calcium content
Increase 6 percent of their Iron content
Loss of 72 percent of their Copper content
Loss of 59 percent of their Zinc content
Fruit, The analytical results of 17 fruits traced through from
1940 to 1991, a summary is given below:
Loss of 29 percent of their Sodium
Loss of 19 percent of their Potassium
Loss of 2 percent of their Phosphorous
Loss of 16 percent of their Magnesium
Loss of 16 percent of their Calcium
Loss of 24 percent of their Iron
Loss of 20 percent of their Copper
Loss of 27 percent of their Zinc
Unlike a vegetable, when a fruit is harvested, the whole plant is not taken. Consequently, the changes evident are not so startling. Nevertheless, there are significant overall losses in mineral content. Also, when individual fruits are considered, you would have needed to eat 3 apples or oranges in 1991 to supply the same Iron content as 1 apple in 1940. It is also pertinent to note that the 10 fruits assayed for Zinc in 1978 show an overall 27% loss in their 1991 values. Blackcurrants, Olives and Tangerines have the same values in 1991 as given in 1940.
Meats, 10 items of meat could be compared. It is interesting to note that some analysis given in the 5th Edition are exactly the same as given in the 1st, these include Pork Loin (grilled), Rabbit, Veal Filet, Venison (roasted), Tripe (dressed), Sheep's Tongue, Ox Tongue, Grouse, Goose, Partridge, Pheasant and Pigeon. A summary of the mineral losses is given below; there has been an average:
Loss of 30 percent of their Sodium
Loss of 16 percent of their Potassium
Loss of 28 percent of their Phosphorous
Loss of 10 percent of their Magnesium
Loss of 41 percent of their Calcium
Loss of 54 percent of their Iron
Loss of 24 percent of their Copper
Again, there is a significant loss in all minerals assayed for, which could reflect the fact that these animals are fed on produce that itself is minerally depleted! The alarming 41% loss in Calcium could be a spurious reading due to the difficulty of extracting all bone from the flesh in the original analysis but the 54% loss of Iron cannot be so readily explained. Copper in meats and meat products were not routinely assayed for in 1940 hence, the lack of data.