Mineral depletion in foods

over the period 1940 to 1991

by David Thomas M.Sc, D.I.C

 

 

Many people in the UK are malnourished despite the fact that, in terms of quantity of food eaten, the vast majority have one of the best diets in the world. It is my opinion that a prevalent causative factor in the aetiology of illness in general is lack of appropriate nutrition. Why .should this be?

Most nutritionists suggest that it is the quality of our present day foods that is lacking when compared to those same foods in the past. Vital nutrients are missing - frequently these are trace minerals known to have a beneficial effect on our health. This situation creates a stress within our metabolism as our bodies strive to maintain the homeostatic balance that allows us to adjust to our ever-changing environment.

I was enthused to undertake the study from which this article is extracted, by a 1999 UK lecture tour by American Herbalist, Paul Bergner, author of the book 'The Healing Power of Minerals'1 in which he published research conducted on the depletion of minerals in American diets. I decided that, so that British people may become aware of the conclusions of his research, I would conduct a similar study to ascertain if any such data existed on the mineral depletion, over time, of foods available to the British public.

 

The tables that follow are a selection from my full report hut the results are worrying and, I believe, justify daily mineral supplementation. The source of the information used to compile my report is the McVance and Widdowson data published by the Medical Research Council (1940)1,4.5 and M.A.F.F.6,7 These books provide statistics on the chemical composition of foods available to us as a nation between the period 1940 to 1991. Part of the analysis includes the mineral content in mg per 100gm portion of that food. Only certain foods in the categories of vegetables fruits and cuts of meats could readily be traced over the 51 year period, but when data available in 1940 was compared with that in 1991, it was found that in every sub-group of food investigated there has been a substantial loss in mineral content.

 

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 available that provides very real insights to the changes in food values over the 51 vears between 1940 and 1991.

 

Lack of space precludes inclusion of all the data tabulated in my report,2 but Table I shows the general trends. For more information contact the author though the journal.

 

Vegetables

The vegetables selected represent those described by the authors as being of the same variety e.g. runner beans (raw) in 1940 compared with runner beans (raw) in 1991. Many of the vegetables on original lists were not subsequently analysed (i.e. artichokes, butter beans, celeriac, endive). Whilst others (such as peppers, yam, plantain, okra, garlic, fennel) were only analysed in later years. Of the original 28 raw and 44 cooked vegetables detailed in the 1st edition. 27 vegetables (together with mushrooms) could be traced through to the 5th edition.

Vegetables are probably the best indicators of change relating to the mineral depletion of soils. If soils become depleted in minerals, the minerals are simply not there to become incorporated within the plant structure.

It was discovered early in the 1900s that nitrogen, phosphorous and potassium were the main minerals required for plant growth and together with adequate light, water and carbon dioxide, seemingly allowed for optimum growth. Consequently since the 1920s, NPK fertilisers have been routinely added to agricultural soils in the UK. Readers will note that the only mineral showing an increase is phosphorous, with a 9% rise.

 

It is also interesting to note the change between 1940 and 1991 in what was considered an appropriate time to cook a vegetable; for broccoli in 1991 it was 15 minutes, in 1940 it was 45 minutes! When comparing the results of the analysis it is pertinent to bear this in mind as the losses shown include the analytical results of vegetables boiled at least twice as long in 1940 compared to 1991, with the probable ensuing greater loss of mineral content.

 

Fruits

In a similar manner to the vegetables, 27 fruits were followed through from 1940 to 1991 and changes in their individual mineral content recorded and presented. Unlike a vegetable, when a fruit is harvested the whole plant is not taken. Consequently the changes are not so large. Nevertheless there are significant overall losses in mineral content. When individual fruits are considered, you would have needed to eat three apples or oranges in 1991 to supply the same iron content as in 1940. Dr Paul Clayton has pointed out to me that the fall in copper in plants, although apparently significant, may be due to the reduced use of copper sulphate sprays, so these data on their own vould be an unsatisfactory proxy for the other trace elements. To follow up on this I have spoken to the Henry Double Day Association, regarding the historical use of Copper Sulphate Sprays but I have yet to receive a reply.

 

 

Table 1:

Summary of changes in the mineral content of some foods between 1940 and 1991

Year of analysis

Mineral

Vegetables

(27 varieties)

Fruit

(17 varieties)

Meat

(10 cuts)

Milk

Cheddar Cheese

1940 1991

Sodium (Na)

Less 49%

Less 29%

Less 30%

Plus 10%

Not available

1940 1991

Potassium (K)

Less 16%

Less 19%

Less 16%

Less 12.5%

Less 34%

1940 1991

Phosphorous (P)

Plus 9%

Plus 2%

Less 28%

Less 3%

Less 10%

1940 1991

Magnesium (Mg)

Less 24%

Less 16%

Less 10%

Less 21%

Less 47%

1940 1991

Calcium (Ca)

Less 46%

Less 16%

Less 41%

Less 4%

Less 11%

1940 1991

Iron (Fe)

Less 27%

Less 24%

Less 54%

Less 38%

Less 47%

1940 1991

Copper (Cu)

Less 76%

Less 20%

Less 24%

Trace only

Same

These statistics have been compiled by comparing and contrasting data first published in 1940 by McCance and Widdowson - 'Chemical Composition of Food', commissioned by the Medical Research Council - with that data by the same authors in 1991 - commissioned by the Royal Society of Chemistry and the Ministry of Agriculture Fisheries and Food.

 

 

 

Meats

With regards to comparing meat, poultry and game in 1940 with the 1991 figures, surprisingly only ten items were readily comparable due to changes in style of butchering. However, the game food data has not changed, as they are the same as used in the 1940 edition The significant losses found could reflect the fact that these animals are fed on produce that is itself minerally depleted - including one another. The alarming 41% loss of calcium could be a spurious reading due to the difficulty of extracting all bone from flesh in the original analysis, but the 54% loss of iron cannot be so readily explained and one might question the data. If all the meats tested (including game meats such as partridge, pheasant and pigeon and rabbit) had really lost over half their iron content over such a brief period of time, surely there would be evidence of wide-spread malaise (anaemia, immune-suppression) in both wild and farmed animals? It is interesting to check whether this data is supported elsewhere. In his book1 (page 65) Paul Bergner cites US Department of Agriculture figures between 1963 and 1992 that show a 36% loss of iron in ground beef and 21% in chicken. These are less alarming than the apparent 54% loss shown by the McCance and Widdowson data, but still show a large fall over the 29 year period.

 

Dairy

Again it is hard to compare like with like in dairy data because of the homogenisation, pasteurisation and changes in types of milk products that occurred during the intervening 51 years. Consequently the only reasonable comparisons are milk (fresh/whole) and Cheddar cheese. As an example of the underlying data, the individual mineral figures for milk and Cheddar cheese are included as Tables 2 and 3.

 

Table 2: Milk

Mineral

1940 mg/100g

1991 mg/100g

Change

Sodium

50

55

Plus 10%

Potassium

160

140

Less 12.5%

Phosphorous

95

92

Less 3%

Magnesium

14

11

Less 21%

Calcium

120

115

Less 4%

Iron

0.08

0.05

Less 38%

Copper

0.02

Trace

 

 

 

 

Table 3: Cheddar Cheese

Mineral

1940 mg/100g

1991 mg/100g

Change

Sodium

 

 

 

Potassium

116

77

Less 34%

Phosphorous

545

490

Less 10%

Magnesium

46.9

25

Less 47%

Calcium

810

720

Less 11%

Iron

0.57

0.3

Less 47%

Copper

0.03

0.03

Same

 

 

Discussion

It could be said that it doesn't matter much if levels of sodium, calcium, magnesium, phosphorus and iron have fallen in vegetables and fruit, because plant foods are not very important sources of these minerals anyway. However, there are now three million vegetarians in the UK who would wish consideration regarding the mineral content derived from plant sources.

Levels in meat and dairy are important and here, milk analysis shows less than 4% drop in calcium, for example, which is probably insignificant. The shifts in magnesium (down 21% in milk) appear to be significant, but are hard to square with the calcium data. Iron in milk is unimportant.

Trace elements are somewhat different and should be taken very seriously, because there is reasonable evidence that many people are depleted in these, and that this is a contributing factor to ill health.

It is a limitation of my report that there are no P values presented for any of the shifts and I wish I had the time to compile more rigorous statistics. If anyone would be interested in analysing this data further, please contact me through the journal.

 

 

 

Conclusion

On comparing all the lisis of foods in the 1st and 5th editions it can be seen that the dietary habits of people in the UK have changed dramatically. There has been a rise in the popularity of refined, processed foods, often high in saturated fats, sugars, colourings, preservatives and flavourings. Herbicides, fungicides, pesticides, antibiotics and hormones may have contaminated the raw materials from which these foods have been manufactured. In addition, as this report has demonstrated, there has also been a significant deterioration in the mineral content of those foods - vegetables, fruit and meat - often considered the foundation of a 'good diet'. Is it really being radical to question whether there is a link between these changes and the rise in chronic disease conditions?

 

 

References:

1    Bergner Paul. (1997). The Healing Power of Minerals, Prima Health 0-7615-1021-4

2   Thomas D (1/2000) A study on the mineral depletion of the foods available to us as a nation over the period 1940 to 1941.

3    McCance and Widdowson (1940) 1st Edition, "The Chemical Composition of Foods" published by Medical Research Council: Special Report Series No: 235

4   McCance and Widdowson (1946) 2nd Edition, "The Chemical Composition of Foods" published by Medical Research Council: Special Report Series No: 235

5    McCance and Widdowson (1960) 3rd Edition, "The Chemical Composition of Foods" published by Medical Research Council: Special Report Series No: 297

6   McCance and Widdowson (1976) 4th Edition, "The Chemical Composition of Foods" published by RSC/MAFF

7   McCance and Widdowson (1991) 5th Edition. "The Chemical Composition of Foods" published by Medical Research Council: Special Report Series No: 235

 

David Thomas graduated in Geology and later gained an M.Sc. in Mineral Exploration. He worked for nine years in copper, cobalt, lead, zinc, gold and uranium exploration and mining and is a Fellow of the Geological Society. Subsequently he retrained in America in the field of Chiropractic and later in Nutrition, being a Founder Member of the Register of Nutritional Therapists.