Our New Zealand Correspondent
Many of us would like to think that this is the case, but there are growing doubts that the prescription can be relied upon. In recent years we have been assailed by messages about unsafe food. Is it from a mad cow? Is it soaked in pesticide residues? Are the bean sprouts riddled with salmonella? These warning messages are clear, yet one of the most important problems with today's food goes largely unrecognised. There is good reason to believe that the quality of natural foods, like fruit and vegetables, has undergone a dramatic decline. In other words, the food we ate 30 years ago contained more nutrients than the same items do today.
Quasi government agencies worldwide have decided that they will tell us what is good and what is bad for us. They, and supportive dieticians, now tell us to eat so much of this and that, to maintain health and ward off disease. They have decided on a simple message that equates quantity with quality. Publicity campaigns advise us to eat a certain number of portions, of a wide variety of food items. Our diet advisors assume that their recommendations will provide us with all our body's needs, thus eliminating the ridiculous practice of taking supplements to provide 'extra' nutrients. Interestingly, horticulturalists and farmers involved in animal husbandry have always been acutely aware of the importance of the quality of nutrition. They know that optimum nutrition is essential for their produce and they also know that the quality of the soil and other environmental factors are key to that. Can the best choice of food guarantee us optimum nutrition?
I have decided to examine the problem by trying to answer a few simple questions so that readers can decide for themselves.
Is there any evidence that today's food is less nutritious than that eaten by people 30, 50 or even 100 years ago?
In recent years a growing number of reports have appeared which concluded that some of today's foods are not as nutritious as those eaten in the past. A report in the Journal of Complimentary Medicine in 2001 pointed out that US and UK Government statistics show a decline in trace minerals of up to 76% in fruit and vegetables over the period 1940 to 1991. (1)
In 2003 News Canada reported that today's fruit and vegetables contain far fewer nutrients than they did 50 years ago. They claimed that potatoes, tomatoes, bananas and apples were notably less nutritious. For example, the study (source unidentified) found that potatoes had lost 100 % of their vitamin A content, 57% of their vitamin C and iron, and 28% of their calcium. The report went on to examine data from the US Department of Agriculture involving vegetable quality, which showed that over the entire 20th century the average mineral content of such vegetables as cabbage, lettuce, spinach and tomatoes (a fruit!), declined from 400mg to less than 50mg. (2)
In 2004 a report in the Journal of the American College of Nutrition examined food composition changes from 1950 to 1999 recorded in the USDA food composition tables. Forty-three crops were examined – mostly vegetables. The conclusion was that there were statistically reliable declines for 6 nutrients. The declines were observed in protein, calcium, phosphorous, iron, riboflavin and ascorbic acid. The declines were not insignificant. e.g. 6% in the case of protein and 38% for the B vitamin riboflavin. (3)
The UK publication Food Magazine early this year published an analysis of food quality changes in the UK over the period 1940-2002. The analysis was based on the well-known food composition tables published on a regular basis by McCance and Widdowson. (4) In an analysis of milk it was concluded that the iron content had fallen 62%, magnesium – another commonly deficient element, was down 21% and the copper content had disappeared completely. In the context of magnesium it is interesting to note that its levels fell in almost all foods examined – a mere 4% in turkey meat but dramatically lower quantities in many cheeses. Parmesan cheese was the worst affected recording a 70% fall in value. The calcium and iron content of all the foods examined was reduced dramatically in every instance e.g. the iron content of a beef rump steak fell 55%.
How can these changes be explained?
Are there any obvious causes for the general nutritional decline in food? Unfortunately, there appears to be no consensus on what the major factors could be. Indeed it is probable that multiple factors are at work. It is clear that the depleted nutritional value of many food items consumed today is an inherent feature of the foods chosen by consumers. A bottle of soda pop is clearly not as nutritious as a glass of milk or even a glass of pure fruit juice. Today's younger generation seem to prefer soda pop to milk.
Some nutritional changes can be explained by changes in access to foods, which are associated with trade related matters. In Britain, and probably in many other European countries dietary selenium levels have fallen dramatically in the last thirty years, to around half their earlier values. That decline appears to be due primarily to changes in trade regulations, which resulted in dramatic reductions of Canadian and US selenium-rich wheat imports. As a result, bread was produced from low selenium wheat of European origin. This illustrates how important nutritional changes can go unnoticed. Official exhortations to eat two or three pieces of bread each day do not address this problem.
Many modern farming practices lead to a reduction in quality. Grass-fed cattle produce meat that is much higher in nutrients like beta-carotene and vitamin E than their feedlot counterparts. Visit Jo Robinson's website for details – www.eatwild.com
Other nutritional changes can be attributed to changes in industrial practices. In the latest national food survey here in New Zealand (5) iodine was found to be the most deficient element. One reason for the reduced amount in dairy products relates to the declining use of Iodoform disinfectants on equipment used in the dairy industry.
Canadian researcher Harold Foster believes that pollution has resulted in chemical changes in soils, which affects the bio-availability of elements like selenium. Thus the plants grown on them are deficient in the nutrients concerned. He believes that selenium deficiency is a key factor in the current world AIDS epidemic and the increased prevalence of other viral diseases. (6)
One of the leading researchers in the field is Donald Davis, a biochemist at the University of Texas. He has been writing and speaking on the causes of declining food quality for years. At a recent meeting of the American Association for the Advancement of Science at St Louis he discussed the causes and possible solutions to the problem. Davis believes that the cause lies in the way food is grown, processed and prepared. He points out that the commercial imperatives of high-yield, fast growing crops result in a sacrifice of quality. He also observed that recent studies, (which have examined the effects on antioxidant levels of reversing these changes), have revealed that several organic growing methods can increase the broad antioxidant content of produce. Davis observes, "On average, antioxidant levels increased by about 30 percent in carefully designed comparative trials. Organically grown produce offers significantly enhanced health-promoting qualities, contributing to the achievement of important national public health goals." (7)
Are people today lacking key nutrients, which may be required for optimum health?
Unfortunately a consensus cannot be reached over what constitutes a deficiency - a very serious problem. The current guidelines issued by regulatory authorities worldwide appear to be mostly derived from historical estimates based on levels related to the prevention of clear and present disease danger. In other words, the recommendations ought to eliminate the risk of immediate disease for most of the population. Alas our long-term health prospects, resulting from the consumption of inadequate amounts of various nutrients over long periods, remain uncertain.
Many studies worldwide have concluded that a large percentage of people examined, are lacking in many nutrients. Perhaps the largest such analysis is presented in the US National and State Statistics. (8) It is clear that a large percentage of the US population are deficient in a wide variety of nutrients. The data records the percentage of people considered to be meeting the DRI values (see below). For example, over the entire US population 32% met the recommendation for magnesium, 9.6% for fibre consumption and 14.1% for vitamin E intake. Interestingly, only 51.7% met the vitamin C requirement. The most ubiquitous nutrient was selenium as 85.2% of people were judged to have an acceptable intake (there may, however, be some concerns over estimated selenium values, as mentioned in the next section). Many researchers feel that recommended intake levels could be grossly inadequate in any case. Thus one could argue that the current nutritional status of the US population, and presumably that of many other countries, is likely to be disastrously low.
How can we estimate our own nutritional deficiencies?
Nutritional advisors base their recommendations on officially established quantities of nutrients in commonly eaten foods. But just how relevant are these database values to the real world? A recently published study in the United States casts serious doubts about their value. (9) The research measured the selenium content of common foods grown in the US upper Midwest. It reported remarkable variations in selenium content for many foods. For example, the selenium content for wheat flakes varied 72-fold in their samples, 57-fold for wheat itself and 11-fold for beef. In particular, the study found that the values they recorded bore little resemblance to the figures provided by the USDA National Nutrient Database for Standard Reference. It was concluded that the differences were so great the reference base was of little value. One can only surmise that the same could be true for the nutrient content of many other foods in many other countries.
In order to identify a deficiency and potentially correct it, we have to have simple inexpensive tests to check our personal nutritional status for specific nutrients. Alas blood tests do not always answer that simple question. Some nutrients are primarily intra cellular. Some like iodine are probably best estimated by their excretion rates in urine. The science of personal nutritional estimation seems to be in its infancy!
We are all supposed to be cognisant of our own government's guidelines for vitamins and minerals (most other nutrients are not included to date). Terminology differs, as do recommendations in different jurisdictions. Unfortunately, the US has gone through a series of changes in terminology in the last 30 years, which challenge the most enthusiastic nutritional mind. The FDA established their RDAs (Recommended Daily Allowances) in 1973. The acronym is the same as the Recommended Dietary Allowances – the RDAs set up in 1941 by the National Academy of Sciences. The RDI system was then introduced – which refers to the Reference Daily Intake. After that the DRV (Daily Reference Value) system was added. Then the system, which currently appears on US food labels, was introduced. It was called the DVs or Daily Values. This was followed in the late 1990's by the Food and Nutrition Board of the Institute of Medicine, who introduced another system called DRIs (Dietary Reference Intakes). The icing on the cake is the UL system (upper safe limits), which seems to be the only one that is not related to minimum desirable amounts! Perhaps the ability to memorise and understand the above information could be used as a test for incipient dementia!
When one looks at the large array of traditionally accepted nutrients - primarily the vitamins and minerals, there is no international consensus on how much we should take to ward off incipient disease or treat that which is present. (In many countries the only officially permitted treatment for a disease is a prescription medicine provided by the pharmaceutical industry). The recommended nutrient values determined by committees worldwide seem to reflect values based on minimum rather than maximum desirable quantities. Such committees seem to believe that over consumption of nutrients is a far greater danger than under consumption. Yet it is hard to find reports of excessive food supplement consumption having resulted in undesirable effects.
Should governments add extra nutrients to common foods to improve our health?
In the late 19th century technological progress lead to "advances" in the production and processing of flour, the refining of oils to allow the development of butter substitutes and much else besides. Since then our health authorities have virtuously added missing nutrients (the ones removed in the advanced technical processes) with some success. (See Henry Schroeder's book - The Trace Elements and Man). (10) US deaths from pellagra in 1938 were recorded as 2300 and dropped to near zero in the following 20 years with the addition of vitamin B3 (niacin) to bread. Another added nutrient has been iodine, which is usually added to salt to prevent goitre. The modern identification of the disease has been linked to the Goyt valley in Northern England where the iodine-insufficient inhabitants suffered from swollen thyroid glands – Derbyshire neck. The original calculations used in the UK to determine the amount of iodine to be added to salt were based on average daily consumption estimates of 10 grams of sodium chloride. Current health recommendations target salt intakes of less than half that amount. Unfortunately the addition of iodine to salt has been inconsistent internationally. Some countries like Canada have made its addition to all salt compulsory. Others have required it to be added only to the discretionary salt available in the supermarket for addition to food during and after cooking. Many health conscious consumers now avoid the practice as they strive for a lower salt diet.
It seems that health authorities worldwide treat deficiencies, which are readily recognisable sources of disease, much more decisively than those whose longer term effects remain uncertain. Here in New Zealand we have our own unique set of circumstances. No doubt readers elsewhere will face different challenges. Our environment is lacking primarily in selenium, boron and iodine. Interestingly the selenium status of people in our South Island is worse than residents of the North Island. This is because South Island bread is produced from local selenium deficient wheat, while North Island bread is largely produced from wheat imported from Australia and Canada, which is high in selenium. It illustrates a very important principle. You cannot equate the consumption of a specific food product with adequate intake of a key element contained in it. It also shows that national legislation designed to provide adequate access to any nutrient, even in a small country like New Zealand, can be seriously flawed.
In Australia most areas have soils abundant in selenium. Australians obtain a large part of their total selenium by eating bread-related products. Clearly an adequate selenium intake there is dependent on bread consumption. Gluten sensitive Australians beware!
As a retired member of the dental profession I am well aware that the issue of fluoridation has divided society. I have never taken sides in the issue but it is clear that the fluoridation of water and toothpaste results in a situation where it cannot be predicted how much fluoride any one person is imbibing. Any form of 'mass medication' has its limitations. Yet the recent addition of folic acid to bread-related products in a small number of countries appears to be producing a range of benefits. The latest such report concludes that stroke mortality has fallen in both Canada and the US as the result of food folate fortification. (11)
How can we redress the balance and ensure optimum nutrition for our families and ourselves?
Mass medication and government control are not popular measures, but it does seem that if we are to redress the current problems in the quality of food we have to accept fortification of some foods. Hopefully, commercial forces will result in new nutritionally enhanced foods becoming widely available. Plants are now being developed to contain higher levels of nutrients than those commonly available today. We have to remember that the food constituents which have been identified as essential or beneficial are made up primarily of vitamins and minerals. There is now a growing awareness that many other substances in food are key to health. It may take many years to identify all of them and ensure they can be consumed in sufficient quantities necessary for optimum health. Today organic food attracts premium prices. There is a growing belief that organic foods are more nutritious and contain less chemical residues than their counterparts being sold in our mass production food system. Many of us do not have access to a wide variety of organic foods, or we cannot afford the extra costs involved. Perhaps designer food will, in the future, attract only a small premium and be more nutritious than the food on sale today. Until that day arrives the fortification of regular food with a variety of necessary constituents seems essential. The simultaneous consumption of comprehensive nutritional supplements would also appear to be a wise precaution if we are to aim for optimum health throughout our lives.