Nutrients in our food are decreasing

I recently read a blog entitled “Food is less nutritious than it used to be”. Consuming a range of bioavailable and micronutrientnutrient-dense foods is important to me, so this article struck a nerve. However, when I dug into a couple of its source papers, I did not agree with how they had been summarized.

I decided to do my own research, and this is what I found.

“…the micronutrient content of a range of fruits, vegetables, meats, and dairy products does appear to be declining”

I’m going to present the following:

• Evidence for a decline of micronutrients in real food and likely causes

• Potential implications of real food micronutrient decline

• Practices I employ to get enough micronutrients

Evidence for a decline of micronutrients in real food and likely causes

There are three ways to consider changes in the micronutrient content of our food, namely the overall qualitative direction, the amounts reported in certain fruit and veg and the amounts reported in meats and dairy (see Appendix I for a description and significance of data presented).

Directional drop in all food products across the world

Looking at all of the data, it is clear that in most of the geographic areas studied, and over most time periods, there is a drop in micronutrient content in a range of fruit, veg, meat, and dairy. 85% of the entries in Table 1 show a decline, 11% show an increase, and 3% suggest no change in micronutrient content.

The Australian data collected between the 1980s and 2000 is equivocal but it is the exception. A broad pattern of decline is evident in the industrialised world represented by Europe and the United States.

Quantifiable drop in fruit and veg micronutrients between 1940 and 2019

The results for fruit and veg reported by Mayer et al for the period 1940-2019 [1] (represented in top row in Table 1) are worth digging into. They report that, in the UK, the levels of sodium, iron, zinc, and magnesium decreased by 52%, 50%, 49%, and 10% respectively over the 79-year period. Those results are statistically significant (Appendix I).

Quantifiable drop in meat and dairy micronutrients between 1940 and 2002

It is also possible to take a closer look at the UK meat and dairy product data collected for the period 1940 – 2002 [3] represented in Table 1. When averaged across all products (meats, cheese, and milk), the declines in micronutrients range from large at 52% (iron), through a mid-range group at 19% to 24% (potassium, calcium, magnesium, phosphorous, and zinc) to small at 4% (sodium).

In summary, the micronutrient content of a range of fruits, vegetables, meats, and dairy products does appear to be declining. Furthermore, our fruit, veg, meat and dairy contain about half the amount of important micronutrients that were available to our grandparents.

Table 1:  Changes in micronutrient concentrations in Europe, USA and Australia.  Green = increase, Amber = no change, Red = decline

Changes in plant and animal varieties, and changes in agricultural practices are discussed by a number of authors. I offer below an additional take on the impact on the soil microbiome.

Changes in plant and animal varieties

Several authors describe how since the 1960s agricultural revolution, farmers have focused on a few new crop and animal varieties to increase yield (e.g., tonnage or calories per acre) to feed the world’s growing population [1,3,4]. It must be said that we have succeeded in our objective of essentially increasing calories per acre and that has to be a good thing. It does appear, however, that in so doing, we may have reduced or diluted the micronutrient content of that food.

Changes in agricultural practices

Alongside changes to crop and animal varieties since the 1960s, farmers have intensified their practices with the use of heavier machinery, synthetic fertilisers, and synthetic pesticides. These have also increased yield [1,3,4].

However, even in soil-based systems, those practices are less agro-ecological than what preceded them. A worst case scenario is represented by soil-less or hydroponic practices in which crops are completely isolated from nature’s ability to provide plants with the nutrients they need to grow naturally [1].

Changes in soil microbiology

Growing fewer crop and animal varieties plus using more industrial agricultural techniques are less ecologically sensitive. Reductions in above-ground plant diversity (monocrops), fewer animal types, and reliance on plowing and chemicals, have reduced the diversity of the soil microbiome. This in turn reduced the likelihood of crops and animals receiving their full potential of micronutrients from the soil they are growing in [5,6].

Potential implications of real food micronutrient decline

There is good evidence to suggest that when micronutrients are scarce, our body allocates them to processes that ensure short-term survival rather than long-term health [7]. This may explain why micronutrient deficiencies are associated with a range of so-called chronic diseases [8], such as elevated blood pressure, heart disease, cancer, and cognitive dysfunction [7].

It may be the case that we are getting enough micronutrients to satisfy our immediate needs, but not our long-term health. Our bodies are making sure that they use micronutrients to take care of business in the short-term. Therefore, we are not alert to the risks of micronutrient deficiencies because it is only in the long-term that shortages show up in what we’ve grown used to thinking of as chronic diseases.

“Real food from modern agriculture in advanced economies such as Europe and USA contains fewer micronutrients than it did in our grandparents’ day”

Practices I employ to get enough micronutrients

It’s well known now that getting enough bioavailable micronutrients is important and best achieved by consuming a range of real foods, including meat products, if acceptable.

Overall, despite what I’ve recently discovered, my approach to micronutrient consumption hasn’t changed. I continue to abide by the following principles:

• Identify real foods that are a high density source of bioavailable nutrients

• Grow vegetables using practices likely to boost micronutrient content

• Source other food locally that is grown regeneratively

• Prepare foods in a way that preserves their micronutrients

• Take a supplement where necessary

• Avoid harm - food from feed lots, fish farms, and mono-crops

• Avoid harm – seed oils and other industrially processed products

“...so-called chronic diseases may instead be outward signs of long-term, slow onset malnutrition”

Summary

Real food from modern agriculture in advanced economies such as Europe and USA contains fewer micronutrients than it did in our grandparents’ day. This may be an unexpected consequence of adopting modern agricultural practices some 80 years ago intended to feed our expanding population. We appear to have succeeded in our objective at the expense of micronutritional quality.

Long-term micronutrient deficiency can be viewed similarly to processed carbohydrates and seed oils as one of the factors associated with what we have traditionally thought of as chronic disease [9]. There is mounting evidence that many so-called chronic conditions are not in fact diseases. Many of them may instead be metabolic responses to the food we have chosen to consume. Put differently, so-called chronic diseases may instead be outward signs of long-term, slow onset malnutrition [1, 10].

The good news is that it is possible to ensure adequate consumption of micronutrients. I try to follow the simple principles of seeking a diversity of real foods and supplement where it makes sense. Our bodies and microbiome have evolved a wondrous ability to sustain us through myriad changing circumstances. Our job is to do no harm and give ourselves the nutrition we need to benefit from what evolution has given us.

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References

1. Mayer AB, Trenchard L, Rayns F. Historical changes in the mineral content of fruit and vegetables in the UK from 1940 to 2019: a concern for human nutrition and agriculture. Int J Food Sci Nutr. 2022 May;73(3):315-326. doi: 10.1080/09637486.2021.1981831. Epub 2021 Oct 15. PMID: 34651542

2. Eberl, E.; Li, A.S.; Zheng, Z.Y.J.; Cunningham, J.; Rangan, A. Temporal Change in Iron Content of Vegetables and Legumes in Australia: A Scoping Review. Foods 2022, 11, 56. https://doi.org/10.3390/foods11010056

3. Thomas D. The mineral depletion of foods available to us as a nation (1940-2002)--a review of the 6th Edition of McCance and Widdowson. Nutr Health. 2007;19(1-2):21-55. doi: 10.1177/026010600701900205. PMID: 18309763

4. Davis, D. R. (2009). Declining Fruit and Vegetable Nutrient Composition: What Is the Evidence?. HortScience horts, 44(1), 15-19. Retrieved Sep 8, 2023, from https://doi.org/10.21273/HORTSCI.44.1.15

5. Montgomery, D. and Bikle, A. (2016) The hidden half of nature: The microbial roots of life and health. London: Norton and Company

6. Montgomery, D. and Bikle, A. (2022) What your food ate: How to heal our land and reclaim our health. London: Norton and Company

7. Ames BN. Low micronutrient intake may accelerate the degenerative diseases of aging through allocation of scarce micronutrients by triage. Proc Natl Acad Sci U S A. 2006 Nov 21;103(47):17589-94. doi: 10.1073/pnas.0608757103. Epub 2006 Nov 13. PMID: 17101959; PMCID: PMC1693790

8. Dinicolantonio, D. and Land, S. (2021) The Mineral Fix ; How to optimize your mineral intake for energy, longevity, immunity, sleep and more. John Wiley & Sons

9. Hussey,S.H (2022) Understanding the Heart: Surprising insights into the evolutionary origins of heart disease – and why it matters. White River Junction, VT: Chelsea Green Publishing

10. Phillips MC. Metabolic Strategies in Healthcare: A New Era. Aging Dis. 2022 Jun 1;13(3):655-672. doi: 10.14336/AD.2021.1018. PMID: 35656107; PMCID: PMC9116908

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Appendix I

Data presented

In Table 1 I’ve summarized data from three publications [1 - 3] which present micronutrient data for fruit, veg, meat and dairy products from Europe, USA and Australia. Most of the study periods are quite long (79 years is the longest) although one of the Australian investigations looked at just 20 years.

Reference 1 contains a summary table of data from Europe, Australia and USA which provided directional (e.g., increase, decrease, or no change) data for the regions covered. I did not dig further into those studies but do represent them as directional in Table 1. Increases in concentration are green, no change is amber, and a reduction is red. If a section of Table 1 is blank, it just means that there is no data for that entry.

I was able to look at some quantifed data from reference 1 and all of it in reference 3.

Statistical significance

The publications summarized in Table 1 present their data in different ways so we need to be careful about how I represent them. Sometimes the results are what is called “statistically significant”, sometimes not. A statistically significant result is one in which the author has been able to say with particular confidence that a result is likely to be a real one. A statistically insignificant result is one in which we have less confidence because it could be caused by factors (e.g., the variable ways in which products were analysed) other than the one we’re interested - a real change in micronutrient content.

For example, if we look at the very first row in Table 1, we see that sodium, potassium, calcium, magnesium, iron, and copper are all coloured red, meaning that between 1940 and 2019, their values were measured as having dropped. However, the authors of the paper point out that those drops are only statistically significant for sodium, magnesium, iron, and copper. This means that the potassium and calcium levels measured may be for reasons other than an actual drop in their values.

Because the authors don’t always make clear whether or not their data is statistically significant, I chose to present everything as directional in Table 1. I can still draw conclusions from patterns in direction.