Bigger Harvests, Emptier Food: Why Your Vegetables Have Fewer Minerals Than in 1950

Patrick Quillin, PhD,RD,CNS

There is a region in China where the soil is so deficient in selenium that the people there often develop a degeneration of the heart, known as Keshan’s disease, and only curable with selenium. There are dozens of similar examples of unnecessary suffering as humans ignore our reliance on the earth for minerals. There is a remarkable relationship between the minerals beneath our feet and the biochemical processes that sustain human life.

From Rock to Soil to Human: The fascinating journey of minerals into the human body, and their effect on health and longevity.

We Are, Quite Literally, Made of the Earth

The calcium in our bones, the magnesium that helps regulate hundreds of enzymatic reactions, the zinc that supports immune function, the selenium incorporated into antioxidant enzymes, and the iron that transports oxygen through our bloodstream all have something in common:

They originated in the Earth

Plants absorb mineral nutrients from soil and water. Animals obtain minerals by consuming plants, other animals, soil, and water. Humans obtain these elements through the food chain and drinking water.

While the soil around the earth varies in mineral content by up to 20 fold, the minerals in the ocean are relatively constant and evenly distributed. Think of the homogenous distribution of ingredients when you puree something, versus those separate ingredients in your refrigerator or on your dinner plate.

Plants create glucose from the energy of the sun through photosynthesis by combining carbon dioxide and water. From that amazing reaction, plants then proceed to create thousands of phytochemicals, bioflavonoids, carotenoids, polyphenols, and more. But even plants cannot create minerals. They and us must obtain minerals from the earth. We cannot manufacture magnesium, zinc, selenium, or any other chemical element through human metabolism.

Natural Cancer Treatment: Popular Alternatives

We must obtain them from our environment.

This leads to an important nutritional question:

Can we reasonably expect optimal human nutrition from food grown in soil managed primarily for maximum agricultural yield rather than maximum nutritional quality?

The answer requires an examination of human biochemistry, plant physiology, soil microbiology, modern agricultural practices, and the scientific evidence concerning mineral deficiencies.

One conclusion is particularly important:

A crop can appear healthy, produce an excellent harvest, and still contain less of certain minerals than the people consuming it would ideally obtain.

However, mineral content is not determined by soil concentration alone. Genetics, soil pH, mineral availability, microbial activity, environmental conditions, and interactions among nutrients all influence the final nutritional composition.

PART I. THE ESSENTIAL MINERALS IN HUMAN NUTRITION

Scientists generally recognize approximately 15 mineral elements as essential to human nutrition, depending on how essentiality is classified.

An essential mineral is one whose absence produces an identifiable impairment of normal biological function that can be corrected by restoring that mineral.

1. The Major Minerals

These are required in comparatively large quantities.

Mineral	Adult daily recommendation*	Principal functions
Calcium	1,000–1,200 mg	Bones, teeth, muscle contraction, cell signaling
Phosphorus	700 mg	ATP, DNA, RNA, cell membranes, bones
Magnesium	310–420 mg	Enzymes, ATP metabolism, nerve and muscle function
Potassium	2,600–3,400 mg	Cellular electrical activity, blood pressure regulation
Sodium	1,500 mg AI	Fluid balance, nerve impulses
Chloride	2,300 mg AI	Gastric hydrochloric acid, fluid balance
Sulfur	No separate RDA	Sulfur-containing amino acids, glutathione, connective tissue

Values are typical U.S. adult RDAs or Adequate Intakes. Requirements vary by age and sex. Calcium requirements increase to 1,200 mg for men over 70 and women over 50. Potassium values are AIs rather than RDAs.

Sulfur is essential, but its requirement is generally satisfied through sulfur-containing amino acids and other dietary compounds rather than through a separate mineral intake recommendation.

An interesting observation

The adult body contains approximately:

1,000–1,200 grams of calcium.
500–700 grams of phosphorus.
20–28 grams of magnesium.
120–150 grams of potassium.

The precise quantities vary with body size and composition.

Most calcium resides in the skeleton. Most potassium resides inside cells.

Magnesium occupies a particularly interesting position because only a small fraction circulates in the bloodstream.

Consequently, a normal serum magnesium concentration does not necessarily establish that total-body magnesium stores are optimal.

2. The Essential Trace Minerals

These are required in milligram or microgram quantities.

Mineral	Adult RDA or AI	Principal functions
Iron	8–18 mg	Hemoglobin, mitochondrial respiration
Zinc	8–11 mg	Hundreds of enzymes, immunity, DNA synthesis
Copper	900 µg	Connective tissue, iron metabolism, antioxidant enzymes
Manganese	1.8–2.3 mg AI	Enzymes, cartilage formation, metabolism
Selenium	55 µg	Selenoproteins, thyroid metabolism, antioxidant defense
Iodine	150 µg	Thyroid hormones
Molybdenum	45 µg	Sulfite oxidase and other enzymes
Chromium	25–35 µg AI	Historically associated with glucose metabolism; essentiality is disputed
Fluoride	3–4 mg AI	Dental enamel resistance to decay; not established as essential for human life

Two qualifications deserve attention.

Chromium: Trivalent chromium was traditionally classified as essential because of proposed effects on insulin signaling. However, its essentiality in humans is increasingly questioned.

Thus, lists of essential minerals vary depending on whether they include elements with established benefits but uncertain biological essentiality.

Mineral requirements and the difference between deficiency prevention and optimal function

The RDA is designed to meet the requirements of approximately 97–98% of healthy individuals in a specified population group.

It is not necessarily the intake that maximizes every conceivable biological outcome.

Nevertheless, it would be scientifically incorrect to assume that substantially exceeding an RDA automatically improves health.

The nutritional objective is adequacy and physiological balance, not maximum mineral intake.

PART II. MINERALS THAT MAY BE ESSENTIAL OR CONDITIONALLY BENEFICIAL

The distinction between essential and beneficial deserves careful attention.

An element may influence human physiology without having a demonstrated dietary requirement.

3. Boron

Boron is one of the most interesting candidates for further nutritional research.

Sources

Boron is present in:

Prunes and raisins.
Avocados.
Nuts.
Legumes.
Fruits.
Vegetables.
Drinking water.

Dietary intake commonly falls around 1–3 mg daily, although intake varies considerably.

Biological effects

Research suggests that boron may influence:

Calcium and magnesium metabolism.
Bone mineralization.
Vitamin D metabolism.
Inflammatory signaling.
Steroid hormone metabolism.
Certain aspects of cognitive performance.

Small human studies have reported changes in inflammatory markers and mineral metabolism with boron supplementation.

However, these studies have not established that boron supplementation prevents osteoporosis, improves cognition, or extends lifespan.

Boron is essential for higher plants because it participates in cell-wall structure and growth.

Its essentiality in humans remains unproven.

PMC research:
Nothing Boring About Boron — Integrative Medicine review

4. Lithium

Lithium is another intriguing element.

It occurs naturally in:

Soil.
Drinking water.
Vegetables.
Grains.
Certain mineral waters.

Trace amounts of lithium are routinely consumed through food and water.

Lithium can influence intracellular signaling pathways, including glycogen synthase kinase-3.

At pharmacological doses, lithium salts are established treatments for certain psychiatric disorders.

At much lower environmental concentrations, researchers have investigated possible associations with:

Mood regulation.
Neuroprotection.
Suicide rates.
Cognitive decline.
Alzheimer’s disease.

Some ecological studies have reported associations between lithium concentrations in drinking water and lower suicide rates.

There is currently no established human RDA for lithium.

PMC research:
Lithium in Drinking Water and Suicide Prevention — PMC search

5. Silicon

Silicon is abundant in the Earth’s crust.

Humans consume it primarily through:

Whole grains.
Cereals.
Certain vegetables.
Drinking water.
Beer.

Dietary silicon is often present as soluble orthosilicic acid.

Researchers have investigated its potential involvement in:

Collagen formation.
Bone mineralization.
Connective tissue integrity.
Skin and hair structure.

Some observational studies associate greater silicon intake with higher bone mineral density.

Its importance in certain plants, especially grasses, is much better documented.

6. Vanadium

Vanadium occurs naturally in soil and food.

It has attracted scientific interest because some vanadium compounds demonstrate insulin-like activity under experimental conditions.

Animal experiments have shown effects on glucose metabolism.

There is no established human dietary requirement.

7. Nickel

Nickel is essential for certain microorganisms and plants because it participates in enzymes such as urease.

It may have biological roles in animals, but a specific essential requirement in humans has not been demonstrated.

Nickel is present in legumes, grains, nuts, and chocolate.

Excess exposure can cause adverse effects, and nickel is a common cause of contact dermatitis.

PART III. NATURALLY OCCURRING MINERALS WITH UNCERTAIN HUMAN FUNCTIONS

The Earth’s crust contains dozens of elements that enter the food chain in trace amounts.

Their presence in human tissue does not necessarily mean they serve an essential biological purpose.

8. Elements of Scientific Interest

Element	Natural occurrence	Evidence concerning human nutrition
Rubidium	Soil, plants, drinking water	No established essential function
Cesium	Soil and trace amounts in foods	No established nutritional requirement
Strontium	Soil, water, vegetables	Can enter bone; not established as essential
Germanium	Soil and some plants	No established essential function
Tin	Food and environmental sources	No established human requirement
Aluminum	Soil, water, foods	No known essential biological role
Barium	Soil and water	No known essential role; soluble salts can be toxic
Gold	Trace environmental exposure	No established nutritional role
Silver	Environmental exposure	No established nutritional role
Titanium	Soil and environmental exposure	No established nutritional requirement

Rubidium

Rubidium is chemically similar to potassium.

It can interact with certain potassium transport systems.

Researchers have investigated its distribution in tissues and possible effects on neurological function.

Cesium

Cesium also resembles potassium chemically.

It can interact with cellular ion transport.

Importantly, some alternative cancer therapies have promoted high-dose cesium chloride.

Strontium

Strontium is particularly interesting because it can substitute for calcium in bone mineral.

Certain pharmaceutical strontium compounds have been investigated for osteoporosis.

Germanium

Germanium has occasionally been marketed as an immune-enhancing trace mineral.

Some organic germanium compounds have been investigated experimentally.

The important distinction

There are three fundamentally different propositions:

An element occurs naturally in food.
An element influences human physiology.
An element is essential for human health.

The first does not establish the second, and the second does not establish the third.

PART IV. SOIL: THE FOUNDATION OF THE HUMAN FOOD CHAIN

9. What Is Soil?

Healthy agricultural soil is much more than pulverized rock.

It is a complex biological ecosystem containing:

Mineral particles.
Organic matter.
Water.
Air.
Bacteria.
Fungi.
Protozoa.
Nematodes.
Earthworms.
Plant roots.
Decomposing organic material.

The mineral component originates largely from the weathering of rocks.

Granite, basalt, limestone, shale, and other geological formations contain different elemental compositions.

Over thousands of years, physical weathering, chemical reactions, and biological processes release mineral ions.

Plant roots absorb these ions from soil water.

For example:

Magnesium in mineral particles → dissolved Mg²⁺ → root absorption → chlorophyll and enzymes → food → human magnesium metabolism.

The pathway is elegant, but it is not automatic.

A mineral may be abundant in the soil yet poorly available to plants.

This brings us to one of the most important subjects in agricultural nutrition.

PART V. SOIL pH AND MINERAL BIOAVAILABILITY

10. Why pH Matters

Soil pH measures the acidity or alkalinity of the soil environment.

The pH scale is logarithmic.

A soil with pH 5 contains approximately 100 times the hydrogen ion activity of soil at pH 7.

Soil pH influences:

Mineral solubility.
Root physiology.
Microbial activity.
Nutrient interactions.
Aluminum toxicity.
Phosphorus availability.

General nutrient availability

Soil pH	Common nutritional considerations
Below 5.0	Aluminum and manganese toxicity become more likely; calcium and magnesium may be depleted
5.0–5.5	Many crops experience reduced nutrient availability
5.5–6.0	Suitable for some acid-loving crops
6.0–7.0	Favorable for many vegetables and agricultural crops
7.0–7.5	Many nutrients remain available; iron and manganese availability may decline
Above 7.5	Iron, zinc, manganese, and phosphorus deficiencies become more likely

These are general patterns, not universal rules.

Blueberries, for example, prefer considerably more acidic soil than many vegetables.

Manage your acidic body

Magnesium and pH

Magnesium is absorbed by plant roots as Mg²⁺.

Acidic soils may become magnesium deficient because rainfall and irrigation can leach magnesium from the root zone.

In highly acidic soils, aluminum toxicity can also interfere with root development.

At the opposite extreme, alkaline soils may contain magnesium but exhibit nutrient imbalances involving calcium, potassium, or other cations.

Excess potassium fertilization can reduce magnesium uptake in certain crops.

Thus, magnesium nutrition depends on more than its absolute concentration.

The ratios and interactions among magnesium, calcium, potassium, and other nutrients matter.

Dark chocolate is a great source of magnesium plus it has many other health benefits

Can fertilizers change soil pH?

Absolutely.

Certain nitrogen fertilizers, particularly ammonium-based fertilizers, can acidify soil over time.

As ammonium is converted to nitrate through nitrification, hydrogen ions are produced.

Conversely, nitrate uptake and some other agricultural processes can increase rhizosphere pH.

Lime is commonly used to raise the pH of acidic soils.

Elemental sulfur is sometimes used to lower the pH of alkaline soils.

However, soils containing substantial free calcium carbonate can resist attempts to lower pH.

The correct strategy is not to make all soils neutral. It is to establish the pH appropriate for the crop and its root environment.

PART VI. MODERN AGRICULTURE: MAXIMUM YIELD VERSUS MAXIMUM NUTRITION

11. What Minerals Do Farmers Typically Add?

Modern commercial agriculture has been enormously successful at increasing crop production.

Its foundation has traditionally been the application of three major nutrients:

N–P–K

Nitrogen.
Phosphorus.
Potassium.

These are the three numbers commonly printed on fertilizer bags.

For example, 10-10-10 fertilizer contains:

10% nitrogen, 10% available phosphate expressed as P₂O₅, and 10% soluble potash expressed as K₂O.

These nutrients are essential for plant growth.

However, they are not the only nutrients plants require.

Essential plant nutrients

Plants generally require 17 essential elements.

They obtain carbon, hydrogen, and oxygen primarily from air and water.

The remaining 14 mineral nutrients are:

Macronutrients: nitrogen, phosphorus, potassium, calcium, magnesium, sulfur.

Micronutrients: iron, manganese, zinc, copper, boron, molybdenum, chlorine, nickel.

Commercial fertilizers may include many of these elements, depending on soil testing and crop requirements.

It would therefore be inaccurate to say that modern farmers never add magnesium, zinc, copper, or other trace elements.

They frequently do.

However, the economic incentive to correct a nutrient deficiency that reduces yield is often stronger than the incentive to improve the nutritional composition of food without increasing yield.

That distinction is central to this report.

12. The Hidden Hunger of Plants

Agronomists use the term hidden hunger to describe a situation in which a plant experiences a nutrient deficiency without displaying obvious symptoms.

The deficiency may reduce growth or yield before visible symptoms develop.

A related phenomenon can occur when a crop produces an acceptable harvest but has a lower concentration of a nutrient important to humans.

Selenium provides an especially revealing example.

Selenium is essential for humans and many animals.

However, selenium is not generally considered essential for higher plants.

Consequently, a crop can grow normally in selenium-poor soil while providing very little selenium to the people consuming it.

This creates an important nutritional disconnect:

A mineral may be essential to the consumer without being essential to the crop.

Iodine presents a somewhat similar challenge.

Plants can absorb iodine, and certain concentrations may benefit some species, but iodine is not universally recognized as essential for higher plants.

Therefore, crop yield alone cannot guarantee adequate iodine nutrition.

PART VII. HAVE OUR SOILS BECOME DEPLETED?

13. The Scientific Evidence

There is a popular assertion that modern agricultural soils have lost most of their mineral content.

The reality is more complicated.

Some soils have experienced substantial nutrient depletion through:

Continuous harvesting.
Erosion.
Leaching.
Inadequate replacement of removed nutrients.
Loss of organic matter.
Poor irrigation practices.
Soil acidification.
Salinization.

However, other agricultural soils contain abundant mineral nutrients, including substantial reserves of phosphorus, potassium, calcium, or magnesium.

In some regions, excessive fertilization has produced nutrient accumulation and environmental pollution.

It is therefore scientifically inaccurate to describe all modern agricultural soils as uniformly depleted.

Have fruits and vegetables lost nutritional value?

Several studies have compared historical food composition data with modern measurements.

Some have reported declines in selected nutrients.

A frequently discussed study by Donald Davis and colleagues examined changes in the nutritional composition of 43 garden crops between 1950 and 1999.

The researchers reported statistically significant declines in several nutrients, including calcium, phosphorus, iron, riboflavin, and ascorbic acid.

However, the study could not establish that soil depletion was the principal cause.

Possible explanations include:

Changes in crop varieties.
Selection for higher yields.
Differences in analytical methods.
Changes in growing conditions.
The dilution effect.

The dilution effect

Suppose an older tomato variety produces 100 grams of fruit containing 1 mg of a mineral.

A modern variety produces 150 grams but contains only 1.1 mg of that mineral.

Total mineral accumulation has increased by 10%.

However, mineral concentration per 100 grams has declined by approximately 27%.

The plant is producing more biomass faster than it is accumulating that particular mineral.

This is one reason higher agricultural yields do not always translate into higher nutrient density.

PMC research:
Changes in USDA Food Composition Data for 43 Garden Crops, 1950–1999

PART VIII. SELENIUM AND KESHAN DISEASE IN CHINA

14. A Remarkable Example of Geography Determining Human Health

Keshan disease provides one of the clearest historical examples of a relationship between soil mineral composition and human disease.

The condition was recognized in parts of China, particularly in regions with exceptionally low environmental selenium.

It was named after Keshan County in Heilongjiang Province.

What is Keshan disease?

Keshan disease is an endemic cardiomyopathy.

Affected individuals can develop:

Heart muscle injury.
Cardiac enlargement.
Arrhythmias.
Heart failure.
In severe cases, sudden death.

Historically, children and women of childbearing age were particularly affected in endemic regions.

The selenium connection

Researchers found that selenium concentrations in local soil, crops, and human tissues were unusually low.

Selenium is incorporated into selenoproteins, including glutathione peroxidases.

These enzymes help regulate oxidative damage.

Selenium deficiency can weaken antioxidant defenses in cardiac tissue.

However, selenium deficiency alone does not fully explain Keshan disease.

Research also implicates viral infection, particularly coxsackievirus, and potentially other environmental and nutritional factors.

Selenium supplementation

Public-health interventions that improved selenium intake were associated with major reductions in Keshan disease incidence.

This remains an important example of geographically determined nutritional disease.

But it would be an oversimplification to conclude that every selenium-deficient individual develops cardiomyopathy.

The disease appears to involve multiple interacting factors.

The broader lesson

Selenium is not required for normal growth in most higher plants.

Consequently, crops can appear healthy while supplying insufficient selenium to humans.

The farmer may see a successful harvest while the nutritionist sees a potentially deficient food supply.

PMC research:
Keshan Disease and Selenium — National Library of Medicine research

PART IX. AUSTRALIA: SWAYBACK DISEASE AND COPPER DEFICIENCY

15. When the Animals Revealed What Was Missing From the Soil

The Australian experience offers another important chapter in the history of mineral nutrition.

Sheep farmers observed a neurological disorder commonly called swayback.

Affected lambs could exhibit:

Weakness.
Poor coordination.
Difficulty standing.
Abnormal gait.
Paralysis.
Severe neurological injury.

The condition is also known as enzootic ataxia.

What caused swayback?

The major nutritional cause was copper deficiency.

Copper is required for enzymes involved in:

Connective tissue formation.
Iron metabolism.
Mitochondrial energy production.
Antioxidant defense.
Nervous-system development.

In developing lambs, inadequate copper availability can interfere with normal formation and maintenance of nervous tissue.

Soil and dietary interactions

The problem was not always simply a lack of copper in the soil.

Copper availability to grazing animals can also be reduced by excessive dietary molybdenum and sulfur.

In the rumen, molybdenum and sulfur can form thiomolybdates that interfere with copper absorption and metabolism.

Thus, animals can become functionally copper deficient even when their feed contains measurable copper.

An important distinction: cobalt deficiency

Australia and New Zealand also experienced major livestock problems associated with cobalt deficiency.

Cobalt is required by rumen microorganisms to synthesize vitamin B12.

Cobalt-deficient grazing animals may develop:

Poor appetite.
Weight loss.
Anemia.
Poor growth.
General unthriftiness.

Historically, cobalt deficiency was associated with conditions such as bush sickness and coast disease.

Swayback is primarily associated with copper deficiency.

Cobalt deficiency produces a different syndrome involving inadequate vitamin B12 synthesis.

Why this matters to humans

These examples demonstrate that:

Soil mineral composition influences forage composition.
Forage composition influences animal nutrition.
Mineral interactions influence biological availability.
Nutritional disease can develop even when animals receive adequate calories and protein.

An additional caution is important: sheep are unusually susceptible to copper toxicity. Mineral supplementation in livestock must be species-specific.

PMC research:
Copper Deficiency and Swayback in Sheep

Cobalt Deficiency and Vitamin B12 in Ruminants

PART X. MAGNESIUM: THE FORGOTTEN MINERAL?

16. Why Magnesium Deserves Special Attention

Magnesium participates in an extraordinary range of biochemical reactions.

It is required for normal function of enzymes involved in:

ATP metabolism.
DNA and RNA synthesis.
Protein synthesis.
Neuromuscular function.
Glucose metabolism.
Blood pressure regulation.
Cellular signaling.

ATP generally functions biologically as a magnesium-ATP complex.

Thus, magnesium is deeply involved in cellular energy metabolism.

Symptoms of Magnesium Deficiency

Magnesium and chlorophyll

Magnesium occupies the central position in the chlorophyll molecule.

Without magnesium, plants cannot maintain normal photosynthetic function.

This makes magnesium essential to both plant and animal life, although its biochemical functions differ.

How many Americans consume adequate magnesium?

National dietary surveys have consistently found that a substantial proportion of Americans consume less magnesium than their Estimated Average Requirement.

The frequently cited figure is approximately 48%, although the percentage varies by age, sex, and survey period.

An intake below the EAR indicates increased probability of inadequacy, not necessarily an established clinical deficiency.

Older adults are among the groups at risk of inadequate intake.

Magnesium-rich foods

Food	Approximate magnesium per serving
Pumpkin seeds, 1 oz	150–160 mg
Chia seeds, 1 oz	95–110 mg
Almonds, 1 oz	75–80 mg
Spinach, cooked, ½ cup	75–80 mg
Cashews, 1 oz	70–75 mg
Black beans, cooked, ½ cup	55–65 mg
Dark chocolate, 1 oz	50–65 mg
Avocado, 1 medium	50–60 mg

Values vary by variety, processing, and growing conditions.

Do farmers add magnesium?

Yes.

Magnesium is routinely supplied where soil tests or crop symptoms indicate a need.

Common sources include:

Dolomitic limestone: Supplies calcium and magnesium while raising soil pH.

Magnesium sulfate: Supplies magnesium and sulfur without substantially raising pH.

Magnesium oxide: Supplies magnesium and can have a liming effect.

Potassium magnesium sulfate: Supplies potassium, magnesium, and sulfur.

However, magnesium is not necessarily included in every commercial fertilizer program.

Where soils already contain sufficient magnesium for plant growth, additional magnesium may not increase crop yield.

The more challenging research question is whether carefully managed magnesium fertilization can improve the nutritional quality of food consumed by humans.

In some crops and soils, magnesium fertilization can increase tissue magnesium concentrations.

In others, the response is small or absent.

Soil magnesium and human magnesium intake

A plausible chain exists:

Soil magnesium → plant magnesium → dietary magnesium → human magnesium status.

But each step is influenced by additional variables.

For example, refining wheat removes much of its magnesium-rich bran and germ.

Consequently, food processing can substantially reduce magnesium intake even when the original wheat was grown in magnesium-sufficient soil.

PMC research:
Magnesium in Human Health and Disease

PART XI. MYCORRHIZAE: THE UNDERGROUND PARTNERSHIP

17. The Biological Network Beneath the Soil

One of the most fascinating discoveries in soil science concerns mycorrhizal fungi.

The term mycorrhiza comes from Greek words referring to fungus and root.

Mycorrhizae are symbiotic relationships between fungi and plant roots.

Many terrestrial plant species participate in these relationships.

How the relationship works

Plants manufacture carbohydrates through photosynthesis.

They transfer some of these carbon compounds to their fungal partners.

The fungi extend microscopic filaments called hyphae into surrounding soil.

These filaments can explore soil spaces beyond the immediate reach of plant roots.

In exchange for plant-derived carbon, the fungi can help plants acquire nutrients and water.

Which minerals are involved?

Mycorrhizal associations are especially important for phosphorus acquisition.

Depending on the fungal species, crop, and soil conditions, they may also influence the uptake of:

Zinc.
Copper.
Nitrogen.
Sulfur.
Other mineral nutrients.

The effects on magnesium and calcium are less consistent.

Why phosphorus is particularly interesting

Phosphorus moves relatively slowly through soil.

Plant roots can rapidly deplete available phosphorus in their immediate surroundings.

Mycorrhizal hyphae extend the effective nutrient-absorbing network.

This can substantially improve phosphorus acquisition under certain conditions.

Can modern agriculture damage mycorrhizae?

Some agricultural practices can disrupt fungal networks.

These include:

Repeated intensive tillage.
Long periods without living plant roots.
Certain fungicides.
Severe soil compaction.
Loss of organic matter.

Excessive phosphorus fertilization may also reduce the plant’s investment in mycorrhizal partnerships.

However, it is incorrect to assume that all conventional farming eliminates beneficial soil fungi.

Many modern agricultural systems retain substantial microbial activity.

Reduced tillage, cover crops, diversified rotations, and appropriate nutrient management can support mycorrhizal communities.

The human-health connection

A biologically active soil can improve plant nutrient acquisition and resilience.

However, the scientific evidence directly linking greater mycorrhizal abundance to improved long-term human health outcomes remains limited.

That relationship is biologically plausible but not yet demonstrated across the entire food chain.

PMC research:
Arbuscular Mycorrhizal Fungi and Plant Mineral Nutrition

PART XII. BIODYNAMIC FARMING VERSUS CONVENTIONAL AGRICULTURE

18. What Is Biodynamic Farming?

Biodynamic agriculture originated in the 1920s through the teachings of Rudolf Steiner.

It treats the farm as an interconnected ecological system.

Practices may include:

Composting.
Crop rotation.
Animal integration.
Cover cropping.
Organic soil amendments.
Biodiversity management.
Specialized biodynamic preparations.
Agricultural activities timed according to astronomical calendars.

Many of these practices overlap with organic and regenerative agriculture.

What does the evidence show?

Research supports several soil-management practices commonly used in biodynamic systems.

Compost can improve soil structure and organic matter.

Cover crops can reduce erosion and improve nutrient cycling.

Crop rotation can help manage pests and disease.

Reduced soil disturbance can benefit soil organisms.

A more useful comparison

Rather than dividing agriculture into conventional versus biodynamic, it may be more productive to compare:

Yield-focused agriculture

with

Yield-and-nutrient-quality-focused agriculture.

The latter would optimize:

Agricultural productivity.
Soil biological health.
Mineral availability.
Food nutrient density.
Environmental sustainability.
Economic feasibility.

Modern agricultural science is increasingly capable of measuring these outcomes.

Agronomic biofortification

One promising strategy is agronomic biofortification.

This involves using fertilizer management to increase concentrations of nutrients important to human health.

Examples include:

Zinc fertilization to increase grain zinc.
Selenium fertilization to increase selenium in food crops.
Iodine biofortification in selected crops.
Iron management where soil conditions permit useful increases.

Genetic biofortification can also improve mineral accumulation or bioavailability through plant breeding.

These approaches can complement conventional fertilization rather than requiring an entirely different farming philosophy.

PMC research:
Agronomic Biofortification of Crops With Zinc and Selenium

PART XIII. THE SEVENTH YEAR: AN ANCIENT AGRICULTURAL PRINCIPLE

19. The Biblical Sabbatical Year

The Old Testament contains a remarkable agricultural instruction.

In Leviticus 25:3–4, the Israelites are instructed to cultivate their fields for six years and allow the land to rest during the seventh year.

Exodus 23:10–11 contains a related instruction.

The seventh-year rest was part of a broader religious, social, and economic system.

It included provisions for the poor and for animals.

Was this an early recognition of soil fertility?

It is tempting to interpret the sabbatical year as an ancient agricultural sustainability program.

There may indeed have been practical agricultural benefits.

Allowing land to remain uncultivated can:

Reduce continuous nutrient removal.
Permit vegetation to regenerate.
Support certain soil organisms.
Reduce some pest pressures.
Improve soil structure under appropriate conditions.

However, leaving land fallow does not automatically replenish minerals removed by previous harvests.

Mineral elements must come from somewhere.

Biological nitrogen fixation can add nitrogen to soil when suitable legumes and microorganisms are present.

But plants cannot manufacture calcium, magnesium, selenium, or zinc.

Those elements must be supplied through weathering, atmospheric deposition, irrigation water, organic amendments, or fertilizers.

An important modern distinction

Bare fallow soil may actually lose nutrients and organic matter through erosion and leaching.

A field maintained with cover crops may provide greater benefits than one left completely bare.

Thus, the ancient principle of periodically reducing agricultural pressure remains relevant, but modern soil science can improve its application.

PART XIV. PRECISION AGRICULTURE: SATELLITES, SENSORS, AND MINERAL MANAGEMENT

20. Can Farmers Measure Mineral Deficiencies From Space?

Modern precision agriculture has advanced dramatically.

Farmers increasingly use:

GPS-guided tractors.
Satellite imagery.
Drone photography.
Geographic information systems.
Soil sampling grids.
Electrical conductivity mapping.
Variable-rate fertilizer application.
Automated irrigation systems.
Computerized yield mapping.

What satellites can detect

Satellite imagery can estimate or monitor:

Vegetation vigor.
Leaf canopy development.
Chlorophyll-related characteristics.
Crop stress.
Water availability.
Certain spatial patterns associated with nutrient deficiencies.

The Normalized Difference Vegetation Index, or NDVI, is one commonly used measure.

What satellites generally cannot do

Satellites cannot directly and reliably determine the precise concentration of every essential mineral in a field simply by photographing the crop.

A pale leaf may indicate nitrogen deficiency, iron deficiency, disease, root damage, or another stressor.

Different problems can produce similar spectral patterns.

Therefore, remote sensing is most useful when combined with:

Soil testing + plant tissue analysis + geographic mapping + targeted fertilizer application.

Variable-rate fertilization

Imagine a 100-acre field.

Soil testing reveals:

One section deficient in magnesium.
Another section deficient in zinc.
Another section with excessive phosphorus.
Another section with adequate nutrient reserves.

Rather than applying identical fertilizer quantities everywhere, GPS-controlled equipment can deliver different treatments to different zones.

This can reduce waste and improve nutrient management.

The next frontier

The most interesting opportunity may be to combine precision agriculture with nutritional analysis of harvested food.

Instead of measuring success only in bushels per acre, agricultural systems could also evaluate:

Milligrams of magnesium per kilogram of grain.
Zinc concentration.
Selenium concentration.
Iron bioavailability.
Protein quality.
Phytochemical content.

This would create a more complete measure of agricultural success.

Nutrients produced per acre could become an important companion to calories produced per acre.

PART XV. NUT TREES AS MINERAL COLLECTORS

21. Are Pecans, Walnuts, and Almonds Particularly Rich in Minerals?

Nuts are among the more mineral-dense foods in the human diet.

They frequently provide substantial amounts of:

Magnesium.
Copper.
Manganese.
Zinc.
Phosphorus.
Potassium.

Mineral content of selected nuts

Approximate values per 100 grams of edible nuts:

Nut	Magnesium	Zinc	Copper	Manganese
Almonds	270 mg	3.1 mg	1.0 mg	2.2 mg
Cashews	292 mg	5.8 mg	2.2 mg	1.7 mg
Pecans	121 mg	4.5 mg	1.2 mg	4.5 mg
Walnuts	158 mg	3.1 mg	1.6 mg	3.4 mg
Brazil nuts	376 mg	4.1 mg	1.7 mg	1.2 mg
Hazelnuts	163 mg	2.5 mg	1.7 mg	6.2 mg

Values are approximate and vary by cultivar, growing conditions, and analytical source.

Why are nuts mineral-rich?

Several factors contribute.

First, nuts are seeds.

Seeds must provide nutrients for the developing embryo and early seedling.

Second, nuts have relatively low water content compared with fresh fruits.

This concentrates nutrients on a weight basis.

Third, perennial trees develop extensive root systems that can explore substantial volumes of soil.

However, it would be inaccurate to say that nut trees universally absorb more minerals than all other plants.

Their mineral content depends on the element, soil conditions, species, and physiological transport mechanisms.

The Brazil nut example

Brazil nuts provide a dramatic illustration of geographical mineral variation.

Their selenium concentration can vary enormously depending on the soil where the trees grow.

Some Brazil nuts contain enough selenium that regularly eating several can exceed recommended intake levels.

The adult tolerable upper intake level for selenium in the United States is 400 µg daily.

Therefore, Brazil nuts demonstrate both the nutritional potential and the potential hazards of mineral accumulation.

A limitation: phytate

Nuts also contain phytate, which can bind certain minerals and reduce their absorption.

This is especially relevant to zinc and iron.

Therefore, total mineral concentration is not identical to bioavailable mineral content.

Food preparation, dietary composition, and individual nutritional status all influence absorption.

PMC research:
Nuts, Minerals, and Human Health

PART XVIII. AN IMPORTANT ADDITION: MINERAL BIOAVAILABILITY IN HUMANS

24. The Soil Is Only the Beginning

Even if a plant contains substantial mineral nutrients, the human body must absorb and utilize them.

Consider zinc.

Zinc in meat is generally relatively bioavailable.

Zinc in whole grains and legumes may be less readily absorbed because of phytate.

Similarly, iron occurs in different forms.

Heme iron from animal foods is generally more readily absorbed than nonheme iron from plant foods.

Vitamin C can enhance nonheme iron absorption.

Calcium, phytate, and polyphenols can influence absorption under certain conditions.

Magnesium absorption is affected by dietary intake, intestinal physiology, and other factors.

Therefore, optimal mineral nutrition requires attention to several stages:

Soil concentration → soil availability → plant uptake → food processing → intestinal absorption → cellular utilization.

Each stage can limit the final nutritional outcome.

A useful example: whole wheat

The wheat plant may accumulate substantial magnesium and zinc.

However, refining wheat into white flour removes much of the bran and germ.

These fractions contain a considerable proportion of the grain’s minerals.

Thus, even excellent agricultural mineral management cannot compensate completely for nutrient losses during processing.

This is why a complete nutritional strategy must address both agriculture and food choices.

PART XIX. THE FUTURE: FARMING FOR HUMAN HEALTH

25. What Would an Ideal Agricultural System Look Like?

Imagine a farming system in which success was measured not only by the weight of the harvest but also by the nutritional value of the food produced.

A modern farm might monitor:

Agricultural measurement	Nutritional objective
Crop yield	Adequate food production
Soil magnesium	Support appropriate plant magnesium nutrition
Soil zinc	Improve zinc availability
Selenium in edible crops	Support adequate selenium intake
Iron concentration	Improve dietary iron supply
Soil organic matter	Support soil function
Mycorrhizal activity	Support nutrient acquisition
Soil pH	Improve nutrient availability
Food mineral analysis	Measure actual nutrient density
Contaminant testing	Minimize toxic element exposure

This would represent a shift from a purely production-centered agricultural model toward a more integrated nutritional model.

However, an important scientific distinction remains.

Increasing the mineral content of food is not necessarily beneficial if the population already receives adequate quantities of that mineral.

Selenium illustrates this perfectly.

In selenium-deficient regions, biofortification may offer important health benefits.

In selenium-sufficient regions, indiscriminate enrichment could create unnecessary exposure.

The same principle applies to iodine, copper, manganese, and other trace elements.

The objective should be to correct meaningful nutritional inadequacies rather than simply maximize elemental concentrations.

MINERALS AND LIFE EXTENSION

Since the dawn of time, glaciers have become giant pieces of sandpaper on nearby rocks and mountains. Grinding away at mountains to produce fine powders of minerals. There is intriguing evidence that people who drink the water from this glacial abrasion have a longer life.

The Hunza people living in the mountains of Pakistan, the Vilcabamba group in Ecuador Andes mountains of South America, the Abkhazia in the Caucasus mountains of Russia all exhibit extraordinary health and lifespan. All consume glacial milk water and use that water for their crops.

While modern science labors into the wee hours in pursuit of cures for disease and aging, maybe one solution is to provide humans with optimal intake of essential minerals. On a risk to benefit to cost ratio, there are no better options out there.

PART XX. SCIENTIFIC RESEARCH AND FURTHER READING

The following research topics provide a useful foundation for further investigation through the National Library of Medicine’s PubMed Central database.

Subject	Research resource
Historical changes in food mineral composition	Davis et al., 2004
Magnesium and human health	Magnesium in Human Health and Disease
Boron and human physiology	Nothing Boring About Boron
Selenium and Keshan disease	PMC Research Collection
Copper deficiency and swayback	PMC Research Collection
Cobalt deficiency in grazing animals	PMC Research Collection
Soil mineral availability and pH	PMC Research Collection
Mycorrhizae and nutrient uptake	PMC Research Collection
Agronomic biofortification	PMC Research Collection
Organic versus conventional nutrient composition	PMC Research Collection
Precision agriculture and nutrient management	PMC Research Collection
Soil microbiome and plant health	PMC Research Collection

PART XXI. TEN IMPORTANT CONCLUSIONS

1. Human mineral nutrition begins with geology.

The mineral composition of soil and water influences the mineral content of the food chain.

2. Plants and humans do not require identical minerals.

Selenium and iodine demonstrate why a crop can grow normally while providing insufficient amounts of nutrients essential to human health.

3. Agricultural yield and nutritional quality are related but distinct objectives.

A larger harvest does not necessarily provide proportionally more minerals.

4. Soil pH is a critical determinant of nutrient availability.

Adding minerals without considering soil chemistry can be ineffective or counterproductive.

5. Soil microorganisms are essential partners in nutrient cycling.

Mycorrhizal fungi can improve the acquisition of certain nutrients, particularly phosphorus.

6. Mineral deficiencies can produce geographically concentrated diseases.

Keshan disease and livestock disorders associated with copper and cobalt deficiencies illustrate this relationship.

7. Magnesium deserves greater nutritional attention.

Many Americans consume less magnesium than recommended, although the causes include food selection and processing as well as agricultural factors.

8. Nuts are valuable dietary sources of minerals.

Their mineral content reflects seed biology, low moisture content, plant genetics, and environmental conditions.

9. Precision agriculture offers a promising opportunity.

Soil testing, tissue analysis, remote sensing, and variable-rate fertilization can support more targeted nutrient management.

10. Soil remineralization should be guided by measurement rather than assumption.

Excess minerals can be as undesirable as deficiencies.

FINAL PERSPECTIVE: THE HEALTH OF THE SOIL AND THE HEALTH OF HUMANITY

There is a compelling continuity between the mineral chemistry of the Earth and the mineral chemistry of the human body.

The magnesium atom participating in an ATP-dependent reaction within a human cell may once have been part of a rock.

Weathering released that magnesium into the soil.

A plant absorbed it through its roots.

An animal or human consumed the plant.

The mineral eventually became part of living biochemistry.

This is not metaphor.

It is the literal movement of matter through the biosphere.

Yet the relationship is more complicated than simply adding minerals to soil.

Healthy agriculture requires appropriate soil chemistry, biological activity, water management, plant genetics, and mineral balance.

Healthy human nutrition requires adequate food intake, mineral bioavailability, normal absorption, and physiological regulation.

The scientific opportunity lies in connecting these disciplines.

For much of modern agricultural history, the dominant question has been:

How much food can we produce from an acre of land?

An increasingly important companion question is:

How much useful nutrition can we produce from that same acre?

Those questions need not compete.

Indeed, the most successful agricultural systems of the future may be those capable of answering both.

A final thought

The ground beneath our feet is not merely a physical platform upon which plants grow.

It is a dynamic chemical and biological environment that helps sustain the food chain.

And while nourishing the soil does not automatically guarantee human health, neglecting soil fertility can undermine the nutritional quality and long-term sustainability of our food supply.

Perhaps the future of preventive nutrition should begin not only in the kitchen, the grocery store, or the physician’s office, but also in the soil laboratory and on the farm.

That is a proposition worthy of serious scientific investigation.