Our food is losing nutrients

Our grandmothers were right. Our vegetables, not just tomatoes, really don't taste the way they used to. And that's not nostalgia — that's science.

A long-term study by the British government compared the mineral content of 27 vegetable varieties and 17 fruit varieties from 1940 with those from 1991. The result was alarming: the magnesium content in vegetables had decreased by almost 25 percent. Calcium by 46 percent. Sodium by 50 percent. Copper by more than 75 percent.
A study by the University of Texas came to a similar conclusion: Between 1950 and 1999, the content of vitamins and minerals in fruits and vegetables decreased by up to 40 percent.

This means that we have to eat significantly more today to get the same amount of nutrients that our grandparents absorbed with a single portion.

Why is this happening — and who is to blame?

The answer is uncomfortable because it concerns our entire food system.

The dilution effect. In the 1980s, researchers Jarrell and Beverly first demonstrated what is now known as the dilution effect: the higher a plant's yield, the lower its nutrient density. The plant grows faster than it can absorb minerals. The result: larger, heavier, but emptier fruits and vegetables.

For decades, plant varieties have been optimized for one thing — yield. Size. Appearance. Shelf life for long transport routes. Not for taste. Not for nutrient density. Not for what really benefits us humans.

Depleted soils. Intensive agriculture depletes the soil of minerals year after year — without adequate replenishment. What is missing in the soil cannot be absorbed by the plant. What the plant does not absorb is missing on our plate.

Premature harvesting and long transport routes. A tomato that is harvested unripe and ends up in the supermarket after a week of transport never had the chance to fully develop its nutrients. Ripeness develops in the field — not in the truck.

Biochemist Donald Davis from the University of Texas summarized it as follows: People in Western societies are starving despite being overweight. The energy supply is secured — but there is a lack of micronutrients.

What nutrient density really means

Nutrient density is not a buzzword. It is the crucial difference between food that truly nourishes us and food that merely fills our stomachs.

A nutrient-dense carrot contains more calcium, more potassium, more beta-carotene, more polyphenols — and it tastes more intense, lasts longer, and is more satiating.

But how do you measure that? This is where a fascinating, centuries-old tool comes into play — the Brix value.

 

The Brix value: The simplest quality characteristic

The Brix value (°Brix) measures the density of plant sap — originally developed to determine sugar content, today it is much more than that.

A high Brix value means that the plant sap contains many dissolved substances — sugar, but also minerals, amino acids, proteins, and vitamins. The American agronomist Dr. Carey Reams recognized as early as the mid-20th century that plants with a high Brix value are healthier, more resistant to diseases and pests, taste better, and nourish humans more comprehensively.

How is it measured? With a refractometer — a handy device on which a few drops of plant sap are placed. The device measures the refraction of light of the sap and displays the Brix value in seconds.

What are good values?

A conventionally grown supermarket tomato today often measures 4–5 °Brix. A tomato from healthy soil and natural cultivation can reach 10–12 °Brix — that's double the nutrient density, double the flavor.

An important nuance: The Brix value is not just a sugar meter. It is a density meter. And density in a plant means: fullness. Vitality. Substance.

 

Who actually tests the nutrient density of our food?

Here lies a systemic problem that hardly anyone knows about.

In Austria, the AGES (Agency for Health and Food Safety) examines around 30,000 food samples annually. In Germany, the CVUAs (Chemical and Veterinary Investigation Offices) take on this task, supplemented by private laboratories such as Eurofins or AGROLAB.

But what do these institutions test for?

Mainly for safety — pesticides, heavy metals, germs, allergens, residues. What shouldn't be in there.
No one systematically tests what should be in there. No one controls the mineral density at the producer level. No one compares whether carrots from Region A contain more calcium than those from Region B.
Stiftung Warentest tests food selectively — but also mainly for harmful substances and labeling accuracy.

This means that as consumers, we have no reliable way of knowing how nutrient-rich our vegetables truly are. Unless we measure it ourselves.

Photosynthesis is the key — and calcium the opener

Why do some plants contain more nutrients than others? The answer lies in photosynthesis.
The more intensively a plant undergoes photosynthesis, the more sugar it produces — and the more minerals, amino acids, and secondary plant compounds it builds up. The Brix value increases. The nutrient density increases.

What does the plant need for optimal photosynthesis?

Light, water — and sufficient CO₂ directly to the site of photosynthesis, into the leaf.

Here, calcium plays a crucial and often underestimated role. Calcium regulates the opening and closing of the leaf pores (stomata) — through which CO₂ enters the leaf. Calcium deficiency means poorer pore regulation, less CO₂ uptake, weaker photosynthesis, lower nutrient density.
Calcium is also essential for the stability of cell walls, nitrogen uptake, resistance to diseases, and fruit quality. A plant well supplied with calcium builds thicker, more stable cells — this is visible in the more intense green of the leaves, and measurable in the higher Brix value.

What happens when you do it right — practical numbers

UMID Colombia S.A.S., an Austrian-Colombian company for agricultural technology transfer, conducted extensive field studies in 2017 and 2018 using mineral foliar fertilizers based on tribomechanically activated calcite. The results speak a clear language:

Onion (Valle del Cauca, 2018): After four applications, the treated onions weighed an average of 125 grams instead of 71 grams — a weight gain of 44.8 percent. One kilogram of the treated onions contained only 8 pieces instead of 14.5. For the farmer, this meant an economic gain of 60 percent.

Lettuce (Cundinamarca, 2017): 16.8 percent more growth, harvesting time shortened by 7 days. This is good, because then farmers can resupply faster.

 

 

Broccoli (Cundinamarca, 2017): 65 percent higher growth rate, 7 days earlier harvest, significantly higher biomass. It's great to see that broccoli responds so well to foliar fertilization.

Coffee (Cundinamarca & Cauca, 2017–2018): In the growth phase, cultivation with foliar fertilization showed 64 percent higher plant growth. In the production phase, a yield increase of 25 percent was achieved with only four applications.

Passion Fruit (Valle del Cauca, 2018): 18.1 percent more leaf density, better leaf structure and color intensity, higher plant robustness.

What these numbers mean: Not just more yield. But more substance. More intense color means more chlorophyll. Larger cells mean more calcium and water in the cell structure. Earlier ripeness in the field means more time for nutrient accumulation.

This is directly reflected in the Brix value — and thus on the plate. And in our body's cells.

What this means for us as consumers

We cannot control how our vegetables are grown. But we can make informed decisions.

Buy regional and seasonal. Short transport routes mean more time for natural ripeness in the field. A tomato that comes from a local farmer in August has more nutrients than one that was flown in from Spain in February.

Buy from farmers who take soil health seriously. Regenerative agriculture, organic farming, targeted mineral buildup in the soil — these are the practices that promote nutrient density.

Ask about the Brix value. Sounds unusual — but it will change. More and more farmers are measuring the quality of their harvest with a refractometer. Ask your farmer's market vendor. The answer says a lot. Or measure it yourself. (Today I bought two types of tomatoes, one organic quality and one conventional, because I'm always curious and want to calibrate my intuition.)

Trust your palate. Intense color, firm bite, strong taste — these are visible signs of nutrient density. The tomato that really tastes like a tomato is usually the more nutrient-rich one.

What this means for you as a farmer – what does this mean in practice for us gardeners?

The good news: nutrient density is not a coincidence. It is the result of targeted soil management and plant nutrition.

The first step is measurement. If you don't know your Brix value, you can't improve it. A digital hand refractometer — such as the Anton Paar SmartRef (Austrian device, measuring range 0–85 °Brix, results in 2 seconds) or the proven ATAGO PAL-1 — is available for around 250–350 Euros and provides information on the quality of your harvest in seconds.

 

 

 

The second step is to supply the plant precisely with what it needs — in a form it can absorb. Calcium, supplied directly to the leaf as a fine spray, works immediately. It penetrates through the leaf pores, releases CO₂ for photosynthesis, and provides calcium for cell development — without the detour through the soil. You can read exactly how Grünkraft Calcium works in this article. And in this article, how to use calcite foliar fertilizer.

The result is measurable. In weeks, not years.

Sources: British Government, Mineral Comparison Vegetables 1940/1991 | University of Texas, Donald Davis et al., 2004 | Jarrell & Beverly, Dilution Effect, 1981 | UMID Colombia S.A.S., Field Studies 2017–2018 | Dr. Carey Reams, Brix Chart for Agriculture

Read more:
Do you know the nutrients in red onions? 
And the nutrients in carrots?
Here is a guide on how to grow nutrient-rich carrots.
We also have a guide for nutrient-rich strawberries.
And one for nutrient-rich garlic.
And now also for nutrient-rich tomatoes.

 

Everything about Brix measurements