Our food is losing nutrients

Our grandmothers were right. Our vegetables—and not just the tomatoes (called "Paradeiser" here in Austria)—really don't taste like 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 types of vegetables and 17 types of fruit from 1940 with those from 1991. The result was alarming: the magnesium content in vegetables had dropped by almost 25 percent. Calcium by 46 percent. Sodium by 50 percent. Copper by more than 75 percent.
Research from the University of Texas arrived at a similar conclusion: between 1950 and 1999, the content of vitamins and minerals in fruit and vegetables decreased by up to 40 percent.

In other words, we have to eat significantly more today to get the same amount of nutrients our grandparents absorbed from 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 were the first to prove what is now known as the dilution effect: the higher the yield of a plant, 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 actually benefits us as humans.

Depleted soils. Intensive agriculture drains minerals from the soil year after year—without sufficient replenishment. What is missing in the soil, the plant cannot absorb. And what the plant does not absorb is missing from our plate.

Early harvesting and long transport routes. A tomato harvested unripe that ends up in a supermarket after a week of transport has never had the chance to fully develop its nutrients. Ripening happens in the field—not in a truck.
Biochemist Donald Davis from the University of Texas summarized it this way: people in Western societies are starving despite being overweight. Their energy intake is secured—but they are lacking 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 only 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 keeps you full for longer.

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

The Brix value: The simplest quality indicator

The Brix value (°Brix) measures the density of plant sap—originally developed to determine sugar content, it is now 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. American agronomist Dr. Carey Reams recognized as early as the mid-20th century: 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 onto which you place a few drops of plant sap. The device measures the light refraction of the sap and displays the Brix value in seconds.

What are good values?

A conventionally grown supermarket tomato today is often at 4–5 °Brix. A tomato from healthy soil and natural cultivation can reach 10–12 °Brix—that is 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 in a plant, density means: fullness. Vitality. Substance.

Who actually tests the nutrient density of our food?

Here lies a systemic problem that almost no one knows about.

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

But what do these institutions test for?

Mainly for safety—pesticides, heavy metals, germs, allergens, residues. Things that should not be in there.
No one systematically tests for what should be in there. No one checks the mineral density at the producer level. No one compares whether a carrot from region A contains more calcium than one from region B.
The consumer organization Stiftung Warentest tests food selectively—but also mainly for pollutants and accuracy of labeling.

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

Photosynthesis is the key—and calcium is the door opener

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

What does a plant need for optimal photosynthesis?

Light, water—and CO₂ in sufficient quantity directly at the site of photosynthesis, in the leaf.

Here, calcium plays a decisive 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, and lower nutrient density.
Calcium is also essential for the stability of cell walls, the uptake of nitrogen, resistance to disease, and the quality of the fruits. 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 a higher Brix value.

What happens when you do it right—real-world data

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 for themselves:

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

Lettuce (Cundinamarca, 2017): 16.8 percent more growth, harvest time shortened by 7 days. This is good because it allows farmers to deliver more quickly.

Broccoli (Cundinamarca, 2017): 65 percent higher growth rate, 7 days earlier harvest, significantly higher biomass. It is extremely gratifying to see broccoli respond 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 maturity in the field means more time for nutrient accumulation.

This is directly reflected in the Brix value—and therefore on our plates. And in the cells of our bodies.

What this means for us as consumers

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

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

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

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

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

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

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 handheld refractometer — such as the Anton Paar SmartRef (an Austrian device, measuring range 0–85 °Brix, result in 2 seconds) or the proven ATAGO PAL-1 — is available for around 250–350 euros and provides you with information about the quality of your harvest in seconds.

 

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

The result is measurable. In weeks, not years.

Sources: British Government, Mineral comparison of 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 you can grow nutrient-dense carrots.
We also have a guide for nutrient-dense strawberries.
And one for nutrient-dense garlic.
And now also one for nutrient-dense tomatoes.

 

Also for nutrient-dense Hokkaido pumpkin.

 

Everything about Brix measurements