Busting a nutrient myth

Differences in nutrient concentration are to do with soil and climate (terroir), stage of harvesting and cultivar or breed, not production methods. By Jacqueline Rowarth.

Repeated statements of a falsehood does not make the falsehood true. Yet these days it appears the more something is said (or repeated on social media), the more people seem to believe it.  Lewis Carrol termed the phenomenon the Snark Syndrome. In The Hunting of the Snark, the Bellman says “What I tell you three times is true”. 

In psychology, it’s termed the illusory truth effect – the tendency to believe false information after repeated exposure. You start to believe it because ‘everybody knows’. 

We see the effect in people reluctant to be vaccinated with the most tested vaccine in history.

We see it in pushback against agrichemicals that are enabling people to have access to affordable food supply. 

We see it in the nutrient density myth – modern agriculture is robbing you of the healthy food you deserve.

And now there is a research programme that is apparently going to show that food grown regeneratively is tastier and healthier for people than conventionally produced food. The programme will show that regeneratively produced will have greater nutrient density – the amount of a particular nutrient in a food per calorie or kilojoule consumed.

Note that science does not generally ‘set out to prove’, instead it tests hypotheses, thereby retaining an open mind.

As science has not managed to prove any consistent differences in food produced in different farming systems in the past, it is unclear why anybody would think throwing more money at the non-issue will do so in the future.

Repeated meta-analyses and reviews can find no credible research showing that nutrient concentration in food produced organically or conventionally differs substantively. The same goes for modern food compared with 50 years ago. The occasional small difference is nothing in context with the full diet.

Differences in nutrient concentration are to do with soil and climate (terroir), stage of harvesting and cultivar or breed. There are also some differences between now and the past due to increased carbon dioxide concentration in the atmosphere – but there aren’t differences between organic and conventional grown in the same year in the same soil. 

Why would results differ?

Given that regenerative agriculture is part of the spectrum between organic and conventional, along with agro-ecology and conservation agriculture, why would the results be different?

Note that the ‘no difference’ is before the farm, orchard or market garden gate.

Food grown at home tastes better than the alternative because it is fresher – you harvest it at its best and eat it immediately. But the home gardener mostly cannot provide the variety of fruit and vegetables available all year round from the supermarket.

Once the food leaves the producer, and goes to the processor and distributor, things change.

Post-harvest treatment is critical. Snap-frozen peas frequently have more sweetness than fresh peas (unless grown at home) because they are harvested at the peak of perfection, frozen within a four-hour window of harvest, and the transport and waiting to be bought occurs when the peas are already preserved.

Processing often adds components to the original product and dilutes the ‘nutrient density’. Potatoes contain a considerable number of nutrients. Deep-fried and salted the value reduces. The same goes for oats turned into muesli bars with fat and sugar.

The debate about milk and meat is slightly different. Within a species, breed does make a difference. Milk from Jersey cows is higher in fat than that from Holstein Friesians. Processors in New Zealand collect the milk and blend it to ensure a consistent quality, then meet consumer demand with low fat, high calcium, chocolate…. 

This is nothing to do with the production system of the farmer or grower but does change nutrient density.

Similarly, many differences have been recorded in meat from pasture-fed animals in comparison with grain-fed. In particular, the omega 3s are higher (up to five times) in grass-fed meat, just as they are in grass-fed milk. If, however, you are deficient in omega 3s, switching to ‘grass-fed’ won’t make much difference to your health (particularly in NZ where the norm is pasture) – you will need supplements. 

The suggestion that slower growing leads to better-tasting meat may well be the case overseas where hormones are given to animals to increase growth rates. In NZ they are not given additional hormones; they respond to their own hormones and genetic potential, reaching weight according to food quality and quantity. 

On pasture, if animals grow slowly the implication is that there is something wrong, perhaps health or food restriction (quantity and/or quality). 

More greenhouse gases

The environmental concern is that greenhouse gases (GHG) produced per kilogram of food are increased in slow-growing animals because of the extra time taken to reach weight and the maintenance costs.

GHGs are an important factor when suggesting that organics, regenerative or whatever are ‘kinder’ to the environment than conventional systems. Considerable research has shown that per unit of food produced, conventional agriculture has lower impact on the environment than any other system because yields are higher per unit of input.
The converse is that yields are lower per hectare with regenerative or organic farming in comparison with conventional farming which means more land is required to feed a given population. Deforestation is the consequence.

What drives food demand is mouths and there are more and more of them on the planet.

NZ food is in demand because it is high quality and is produced with lower environmental impact than most other countries can manage. 

What happens to the raw product before it reaches the consumer is a matter of consumer choice. Make the decision to purchase unprocessed food and nutrient density will be as high as in the past.

The illusory truth effect is allowing people to blame poor nutrient density on farming practices rather than their personal food choices. It is also encouraging the belief that a return to past production systems will cure everything. Success would require a return to past population as well.

• Dr Jacqueline Rowarth, adjunct Professor Lincoln University, is a farmer-elected Director of DairyNZ and Ravensdown. The analysis and conclusions are her own. jsrowarth@gmail.com