Thursday, 18 July 2019 08:55

Beware of research taken out of context

Written by  Dr Jacqueline Rowarth
Jacqueline Rowarth. Jacqueline Rowarth.

OPINION: A misreported study from Denmark could spoil New Zealand’s reputation, or create health worries which are unfounded.

Alarm bells have been sounded about wells on the Canterbury Plains: the water might be undrinkable in 100 years because of nitrate. 

The problem has been explained as one of colorectal cancer, based on a study in Denmark. Colorectal cancer is known to be linked to obesity, processed meat, red meat and alcohol. 

Contrary to newspaper reports, the Danish study was not able to take lifestyle factors, including diet, into account. This was pointed out in a subsequent review by American scientists which advised more research before links could be made. 

Reassuringly, other research has shown no link between dietary intake of nitrate and colorectal cancer. There might even be a protective effect because of associated antioxidants (hence beetroot and kale are considered ‘super-foods’).

The issue of increasing nitrate in well water remains, and is being taken seriously by farmers, scientists and industry. Their efforts might be having an effect. The Environment Canterbury Survey in spring 2018 reported a reduction from 10% in 2017 to 7% in the number of wells with higher than recommended nitrate. Of course winter rainfall and summer drought affect nitrate release and movement in the soil, but each year more is being done on farm to reduce nitrate loss, backed by science.

Last year, Ecotain, the plantain selection shown to reduce nitrogen loss in various ways, won the National Fieldays Innovation Award. Ecotain was developed by Agricom and has been tested independently by Lincoln and Massey Universities and DairyNZ. It is now in pastures NZ-wide and evaluation in on farm trials is continuing. 

This year, Cleartech, a system for reducing the nutrient concentration in dairy shed effluent, was highly commended in the Innovation Awards. Cleartech is a development between Lincoln University soil scientists and Ravensdown. 

As more research is completed and technologies developed, farmers are adopting new practices and the results are becoming apparent. The LAWA reports on water quality indicate that an increasing number of rivers are improving in all parameters, including nitrate.

Our Fresh Water, published in 2017 by The Ministry for the Environment stated that “more than 99% of total river length was estimated not to have nitrate-nitrogen concentrations high enough to affect the growth of multiple sensitive freshwater species for the period 2009–13”. And LAWA has reported improvements since then. Concentrating on the rivers with a problem would seem to make sense. 

The same applies to the issue of cancer. The Ministry of Health reported this year that in 2017 there were 3081 cases of colorectal cancer registered, 3294 of breast cancer and 3834 of prostate cancer. There were also 2226 registered cases of lung cancer and 2552 of melanoma. Incidences of other types of cancers numbered below 1000 each. 

The World Cancer Research Fund is active in trying to assist people to understand how to avoid cancer: don’t smoke, avoid cigarette smoke, be as lean as possible within the healthy weight range, be physically active, avoid foods and drinks that promote weight gain, eat plants, limit intake of red meat, avoid processed meat and limit alcohol consumption.

Sadly, doing everything recommended is no guarantee that cancer will stay away. Genetics are involved and ‘adult attained height’ is a marker for cancer still being investigated.

More research is always required. Problems are revealed, scientists investigate using ever more advanced techniques, and ideas with potential are tested then developed. Innovative farmers, many of whom are involved in the research process, adopt the new technologies, showing the way for the future. 

People from other countries come to New Zealand to see how we operate. They admire the farming as well as the environment, and enjoy the food we produce. 

It would be a pity if a misreported study from overseas spoiled New Zealand’s reputation, or created health worries which are unfounded.

• Dr Jacqueline Rowarth CNZM CRSNZ HFNZIAHS is a soil scientist. 

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