CORRELATION IS NOT CAUSATION

The ABC republishes a piece from The Conversation by Dr Alessandro Demaio, classifying his opinions as analysis.

The most compelling reason to eat healthy foods is the correlation between good nutrition and wellbeing.

Coupled with regular exercise, eating a diet rich in whole foods and grains, healthy oils and low in sugar and salt, has been shown to convey a number of benefits.

These include a longer life with less pain and suffering, less risk of back pain or muscular problems and even an increased libido.

Studies from around the world also show people with healthy diets are less likely to experience depression while unhealthy diets may put individuals at an increased risk of depression.

The actual premise of the linked “less pain and suffering” – no mention of “whole foods and grains” and “healthy oils” –  study:

Healthy lifestyles based on non-smoking, an acceptable BMI, a high fruit and vegetable intake, regular physical activity, and low/moderate alcohol intake, are associated with reductions in the incidence of certain chronic diseases, but to date there is limited evidence on cognitive function and dementia.

The “less likely to experience depression” link notes a possibility of reverse causation. That is, that depressed persons might be inclined to have “unhealthy diets”.

It’s the same for the linked “increased risk of depression” study, which notes:

There are several limitations to our study. First, reverse causation – with depression affecting the dietary pattern rather than the other way around – remains an alternative interpretation of the observed associations.

Undaunted by the actual research, Dr Demaio continues:

Recent research has also reconfirmed a link between bowel cancer and red meat consumption. Processed meats such as ham, bacon and salami appear to be especially problematic.

The cited research is, however, suggestive rather than conclusive, listing processed meats – which are rich in additives – as a “convincing” cause of cancer while including red meat as a “probable” cancer cause. Interestingly, Demaio fails to note that the much maligned high-in-fat dairy products are deemed protective:

Consuming dairy products decreases the risk of colorectal cancer.

Demaio’s health concerns are actually secondary to his primary agenda:

It might surprise you, but 30% of Global Greenhouse Gasses come from what we eat – from food production. And a vast amount of this is generated by a small portion of our plate: meat. In fact, beef and lamb are by far the worst at soiling the global and local environments. Each kilogram uses 15,500 litres of water to produce and creates 30-40 kg of carbon dioxide (the same as driving 60-90 miles). Grazing occupies 26% of the earth’s ice-free land, and feed crop production uses about one third of all arable areas.

The key take-aways for a longer life: don’t smoke; avoid alcohol; don’t overeat; and consume a varied diet. It’s common sense, really.

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