The latest news on the nutritional merry-go-round: it’s complicated

I’m making egg salad sandwiches for a reception for my friend Lyn’s book reading today. Her book, a memoir, is called “God is not a boy’s name: becoming woman, becoming priest”.  Check it out.

It’s been awhile since I’ve hard-boiled a dozen eggs, so I decided to google the best way to do this—put eggs in before boiling water, boil water first, what?

And what do I find out? Sources don’t agree about this—some say do this, some say do that. They all claim that their way is the best method for getting the perfect hard-boiled egg.

Since all I need here is fully cooked eggs for mashing and making egg salad (with pickle, of course), it does matter very much HOW I cook them; as long as they’re fully cooked at the end, everything will be fine.

However, when it comes to nutritional advice, the stakes seem considerably higher. What we really want is some clarity about how to eat in ways that are healthy (to us) and reduce risks for conditions like diabetes and heart disease.. In the blog we’ve tackled this issue a lot—check it out here and here and here, for instance.

Still, shouldn’t SOMETHING be clear by now? Well, to paraphrase Oprah, it seems like one thing we know for sure is this: diets high in unsaturated fats (like vegetable oils and some fish) are much healthier for your heart than diets high in saturated fats (like animal fats in meats, butter, cheeses). Why? Because a diet emphasizing unsaturated fats lowers your serum cholesterol and reduces your risk of cardiovascular disease. Right?

 

maybe not

 

The latest episode in the “what in the world should I eat to be healthy?” saga has an interesting, sort of mysterious twist (relative to nutrition research, which has a low bar for what counts as mysterious). The Minnesota Coronary Experiment, done from 1968 to 1973, controlled and studied the diets of more than 9500 people living in nursing homes and mental hospitals. But—and here’s the twist—the data were not analyzed. Until now…

You can read the interesting backstory here, but the upshot is that the data were just recently found, analyzed and published here. And the results are surprising; here’s an excerpt from the Well blog story:

The results were a surprise. Participants who ate a diet low in saturated fat and enriched with corn oil reduced their cholesterol by an average of 14 percent, compared with a change of just 1 percent in the control group. But the low-saturated fat diet did not reduce mortality. In fact, the study found that the greater the drop in cholesterol, the higher the risk of death during the trial.

The findings run counter to conventional dietary recommendations that advise a diet low in saturated fat to decrease heart risk. Current dietary guidelines call for Americans to replace saturated fat, which tends to raise cholesterol, with vegetable oils and other polyunsaturated fats, which lower cholesterol.

Now that’s a surprise. It turns out that the low-saturated fat diets lowered serum cholesterol but didn’t lower mortality risks—rather the greater drop in cholesterol was associated with a higher mortality risk. How could this be? The researchers have a hypothesis:

One explanation for the surprise finding may be omega-6 fatty acids, which are found in high levels in corn, soybean, cottonseed and sunflower oils. While leading nutrition experts point to ample evidence that cooking with these vegetable oils instead of butter improves cholesterol and prevents heart disease, others argue that high levels of omega-6 can simultaneously promote inflammation. This inflammation could outweigh the benefits of cholesterol reduction, they say.

And there’s more data from other studies to support this unexpected result.

In 2013, Dr. Ramsden and his colleagues published a controversial paper about a large clinical trial that had been carried out in Australia in the 1960s but had never been fully analyzed. The trial found that men who replaced saturated fat with omega-6-rich polyunsaturated fats lowered their cholesterol. But they were also more likely to die from a heart attack than a control group of men who ate more saturated fat.

If you look at the original paper, published in the British Medical Journal, it has an extended explanation and some hypothesizing about the role of lineolic acid (vegetable oils are rich in this, unlike animal fats) in biochemical processes that contribute to heart disease.

But at the very end of the article, it uses a word I’ve never read in a medical journal:

Given the limitations of current evidence, the best approach might be one of humility, highlighting limitations of current knowledge and setting a high bar for advising intakes beyond what can be provided by natural diets.

Humility is the word.

 

humility

 

The researchers are acknowledging the complex nature of human metabolic interactions in our current industrial food system, suggesting ways to proceed scientifically with more rigor than we previously have, and offering up humility and modesty as appropriate attitudes for any approach to dietary advice.

In the current maelstrom of competing theories for how to fill my plate, this is advice I can take to heart.

About catherine w

I'm an analytic philosopher, retooled as a public health ethicist. I'm interested in heath behavior change, particularly around eating and activity, and how things other than knowledge affect our health decisions.I'm also a cyclist (road, off-road, commuter), squash player, x skier, occasional yoga-doer, hiker, swimmer and leisurely walker.

2 thoughts on “The latest news on the nutritional merry-go-round: it’s complicated

  1. Jean says:

    This looks like a good blog. She is a registered dietician + did have a history of weight loss problems. She talks about attitude now, etc.
    https://daretonotdiet.wordpress.com/

    This post talks about competent eating https://daretonotdiet.wordpress.com/2016/04/18/food-is-not-medicine/ I like that because the focus is on nutritious varied and balanced meals. Not overfocus on 1 nutrient or 1 food.

    My only comment about butter is that there are whole cultural cuisines that never had butter nor hardly any dairy in the traditional cuisine at all. Think about the 2,000 year old Chinese cuisines….its gastronomy rivals French culinary history..very complex, incredible techniques both easy and chef-like, multiple regional variations..yet probably only 20% of the cuisine has any dairy stuff. That would be the cuisine of northern China where they have goats, cows for milking.
    Cheese, milk, butter and yogurt was very foreign to my parents when they immigrated to Canada in the 1950’s. They were from the hot, tropical southern China…where a lot of the Chinese immigrants came from to North America from 1800’s to mid 1900’s.

    Liked by 1 person

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