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The whole and its parts

According to NPR’s Allison Aubrey,

The reason we're told to limit dairy fat seems pretty straightforward. The extra calories packed into the fat are bad for our waistlines — that's the assumption.

But what if dairy fat isn't the dietary demon we've been led to believe it is? New research suggests we may want to look anew.

In one study published by Swedish researchers in the Scandinavian Journal of Primary Health Care, middle-aged men who consumed high-fat milk, butter and cream were significantly less likely to become obese over a period of 12 years compared with men who never or rarely ate high-fat dairy.

Yep, that's right. The butter and whole-milk eaters did better at keeping the pounds off.

The study itself “followed a cohort of rural men over 12 years” because “In a previous study we found that daily intake of fruit and vegetables in combination with a high dairy fat intake was associated with a lower risk of coronary heart disease”:

1782 men (farmers and non-farmers) aged 40–60 years at baseline participated in a baseline survey (participation rate 76%) and 1589 men participated at the follow-up. 116 men with central obesity at baseline were excluded from the analyses.

Central obesity was defined as waist hip ratio ≥ 1. Waist and hip measurements were taken at both surveys with a tape measure at the level of the umbilicus and at the widest part of the hips with the participants dressed in light wear.

The conclusion drawn is

We found that a low intake of dairy fat was associated with a higher risk of developing central obesity and that a high intake of dairy fat was associated with a lower risk of central obesity among men without central obesity at baseline. The majority of the participants were overweight or obese as defined by BMI at baseline. However, the associations between dairy fat intake and central obesity were consistent across BMI categories at baseline.

The table below indicates that regardless of which model is used, on average, high fat participants have a < 1 waist hip ratio while on average, low fat participants have > 1 waist hip ratio. Table III.

Low (no butter and low fat milk and seldom/never whipping cream)	Dairy fat intake		row 1, cell 3
Medium (all other combinations of spread, milk, and whipping cream)	row 2, cell 2	row 1, cell 3	row 1, cell 3
High (butter and high fat milk and whipping cream daily or several times a week)	row 2, cell 2	row 1, cell 3	row 1, cell 3

Risk of central obesity (waist hip ratio ≥ 1) at follow-up according to dairy fat intake at baseline. Only men with waist hip ratio < 1 at baseline were included. Dairy fat intake Crude (n = 1,303) Model 11 (n = 1,285) Model 22 (n = 1,261) OR3 95% CI OR3 95% CI OR3 95% CI Low (no butter and low fat milk and seldom/never whipping cream) 1.40 0.97–2.03 1.45 0.99–2.11 1.53 1.05–2.24 Medium (all other combinations of spread, milk, and whipping cream) 1 1 1 High (butter and high fat milk and whipping cream daily or several times a week) 0.53 0.34–0.83 0.50 0.31–0.80 0.52 0.33–0.83 1Adjusted for fruit and vegetables daily, smoking, alcohol consumption, and physical activity. 2Adjusted as above plus age, education, and profession. 3Odds ratio with 95% confidence intervals.

Discussion

1. This Swedish study is clearly not a randomized clinical trial and depends in some manner on self reporting. Why is this a problem? Why is any inference to a larger population also a problem?

2. This Swedish study has males only included. How does this limit any inference?

3. “Cheese and yoghurt for example were not included/not asked about, nor the vast list of processed dairy products available in the supermarkets of today.” What effect if any might there be because of the exclusion of cheese, yoghurt and other processed dairy products?

4. According to Aurbrey, there exists a second study, published in the European Journal of Nutrition, which

is a meta-analysis of 16 observational studies. There has been a hypothesis that high-fat dairy foods contribute to obesity and heart disease risk, but the reviewers concluded that the evidence does not support this hypothesis. In fact, the reviewers found that in most of the studies, high-fat dairy was associated with a lower risk of obesity.

"We continue to see more and more data coming out [finding that] consumption of whole-milk dairy products is associated with reduced body fat," says the executive vice president of the National Dairy Council.

Aubrey suggests “the satiety factor. The higher levels of fat in whole milk products may make us feel fuller, faster. And as a result, the thinking goes, we may end up eating less.” She further adds

As we reported last year, a study of children published in the Archives Of Diseases in Childhood, a sister publication of the British Medical Journal, concluded that low-fat milk was associated with more weight gain over time.

5. Consider “the satiety factor”--full fat keeps us lean--mentioned above. What sort of analogy might there be to gun ownership and safety? Excellent brakes and auto accidents? A GPS system and getting lost?

Submitted by Paul Alper