A Higher Intake of CLA and Vaccenic Acid from Dairy, Beef, Veal and Lamp Could Prevent Subtle Weight Gain in Healthy Middle-Aged Individuals. Is 1.5g/day the Magic Number?

A dairy cow: Does her stomach hold the key to a leaner, healthier life or are CLA and vaccenic acid, the ruminant trans-fatty acids just as bad as their grainy cousins?

There are supplements that work and supplements that don't work and then there are those supplements, where nobody can actually tell, whether they belong to the former or the latter category. Conjugated linoleic acid, the ruminant omega-6 trans-fat you will find at particularly high concentrations in milk and meat products from grassfed dairy, unquestionably belongs to the latter category. While we do actually have plenty of in parts almost unsettlingly impressive rodent data (e.g. "CLA Destroys Body Fat & Increases Endurance! But at Which Costs?"), the outcomes of independent  controlled human studies are equivocal; with results ranging from "total failure", to "promising, but not half as impressive as we have expected based on previous rodent studies".

That being said, I was quite intrigued, when I hit onto a recently published study that takes a novel angle on the whole CLA for weight loss issue. One I usually don't like, as it involves a lot of statistical shenanigan, but still appears appropriate in this particular case, where the controlled small scale trials are failing us.

The Nordic Men (and women) love their full-fat dairy - rightly so?

If you are a loyal reader of the SuppVersity, who does not just read the detailed elaborations here on www.suppversity.com, but is also following the latest short news on the SuppVersity Facebook Wall, it probably won't surprise you that the study which is going to be published in the October issue of the European Journal of Clinical Nutrition has been conducted in Northern Europe. After all, you will have noticed that many of the interesting short news items relating to (larger scale) studies on the effects of one or another of the "bad fats" are conducted at universities and research centers in Sweden, Finland, Norway and, as in this case, Denmark - at the Aarhus University, to be precise, where Hansen and his colleagues datasets from the Diet, Cancer and Health study from December 1993 to May 1997. The participants, 160,725 men and women, aged 50–64 years, who were all born in Denmark and had been living in the greater Aarhus or Copenhagen areas, had all completed detailed food frequency questionnaire (FFQ) and a self-administered lifestyle questionnaire, before they underwent a physical examination and a follow up 5-6 years later.

How did the scientists know how much CLA and vaccinic acid the individual food items contained? unfortunately, they didn't. The way by which they calculated / estimated it,  i.e, by combining the content of r-TFAs in milk fat (data based on another Danish study) with the content of milk fat in dairy products given by the Danish food composition tables and using the values of r-TFA content in ruminant meat products representative of the supply in Denmark, does however make sense to me. The resulting averages should therefore be relatively reliable.

Based on the 77 food items of the food frequency questionnaires which contained ruminant trans-fatty acids R-TFA (this includes both CLA, as well as vaccinic acid which can be converted to CLA in the human body; cf. Turpeinen. 2002), i.e.

• dairy products (n=63), 
• ruminant meat products (beef, veal or lamb) (n=2), and
• composite recipes containing both dairy and ruminant meat (n=12) 

Hansen et al. calculated the average r-TFA intake of each of the 57053 subjects with complete datasets and correlated them with the participants changes in body weight and waist circumference (WC) over the 5-year period to the follow-up.

A massive amount of data suggest minimal amounts of r-TFA are necessary

As the subheading to this paragraph already reveals, the result of the all this statistical shenanigan suggest that the ruminant trans-fatty acid intake from foods, not supplements, does have a beneficial effect on the change in total body weight (an ameliorating effect on weight gain, to be precise).

Figure 1: Absolute intake of ruminant R-TFA (in g/day) and changes in weight; adjustment for sex, age, height, baseline weight, smoking, alcohol intake, education, weighted intake of foods containing high amounts of I-TFA (g/day) and in women, menopausal status and hormone replacement therapy (Hansen. 2013).

A brief glance at the graphs in figure 1 will yet also tell you that their effect on body fatness (as indicated by changes in visceral adipose tissue), is negligible, not to say non-existent. In a way you may say that this is a good thing, because the turning point at a daily r-TFA intake of >1.5g/day, where the restricted cubic spline (that's a statistical fit into the data; figure 1, solid lines) seems to indicate that r-TFA intakes of more than 1.5g/day would precipitate weight gain, is thus absent as well.

Figure 2: Relative intake of R-TFA (in % of total energy intake) and changes in waist circumference. Solid lines: restricted cubic spline with five knots; Dashed lines: 95% confidence interval; same adjustments as in figure 1(Hansen. 2013)

In addition, if we do also consider total energy consumption and the contribution of r-TFAs to the latter (see figure 2), it becomes obvious that we cannot neglect the profound widening of the 95% confidence interval in figure 1 (dashed lines), which tells us that some of the high r-TFA consumers did get even leaner, while others did gain a significant amount of weight. Adjusted for caloric intake and the other confounding variables this effect vanishes and a trend towards lower / even no body weight gain in high r-TFA consumers becomes visible (even within the higher intakes, where the confidence interval widens, due to the lower number of participants, but does not change the general trend). The beneficial effect on waist circumference, however, remains negligible.

So what, if anything, can we learn from these results?

At first sight, the results of the study at hand seem to stand in line with what you have read in "Fat Advantage: 61% Lower Rates of Metabolic Syndrome in High Fat Dairy Lovers", here at the SuppVersity exactly one week ago. It even appears to provide a mechanism by which the high fat dairy products could exert their highly desirable anti-obesity effects, if the high CLA + vaccenic acid (r-TFAs) consumers in the Hansen study were not just the subjects who gained the least weight (measured against their nutrient intake and adjusted for all sort of other confounding factors), but also those with the lowest increase in visceral adipose tissue.  

If that were the case, however, the graph on the right hand side of figure 2 should have at least some kind of slope. Since it hasn't, we must assume that the beneficial health effects of r-TFAs are either (a) not brought about by changes in visceral obesity, (b) the latter are not appropriately quantified by simply measuring the waist circumference or (c) in view of the fact that we are not talking about "weight loss", but rather a prevention of the (partly probably age induced) increase in weight gain a stable waist circumference has to be considered a "success", already.

The scale is an unreliable tool to judge visceral obesity. And even a measuring tape can be misleading, if you are really "skinny fat".

Personally, I tend towards a combination of all three. First of all even moderate weight gain has been shown to increase the risk of impeding metabolic syndrome. The weight stability over >5years in the high r-TFA consumers must therefore be considered to be prognostic of a lower risk of metabolic syndrome. Secondly, visceral does not necessarily equal abdominal fat. Especially in older individuals the gynoid fat areas contribute to visceral obesity, as well. Moreover, we all know the skinny fats, men and women with a relatively large amount of highly inflammatory visceral fat and normal or even low waist circumferences also known as "normal weight obese"; cf. Romero-Corral. 2010).

And thirdly and most importantly: Weight loss is mainly an issue for people who are already overweight or obese. For best-agers who are still in form (and in Denmark there are such people ;-), success is better defined by maintaining the muscle mass you have, not accumulating additional (visceral) body fat and leading an overall healthy lifestyle. That ruminant trans-fatty acids can, maybe even should be a part of the dietary side of this healthy life-style is therefore the main take home message of this study.

What should not be forgotten, however, is the fact that this study was at least in parts supported by the Danish Dairy Research Foundation, certainly not an organization with a particular interest in "bad news" on vaccenic acid, conjugated linoleic acid and dairy products in general, right?


References:

• Hansen CP, Berentzen TL, Halkjær J, Tjønneland A, Sørensen TI, Overvad K, Jakobsen MU. Intake of ruminant trans fatty acids and changes in body weight and waist circumference. Eur J Clin Nutr. 2013 Oct;66(10):1104-9. doi: 10.1038/ejcn.2013.87.
• Romero-Corral A, Somers VK, Sierra-Johnson J, Korenfeld Y, Boarin S, Korinek J, Jensen MD, Parati G, Lopez-Jimenez F. Normal weight obesity: a risk factor for cardiometabolic dysregulation and cardiovascular mortality. Eur Heart J. 2010 Mar;31(6):737-46.
• Turpeinen AM, Mutanen M, Aro A, Salminen I, Basu S, Palmquist DL et al. Bioconversion of vaccenic acid to conjugated linoleic acid in humans.Am J Clin Nutr2002;76: 504–510.

Fat Advantage: 61% Lower Rates of Metabolic Syndrome in High Fat, 101% Higher Rates in Low Fat Dairy Lovers

"Got milk" is not the question health conscious supermen and -women should pose. "Got full fat milk, fermented dairy and cheese" is the line to remember (the original image was part of the "Got Milk Campaign")

While diet fads come and go, the advice the wise (not seldom obese or otherwise sick) experts on the boards and panels of our well-meaning governments is calling "dietary recommendations" is about as resistant to reform as the dreaded MSRA strains are to the antibiotics doctors are throwing at you whenever you sneeze. Against that background the recent trend we are seeing with respect to an increase in the recommended amount of dietary protein does almost amount to a quantum leap; a leap with a significant caveat, however. A fat caveat, so to say:

"A healthy diet includes [...] lean meats, poultry, fish, beans and fat-free or low-fat dairy products" (NIH. 2013).

Luckily, you as a SuppVersity reader do not have to rely on the NHI's thwarted interpretations of the latest research they claim to use, when they are "turning discovery into health" (no joke, this is a literal citation from the footer of the NHI website!), but can compare it to my thwarted interpretations of the latest research and cherry picked data ;-)

Cherry pick of the day: Longitudinal large scale study on dairy intake and metabolic health

 For Today, this means that you get to enjoy the latest results of a large scale observational study from the University of Sydney that's based on datasets from the Blue Mountains Eye Study (BMES) a population-based cohort study of common eye diseases and other health conditions in residents aged 49 years and over in the Blue Mountains area, west of Sydney. A longitudinal study the baseline information was obtained in 1992/1994 from  and complemented by follow-up ten years later.

The data sets included food frequency questionnaires, as well as anthropometric and biochemical assessments all of which were included in the present analysis of the association betweenn dairy consumption with the ten-year incidence of Metabolic syndrome (MetSyn) and type 2 diabetes. What's so special about this dataset, is that the food questionnaires were actually detailed enough to assess the effects of full- and low-fat dairy, separately - a very important advantage, as a cursory glance at the data in figure 1 reveals.

Figure 1: Odds ratios (95% confidence intervals) of incident metabolic syndrome according to quartiles of reduced/low fat,
regular fat and total dairy product intake (data based on Louie. 2013; adjustments for age and sex (basic model), smoking status, physical activity (metabolic equivalents), dietary glycemic load, fibre from vegetables, total energy intake and family history of type 2 diabetes (model 1) and calcium (model 2))

While the standard analysis for total dairy consumption (figure 1, left) yielded neither conclusive, nor statistically significant results (the p-values for the different models can be found in the upper right corner of the respective graphs). The categorization into low- and high fat dairy and the adjustments for age and sex (basic model), smoking status, physical activity (metabolic equivalents), dietary glycemic load, fibre from vegetables, total energy intake and family history of type 2 diabetes (model 1) and calcium (model 2) yields very clear and, after adjustment for calcium intake, pretty unflattering result the formulators of the afore mentioned "dietary recommendations" will probably file in their already bristling "statistical outliers"-folder:

• after adjustment for calcium intake subject in quartiles 2 / 3 / 4 of low-fat dairy are 50% / 145% / 101% more likely to be struck by metabolic syndrome, than those in the lowest quartile of low fat dairy intake (p = 0.043), while
• subjects in the highest quartile of full-fat dairy intake are - depending on the adjustments made -  48% / 59% / 61% less likely (base model / model 1 / model 2) to suffer frommetabolic syndrome, than those in the lowest quartile of high fat dairy intake (p-values:  0.018 / 0.004 / 0.004)

Yet while the scientists are well aware, that these results stand in stark contrast to the initially cited dietary recommendations, is it not this contrast that surprises them, but rather the fact that a similar significant benefit was not observed for type II diabetes, which is, after all, one of the hallmark features of the rather loosely defined triad of obesity, insulin resistance and cardiovascular disease(s), we usually refer to as 'metabaolic syndrome':

"Due to its higher saturated fat content, regular fat/high fat dairy products were previously believed to increase the risk of type 2 diabetes as a high saturated fat intake is associated with insulin resistance . However, cohort studies and a meta-analysis now suggest otherwise, with higher regular fat/high fat dairy consumption being considered mostly neutral or protective for type 2 diabetes. The results of the present study are consistent with these findings that higher regular fat dairy consumption may be protective of MetSyn and type 2 diabetes. The potential harmful effects of higher saturated fat from regular fat dairy products may have been offset by the protective components of regular fat dairy such as trans-palmitoleate, a fatty acid nearly unique to ruminant foods. Circulating level of trans-palmitoleate was shown to be significantly associated with reduced risk of type 2 diabetes (Q5 vs Q1: 62% reduced risk, p-trend < 0.001). Moreover, the protective effect of trans-palmitoleate may be exerted via the suppression of hepatic fat synthesis, where the latter was strongly associated with insulin resistance." (Louie. 2013; my emphases)

In view of these mechanism, it is all the more surprising that the study at hand and many previous studies didn't find any significant correlations between (regular fat) dairy intake and type II diabetes.

Reduction in metabolic risk, but no effect on type diabetes? Hold on...

Wolverine could be the only face of the "Got Milk" campaign who does not have to care about potential negative health effects of homogenized milk.

And upon a cursory read of the latest literature it does in fact seem as if "null findings" like this, were nothing special. Only recently by Sluijs et al. who had analyzed datasets from a nested case-cohort within 8 European countries of the European Prospective Investigation into Cancer and Nutrition Study (n = 340,234; 3.99 million person-years of follow-up) includind a random subcohort (n = 16,835) and incident diabetes cases (n = 12,403; cf. Slujis. 2013):

"This large prospective study found no association between total dairy product intake and diabetes risk. An inverse association of cheese intake and combined fermented dairy product intake with diabetes is suggested, which merits further study." (Sluijs. 2013)

If we do yet take a closer look at the actual results the actually not so surprising truth is that there was a statistically significant inverse association with diabetes for cheese (p = 0.01) and fermented dairy (p = 0.02).

An association that suggests a 12% reduction in diabetes risk in those study participants who consumed the most cheese and fermented dairy (cheese, yogurt, and thick fermented milk)

And since you all know your real foods, I guess I don't have to tell you that despite the fact that there are low fat varieties of cheese yogurts and other fermented milk products, 90% of them contain way more than the 1.5% let alone 0.1% fat the allegedly healthy low fat "milk" is boasting of. Mere coincidence? I don't think so. Reason to assume that low-fat milk will make you sick? No, but certainly not an argument to avoid the full-fat variety simply because it contains fat (which is the only argument the average dietitian has to favor low- over full-fat dairy products).

Mutant Milk!? New Research Fuels the Flames on Hushed Up Concerns About Ill Health Effects of Homogenized Milk 

Ask Dr. Andro: Are Colostrum and Milk Products in General Healthy Muscle Builders, a Waste of Money or Toxic Waste?

All about milk: Browse past news and articles at the SuppVersity

^ Suggested reads

Additional recent dairy science:Similar beneficial findings for all-cause mortality and fermented dairy (yet inconclusive results for CVD and diabetes) come from the recently published Whitehall II study (4526 subjects,72 % men, mean age 56 years; Soedamah-Muthu. 2013) and for dairy intake during adolescents and diabetes (-38% risk reduction for 2 servings per day or more) from a reanalysis of somewhat questionable data (who remembers exactly how much dairy he had during his adolescence?) from the Nurses' Health Study II cohort that comprises 37,038 women who completed a food-frequency questionnaire about their diet during high school were followed from the time of return of the questionnaire in 1998-2005 (Malik. 2013).


References:

• Louie JC, Flood VM, Rangan AM, Burlutsky G, Gill TP, Gopinath B, Mitchell P. Higher regular fat dairy consumption is associated with lower incidence of metabolic syndrome but not type 2 diabetes. Nutr Metab Cardiovasc Dis. 2013 Sep 26. pii: S0939-4753(12)00193-7. 
• Malik VS, Sun Q, van Dam RM, Rimm EB, Willett WC, Rosner B, Hu FB. Adolescent dairy product consumption and risk of type 2 diabetes in middle-aged women. Am J Clin Nutr. 2011 Sep;94(3):854-61.
• NIH. Health in the News: Love Your Heart. February 2013. < http://newsinhealth.nih.gov/issue/feb2013/feature1 > retreived Oct 02, 2013.
• Soedamah-Muthu SS, Masset G, Verberne L, Geleijnse JM, Brunner EJ. Consumption of dairy products and associations with incident diabetes, CHD and mortality in the Whitehall II study. Br J Nutr. 2013 Jun 7:1-9.
• Sluijs I, Forouhi NG, Beulens JW, van der Schouw YT, Agnoli C, Arriola L, Balkau B, Barricarte A, Boeing H, Bueno-de-Mesquita HB, Clavel-Chapelon F, Crowe FL, de Lauzon-Guillain B, Drogan D, Franks PW, Gavrila D, Gonzalez C, Halkjaer J, Kaaks R, Moskal A, Nilsson P, Overvad K, Palli D, Panico S, Quirós JR, Ricceri F, Rinaldi S, Rolandsson O, Sacerdote C, Sánchez MJ, Slimani N, Spijkerman AM, Teucher B, Tjonneland A, Tormo MJ, Tumino R, van der A DL, Sharp SJ, Langenberg C, Feskens EJ, Riboli E, Wareham NJ; InterAct Consortium. The amount and type of dairy product intake and incident type 2 diabetes: results from the EPIC-InterAct Study. Am J Clin Nutr. 2013 Aug;96(2):382-90.