Fat chance science can tell you whether lard is good for you

Saturated fat is deadly!
Epidemiologists, and nutritionists informed by epidemiologists, have been telling us for decades that animal fat causes heart attacks, and that therefore we should cut down on meat consumption. Fat -- saturated fat -- raises our cholesterol, which hardens our arteries, which is when blood clots get stuck, block the artery and cause an attack. Everyone knows this, right?

Lard, solidified pig fat, has been considered among the worst offenders. (Check out this link for great pictures of lard, lard sculptures, old lard advertisements and more, to really get you in the mood.) But, if you are a carnivore, and you try to eat 'right,' you might be interested to know some are now saying that lard is good for you. This according to chefs, researchers and science reporters on the BBC Radio 4 Food Programme Nov 5 episode.

As the program reports, lard is thought of as "...a great big solid block of white fat" with an "appalling public image," it's a "decadent guilty treat" that we've "been taught to fear." The demonizing of lard has worked, at least in Britain where people ate on average 55 grams of the stuff per week in the 1970's, but only 5 grams now. But the program does its best to strip lard of its bad image and get you eating it again.

But oh so good

Borlengo lardo (flatbread with lardo); Wikipedia

Chefs rave about lard. Jeremy Lee, chef at a prime London restaurant called Quo Vadis and interviewed for the program, loves it both for its cooking qualities and its flavor. His Scottish grandmother used to fry pancakes in lard. He remembers them as beautifully crisp on the outside and fluffy in the middle, and he ate them loaded with butter. And, he loves lardo, lard cured with rosemary and other herbs. He recommends a "grilled piece of sour dough bread, hot, with very thin pieces of lardo on it is one of the most delicious things ever."  It does sound great, doesn't it?

Lard has a much higher smoke point than other oils, so it can be much hotter before it starts to break down, which makes it useful for cooking. Asked whether lard tastes piggy at all, Lee says no, it's "clean and pure." He says it's good for browning meat, potatoes fried in lard are great, as are pastries made with lard and because of its higher melting point it spreads flavor nicely around the mouth.

Here in State  College is a wonderful restaurant, Herwig's, named after its very skilled and entertaining owner.  Herwig's is an Austrian restaurant that can match anything found in the old country itself.  In the spirit of today's post we thought we'd point out that every table at Herwig's has a little menu card with one of the restaurant's mottos:  "Where bacon is an herb."

Here's Calvin Trillin waxing poetic about lard in a story about food in Oaxaca, "Land of the Seven Moles," in the Dec 3 New Yorker. His daughter's family is spending a semester there and he describes paying them a visit. He appreciates food. 

She had even figured out what would likely be my favorite restaurant in Oaxaca--a simple place called La Teca, which specializes in the food of the Isthmus of Tehuantepec, the narrowest part of southern Mexico.  The meal at La Teca began, once a shot glass full of mescal was downed, with spectacular garnachas--masa cups topped with a meat-and-onion mixture.  (A couple of days later, while watching a woman prepare garnachas at a market in Llano Park, I discovered one of the secrets of why they taste so good: after assembling each one, she launched it, like a little boat, on a couple of inches of hot lard, occasionally splashing a bit of lard over the gunwales.

Garnachas del Istmo de Tehuantepec; Wikipedia

 If you happen to want to try rendering your own lard at home, the Food Programme has graciously posted instructions on their website. My sister Jennifer, of Polymeadows Farms, just made her own, in fact, from one of the pigs they raised on the farm this summer and fall. Her pie crusts made with lard are fantastic.

Wet home-rendered lard; Wikimedia

              Jen's mincemeat bars, made from home-rendered lard from her pastured pigs and beef from her pastured cattle.  She says that surely makes it health food. 

Ready to eat.

 Guilty pleasures?

Bah humbug, saturated fat is good for you!
There are people, like Stephanie Seneff, a researcher at MIT interviewed for the program, who now believe that saturated fat is the healthiest fat, and that cholesterol should be a big part of our diet. Indeed, she advises us to eat green vegetables piled with fat because they are much healthier that way.

Seneff's website says she began her research career in electrical engineering, particularly computer conversational systems, but her current interest is in the role of diet in diseases like Alzheimer's and autism. One of her recent papers, for example, is called "Nutrition and Alzheimer's disease: The detrimental role of a high carbohydrate diet." She suggests that excess dietary carbohydrates are responsible for dementia, and, in this paper, offers a possible biochemical explanation for how that might be.

And, Gary Taubes, science journalist and one of the wisest critics of epidemiological methods out there, agrees that fats have been given an undeserved bad name and we've been getting the wrong nutrition advice for decades, as proven by the obesity and type 2 diabetes epidemics. Lard and other animal fats, he says, are 1/2 mono-unsaturated fats, so they lower ldl cholesterol ('bad' cholesterol), and raise hdl cholesterol ('good' cholesterol). And, 90% of the mono-unsaturated fat in lard is oleic acid, which is the same fat in olive oil that nutritionists tell us to eat more of.

Only 40% of the fat in lard is saturated, he says, and saturated fat raises both ldl and hdl cholesterol, so "it balances out," and a third of the saturated fat is stearic acid, which is the same fat as in chocolate, which raises our good cholesterol and does nothing to our bad. So, he concludes, if you look at the bulk of fat in lard, it's, in theory, good for us.

Further, "If you take the lard you're eating and replace it with carbohydrates, like pasta or bread, or something that's supposedly good for us, you'll do your heart disease risk factors more harm than good." That's a strange argument. Who would replace fat with pasta?  In general, wouldn't someone who includes these foods in their diet be eating both?  Indeed, diets are complex, and implicating a single dietary component's role in disease is notoriously difficult to do.

Who's right?
As the program points out, the UK Department of Health website still says, ""You should avoid foods containing saturated fats because these will increase your cholesterol levels." So, should we or shouldn't we? Gary Taubes is a very smart journalist, and very convincing when he talks about why epidemiology gets things so wrong (e.g., his 1995 Science article, "Epidemiology Faces Its Limits"). But we've been disappointed recently to see that he's got a new hobbyhorse -- sugar kills -- and he seems now to pick and choose among results, being a lot more sanguine and far less critical about the very same epidemiological methods when the results go his way.  The list of "heart disease risk factors" is extensive by now, all determined by basically the same methods, and including many contradictions (some studies find that butter is good for you, some that it's bad, some that eggs are good, some that they are bad, and so forth), for the epistemological reasons that Taubes has so well described. So, dare we say, it's easy to pick and choose among them.

And the Seneff et al. paper on Alzheimer's opens with this sentence: "It has been well established that the brain of patients with Alzheimer's disease (AD) is characterized by the build-up of a signature plaque containing an abundance of the protein amyloid-β (Aβ)," and the argument builds from there. The single citation for this is a 2002 paper; in fact, in the past decade this has been shown not to be well-established at all. Brains of people with no symptoms of dementia when they die have been found to have the same plaque build-up, and brains of people with dementia have been found to have none. So, again, not so simple.  So, an argument built on this premise does not build confidence.

Indeed, one begins to suspect that ideology is driving the results these guys have chosen to believe about fats. They may well be correct that fats are good for us!  Or at least for some of us.  But it's hard to impossible to know by weighing the available evidence.  And, as we point out here all the time, complex diseases are complex, and there are often multiple pathways to disease.  People are different, and the same basic diet will make some fat and some sick, while being benign for others.

Lardo; Wikipedia

So, should we eat lard or shouldn't we? Epidemiological methods are particularly weak when it comes to nutrition. Diets are complex, people eat, and thrive on, a wide range of diets. So, rather then rely on current science to tell you whether or not to enjoy that lardo sandwich, we suggest you rely on this 2400 year-old piece of advice instead:

All good things in moderation.

Boning up in a hearty way on what to eat!

A June 25 piece in The Atlantic about a paper published in the current issue of the cardiology journal Heart (Li et al.) warns that calcium supplements may do more harm than good.  This would be but one of many times that some standard, obviously good, recommendation for better health proved later not to be true or accurate, even though all such recommendations (even the basic food pyramid!) started out as the results of supposedly good, large-enough studies.

Dietary calcium, the paper reports, is associated with lower risk of cardiovascular disease, but calcium supplements are correlated with increased risk of heart attack.  The authors surmise that this is because dietary calcium trickles into our systems throughout the day while blood levels of calcium from supplements spike once or twice a day, causing too much of the mineral to be deposited in the body at a time. 

Li et al. write that epidemiological studies of the risks and benefits of dietary calcium intake have reported inverse associations between intake and risk of high blood pressure, obesity and type 2 diabetes.  Three prospective studies they cite found that dietary calcium intake was significantly inversely correlated with risk of stroke, and an additional study showed an inverse correlation between dietary calcium and death from heart attack. 

But there are several rather obvious flags to raise: It is notoriously difficult to assess diet, in particular to determine the effects of single dietary components independently of other nutrients because they are never consumed in isolation and quantities are frequently under (or over) reported.  And, in the Li et al. study, they used a self-administered food questionnaire, based on recall of food eaten in the 12 months before the study participants were recruited.  This means that it relied on memory of rather crude quantities in rather crude categories (presumably asking things like how many times a week you drink milk, or eat broccoli, or cheese, and whether they regularly took vitamin/mineral supplements in the last 4 weeks -- data on supplement dosage was not collected). 

For many reasons, including relying on recall and assumptions about the kinds of data that should be collected and so on, dietary studies are far too often difficult to interpret -- and difficult to replicate.  And, in the Li et al., food data collected at the beginning of the study were assumed to apply for the duration of the study, 11 years.  In addition to the difficulties measuring how much calcium people are actually consuming, it's possible that there are systematic differences in the diet and/or lifestyle of people taking supplements vs those getting their calcium only from their diet.  For these and other reasons, dietary studies, including the Heart calcium study, should always be approached with healthy skepticism! That said, let's look at this study in more detail. 

Physicians commonly recommend calcium supplements to elderly patients, particularly to postmenopausal women, to reduce risk of osteoporosis and sometime to improve cholesterol levels.  Hundreds of millions of people take the stuff without any thought to risk.  The authors of the Heart paper prospectively followed 24,000 people in Heidelberg, aged 35-64 years at the start of the study, for 11 years to evaluate the associations of dietary calcium intake and calcium supplements with risk of heart attack, stroke and mortality from cardiovascular disease.

Results After an average follow-up time of 11 years, 354 MI and 260 stroke cases and 267 CVD deaths were documented. Compared with the lowest quartile, the third quartile of total dietary and dairy calcium intake had a significantly reduced MI [myocardial infarction, or heart attack] risk, with a HR [hazard ratio; the chance of MI in those taking supplements vs those not taking supplements] of 0.69 (95% CI 0.50 to 0.94) and 0.68 (95% CI 0.50 to 0.93), respectively. Associations for stroke risk and CVD mortality were overall null. In comparison with non-users of any supplements, users of calcium supplements had a statistically significantly increased MI risk (HR=1.86; 95% CI 1.17 to 2.96), which was more pronounced for calcium supplement only users (HR=2.39; 95% CI 1.12 to 5.12). 

So, a moderately higher dietary calcium intake was significantly associated with lower risk of MI -- but the authors report that this became non-significant for men, and more significant for women with increased calcium.  Presumably, the authors say, because of unmeasured confounding nutrients; maybe so, but maybe this is a way to wriggle out of uncomfortable non-results.  They found no association between total, dairy, or non-dairy calcium intake and CVD mortality.  And, they found a significantly increased risk of MI among users of supplements, with a larger effect for people who used supplements only, suggesting to the researchers that the supplements themselves are the important risk factor.  There have been other studies who did not find this association.

Li et al. suggest that if the effect is real, it may be because of an effect of serum calcium levels on vascular calcification.  Other studies have found associations between serum calcium and "some predictive biomarkers of CVD, such as fasting insulin and lipid measures."  So, it's possible that this is real.

But keep in mind that 354 heart attacks in 24,000 people, over 11 years, is a 1% risk.  And if we think about annual risk rather than risk for the entire length of the study, that's 32 heart attacks per year in the 24,000 subjects, or a risk of about 0.1% per year.  Don't know about you but that strikes us as very low risk.  Even those taking supplements were in fact at an absolute low risk.

On a population level, however, if the results are real-- and remember there are serious limitations to this study -- this translates into real excess heart attacks in real people.  So, what are people taking calcium supplements for bone health supposed to do?  Chuck their pills because there's a slight chance they'll cause a heart attack, based on a rather iffy study, or keep taking them because many studies have shown supplements do improve bone density and decrease risk of fractures?  How significantly isn't completely clear, nor is it clear to us whether supplements improve bone health more effectively than dietary calcium.  Perhaps it would be most sensible to chuck the pills and eat more yogurt.

However, it is possible that the benefit of calcium supplements in both relieved morbidity and reduced mortality from the benefits to bone health far outweigh the small, rather ephemeral or tentative excess heart disease risk.  Indeed, lower physical activity because of bone brittleness (which could have been ameliorated by calcium) would be expected to lead to more obesity and greater heart disease risk.  But then there is another finding by a huge study, that such dietary supplements raised the risk of kidney stones.

This is the kind of dilemma epidemiological data like these often create for people having to balance risk and risk factors for many possible outcomes as they make dietary, life style and medicinal decisions about their lives. And when the media report these kinds of studies irresponsibly and uncritically, this does a disservice to the public who must make these decisions.

And, in the end, we have another example of hardly any bang for a great lot of bucks.  Factors strong enough to worry about as a rule can be found with small enough studies to be affordable, sparing the funds for addressing really important issues.  But spending more for less is becoming so widespread in the way science is being done these days that perhaps its more the rule than the exception.

Lousy dietary advice? Don't blame the newspapers! Or, not only the newspapers.

All those dietary recommendations published in newspapers every day?  Anchovies are aphrodisiacs, sassafras tea cures the common cold, antioxidants prevent every known disease and will let you live forever, and so on ad infinitum.  Should we believe them?  A paper published in the journal Public Understanding of Science, and discussed on BBC radio's Material World, "The quality of the evidence for dietary advice given in UK national newspapers," takes on that question.

The authors looked at every article in every issue of the top 10 newspapers published in the UK in a random week, and assessed the quality of the health claims.

Articles, which could be features, news reports or comment pieces relating to nutrition, in the main body or in any additional supplements, were identified. Examples of article titles include: “Slimming news” and “Diet that fights kidney disease.” The criterion for inclusion was that: the article had to make a “health claim” about a food or drink which could be interpreted by the reader as advice. A health claim is defined as a “claim that states, suggests or implies that a relationship exists between a food category, a food or one of its constituents and health” (EC Regulation, 2006). For example, “red wine causes breast cancer” would constitute a dietary health claim (hereafter referred to as a “claim”) in the same way as “don’t drink red wine – it causes breast cancer” would. 

The authors then evaluated the claims by looking for supporting papers in PubMed, and graded the evidence by two different systems.  In 37 articles with dietary advice in the chosen week, there were 111 total claims, more than 3 per article on average.  Of these claims, the paper reports that 68 - 72% had no supporting evidence.  What are they teaching in journalism classes these days??

Given the extent of the obesity problem in the UK, the authors are unhappy to find that newspapers are so flippant about dietary advice.  They cite polls that show that the majority of the public believes that scientists are always changing their minds about what's true, so the best advice is to not listen to them and to eat what you want.  The authors blame this state of affairs on newspapers.

Indeed, one of the guests discussing this paper on Material World was Roger Highfield, journalist and editor of New Scientist magazine.  He wasn't at all surprised by the findings, but defended the press, saying that 'journalists are not there to issue truths, they are there to sell newspapers'.

So, there's an obesity epidemic because newspapers print irresponsible dietary advice?  Not likely. Let's agree that newspapers do print irresponsible dietary advice, but demonstrating this by weighing what's printed against scientific reports is based on an incorrect assumption that what's printed in scientific journals themselves about diet is 'true'.

As one of the co-authors of the study pointed out, dietary research is just not very rigorous.  In part this is because nutritionists haven't figured out how to credibly measure what people eat; in part it's because nutrition science is based on reducing complex foods down to single components in the lab, but it's the complex food that people eat, in combination with other complex foods, not single components; and in part it's the problem we talk about here on MT all the time -- our scientific methods aren't up to assessing complexity on its own terms.  As with genetic results, dietary results are often not replicable, or are overturned by the next big study.

So, yes, newspapers do do a lousy job of reporting dietary stories.  But, most often those stories are based on science that is confusing at best, and irresponsible at worst.

One lesson for the public (and scientists, too) is that changing our minds is exactly what science is about!  If not, everything would be known by now, and we'd be out of work.  Science has to work from, and hence to some extent 'believe in' a current explanation for things, because that is what gives us the framework for further understanding.  But it becomes our fault when we boast and trumpet too much, as we're encouraged to do by the system and by, yes, journalists who hunger for a simple story to headline. And, being only human, by taking  strong positions we back ourselves into corners that we then feel the need to defend.

The best dietary advice?  Moderation in all things.  Including what we say about those things.