by Marion Nestle

Currently browsing posts about: Fats-and-oils

Oct 24 2011

On Denmark’s “fat tax”

I have a commentary in the October 23 issue of New Scientist (UK):

Cover of 22 October 2011 issue of New Scientist magazine

World’s first fat tax: what will it achieve?

Enviably healthy Denmark is leading the way in taxing unhealthy food. Why are they doing it, and will it work

THE Danish government’s now infamous “fat tax” has caused an international uproar, applauded by public health advocates on the one hand and dismissed on the other as nanny-state social engineering gone berserk.

I see it as one country’s attempt to stave off rising obesity rates, and its associated medical conditions, when other options seem less feasible. But the policies appear confusing. Why Denmark of all places? Why particular foods? Will such taxes really change eating behaviour? And aren’t there better ways to halt or reverse rising rates of diet-related chronic disease?

Before getting to these questions, let’s look at what Denmark has done. In 2009, its government announced a major tax overhaul aimed at cushioning the shock of the global economic crisis, promoting renewable energy, protecting the environment, discouraging climate change, and improving health – all while maintaining revenues, of course.

The tax reforms make it more expensive to produce products likely to harm the environment and to consume products potentially harmful to health, specifically tobacco, ice cream, chocolate, candy, sugar-sweetened soft drinks, and foods containing saturated fats.

Some of these taxes took effect last July. The current fuss is over the introduction this month of a tax on foods containing at least 2.3 per cent saturated fat, a category that includes margarine, salad and cooking oils, animal fats, and dairy products, but not – thanks to effective lobbying from the dairy industry – fluid milk.

Copenhagen is the home of René Redzepi’s Noma, voted the world’s best restaurant for the past two years. To Americans, “Danish” means highly calorific fruit – and cheese-filled breakfast pastries. Despite such culinary riches, the Nordic nation reports enviable health statistics and a social support system beyond the wildest imagination of inhabitants of many countries. Danish citizens are entitled to free or very low-cost childcare, education and healthcare. Cycle lanes and high taxes on cars make bicycles the preferred method for getting to school or work, even by 63 per cent of members of the Danish parliament, the Folketing.

Taxes pay for this through policies that maintain a relatively narrow gap between the incomes of rich and poor. The Danish population is literate and educated. Its adult smoking rate is 19 per cent. Its obesity rate is 13.4 per cent, below the European average of 15 per cent and a level not seen in the US since the 1970s. Denmark has long used the tax system to achieve health goals. It has taxed candy for nearly 90 years, and was the first country to ban trans-fats in 2003.

Because its level of income disparity is relatively low, the effects of health taxes are less hard on the poor than in many other countries. But the Danes want their health to be better. Obesity rates may be low by US standards, but they used to be lower – 9.5 per cent in 2000. Life expectancy in Denmark is 79 years, at least two years below that in Japan or Iceland. The stated goal of the tax policies is to increase life expectancy as well as to reduce the burden and cost of illness from diet-related diseases.

Like all taxes, the “health” taxes are supposed to raise revenue: 2.75 billion Danish kroner annually ($470 million). The tax on saturated fat is expected to account for more than one-third of that. Since all food fats – no exceptions – are mixtures of saturated, unsaturated, and polyunsaturated fatty acids, the tax will have to be worked out food by food. Producers must do this, pay the tax, and pass the cost on to consumers.

Taxes on cigarettes are set high enough to discourage use, especially among young people. But the food taxes are low, 0.34 kroner on a litre of soft drinks, for example. The “fat” tax is 16 kroner per kilogram of saturated fat. In dollars, the taxes will add 12 cents to a bag of crisps and 40 cents to the price of a burger. Whether these amounts will discourage purchases remains to be seen.

Other countries are playing “me too” or waiting to see the results of Denmark’s experiment. Hungary has imposed a small tax on sweets, salty snacks, and sugary and caffeinated drinks and intends to use the revenues to offset healthcare costs. Romania and Iceland had such taxes but dropped them, whereas Finland and Ireland are considering them. Surprisingly, given his party’s anti-nanny state platform, UK prime minister David Cameron is suggesting food taxes to counter the nation’s burgeoning obesity crisis. The US has resisted calls for taxes on sugar-sweetened beverages, not least because the soft drink companies spent millions of dollars on defeating such proposals.

Leaving aside the usual criticisms, such as the impact on poorer people, I have a different reason for being troubled by tax interventions. They aim to change individual behaviour, but do little to change the behaviour of corporations that make and market unhealthful products, spending vast fortunes to make them available, desirable and socially acceptable.

Today, more and more evidence demonstrates the importance of food environment factors, such as processing, cost and marketing, in influencing food choices (The Lancet, DOI: 10.1016/S0140-6736(11)60813-1). Raising taxes is one way to change that environment by influencing the cost to the consumer. But governments seriously concerned about reducing rates of chronic disease should also consider ways to regulate production of unhealthy products, along with the ways they are marketed.

In the meantime, let us congratulate Denmark on what could be viewed as a revolutionary experiment. I can’t wait to see the results.

Marion Nestle is the author of Food Politics and What To Eat and is the Paulette Goddard Professor of Nutrition, Food Studies, and Public Health at New York University

Aug 16 2011

The fuss over saturated fat

I keep getting questions about saturated fat.  Does it really pose a health risk?  If so, how serious a risk?  And isn’t eating real food OK even if it contains saturated fat?  Good questions.  Here are a couple of recent examples:

Reader #1: I think that the idea that saturated fats in meat and dairy are unhealthful is errant, based on correlative – not causative – scientific studies…I propose that instead of demonizing one nutrient over another, we favor whole, high-quality foods of both animal and plant origin…designed by nature (and thousands of years of trial and error) to meet the needs of their respective populations. What do you say?

Reader #2: I wonder how the government can be so focused on low-fat milk. Is that really such a huge problem? Isn’t the bigger problem that the state of NY is telling people pretzels make a healthy snack? Isn’t it soda and cheese doodles and eating every dinner from a box that is the problem? Whole milk, really? I’d appreciate your clarity on this… we are full fat milk and cheese people, and all of this perplexes me.

I can understand why anyone might be confused about saturated fat.  Food fats are complicated and it helps to be a biochemist (as I once was) to sort out the issues related to degree of saturation and whether the omegas are 3, 6, or 9 (I explain all this in the chapter on fats and in an appendix to What to Eat).

And yes, the science is complex and sometimes seems contradictory but scientific committees for the past 50 years have concluded one after another that substituting other kinds of fatty acids for saturated fatty acids would reduce levels of blood cholesterol and the risk for coronary heart disease.

And no, those scientists cannot have all be delusional or paid off by the meat or dairy industries.  They—like scientists today—mostly call the science the way they see it.

What makes the research especially hard to sort out is that all food fats—no exceptions—are mixtures of saturated, unsaturated, and polyunsaturated fatty acids (just the proportions differ), that some saturated fatty acids raise blood cholesterol levels more than others do, and that one kind—stearic acid—seems neutral with respect to blood cholesterol.

But overall, the vast majority of expert committees typically conclude that we would reduce our heart disease risks if we kept intake of saturated fat below 10% of calories, and preferably at or below 7%.   On average, Americans consume 11-12% of calories from saturated fat, which doesn’t sound too far off but the average means that many people consume much more.

As is often the case with studies of single nutrients, research sometimes comes to different conclusions.  Several studies—all quite well done—have appeared just in the last year or so.

One of these is a meta-analysis (a review of multiple studies). It concludes:

…there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD [coronary heart disease] or CVD [cardiovascular disease]. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat [my emphasis].

What saturated fat gets replaced with is the subject of three other well conducted studies that come to a different—the mainstream—conclusion.  One, another recent meta-analysis, confirms decades of previous observations (sorry about the annoying abbreviations):

These findings provide evidence that consuming PUFA [polyunsaturated fatty acids] in place of SFA [saturated fatty acids] reduces CHD events in RCTs [randomized clinical trials]. This suggests that rather than trying to lower PUFA consumption, a shift toward greater population PUFA consumption in place of SFA would significantly reduce rates of CHD.

Translation: replacing saturated fats with polyunsaturated fats would be healthier.

Another meta-analysis comes to the same conclusion:

The associations suggest that replacing SFAs with PUFAs rather than MUFAs [monounsaturated fatty acids] or carbohydrates prevents CHD over a wide range of intakes.

A very recent consensus statement concludes:

the evidence from epidemiologic, clinical, and mechanistic studies is consistent in finding that the risk of CHD is reduced when SFAs are replaced with polyunsaturated fatty acids (PUFAs). In populations who consume a Western diet, the replacement of 1% of energy from SFAs with PUFAs lowers LDL cholesterol [the “bad” kind] and is likely to produce a reduction in CHD incidence of ≥2–3%. No clear benefit of substituting carbohydrates for SFAs has been shown, although there might be a benefit if the carbohydrate is unrefined and has a low glycemic index.

The advisory committee to the 2010 Dietary Guidelines for Americans reviewed this and other research relating saturated fatty acids to heart disease risk and concluded:

Cholesterol-raising SFAs, considered SFA minus stearic acid…down-regulate the low density lipoprotein (LDL) receptor by increasing intracellular cholesterol pools and decreasing LDL cholesterol uptake by the liver.

The committee’s research review addressed the question, “What is the Effect of Saturated Fat Intake on Increased Risk of Cardiovascular Disease or Type 2 Diabetes, Including Effects on Intermediate Markers such as Serum Lipid and Lipoprotein Levels?”  It judged the evidence strong

that intake of dietary SFA is positively associated with intermediate markers and end point health outcomes for two distinct metabolic pathways:

1) increased serum total and LDL cholesterol and increased risk of CVD and

2) increased markers of insulin resistance and increased risk of T2D [type-2 diabetes]. Conversely, decreased SFA intake improves measures of both CVD and T2D risk.

The evidence shows that 5 percent energy decrease in SFA, replaced by MUFA or PUFA, decreases risk of CVD and T2D in healthy adults and improves insulin responsiveness in insulin resistant and T2D individuals.

How much saturated fat might increase the risk of heart disease or type-2 diabetes depends on how much you eat as well as what you eat.

What to do to reduce your dietary risks for heart disease?  Take a look at the top 15 sources of saturated fats in U.S. diets:

  • Regular cheese
  • Pizza
  • Grain-based desserts (cakes, cookies, pies, pop-tarts, donuts, etc)
  • Dairy desserts
  • Chicken and chicken mixed dishes (e.g. fingers)
  • Sausage, franks, bacon, and ribs
  • Burgers
  • Mexican mixed dishes
  • Beef and beef mixed dishes
  • Reduced fat (not skim) milk
  • Pasta and pasta dishes
  • Whole milk
  • Eggs and egg mixed dishes
  • Candy
  • Butter
  • Potato/corn/other chips
  • Nuts/seeds and nut/seed mixed dishes
  • Fried white potatoes

Explanation: These foods do not necessarily have the most saturated fat.  If the list surprises you, recall that all food fats have some saturated fats.  These foods are leading sources because they contain some saturated fat and many Americans eat them.

It is surely no coincidence that these foods are also among the leading sources of calories in U.S. diets.  The health effects of diets, let me repeat, have to do with quantity as well as quality.

If you do not habitually eat most of the foods on this list, and are not gaining weight, saturated fatty acids are much less likely to be a problem for you.

And just because saturated fats raise the risk of heart disease does not mean they are poisons.   Eat fats.  Just not too much.

 

 

 

Mar 22 2010

Saturated fat vs. heart disease: current state of the science

Despite recent publications finding no correlation between intake of saturated fat and coronary heart disease (CHD) – see, for example, the recent meta-analysis in the American Journal of Clinical Nutrition – the debates over the role of saturated fat continue.

In that same issue of the Journal, another study says that reducing saturated fat only works if you replace it with something better.  If you replace saturated fat with carbohydrates, the effects on heart disease will be worse.

The fat story is not simple (in What to Eat, I explain the biochemistry of food fats in the chapter on fats and oils and in an appendix).  The main reason for the complexity is that different kinds of fats do not occur separately in foods.

Without exception, food fats are mixtures of  three kinds of fatty acids: saturated (no double bonds and solid at room temperature), monounsaturated (one double bond), and polyunsaturated (two or more double bonds and liquid at room temperature).  Food fats just differ in proportions of the three kinds.

Meat, dairy, and egg fats generally are more saturated.  Plant fats and oils are generally more unsaturated.

How to make sense of the saturated fat story? An expert panel from WHO and FAO just produced a new review of the evidence.  The panel evaluated CHD morbidity and mortality data from epidemiological studies and controlled clinical trials.  It found:

  • Convincing evidence that replacing saturated fat with polyunsaturated decreases the risk of CHD.
  • Probable evidence that replacing saturated fat with largely refined carbohydrates (starch and sugar) has no benefit and even may increase the risk of CHD.
  • Insufficient evidence relating to the effect on the risk of CHD of replacing saturated fat with monounsaturated fats or whole grain carbohydrates, but a trend suggesting that these might decrease CHD risk.
  • Possible positive relationship between saturated fat and increased risk of diabetes.
  • Insufficient evidence for establishing any relationship of saturated fat with cancer.

The panel’s recommendations:  (1) Replace saturated fat with polyunsaturated fats (omega-3 and omega-6) in the diet, and (2) Limit saturated fat to 10% of daily calories or less.

Translation: Eat less animal fat and replace it with vegetable fats.

Historical note: These are precisely the same recommendations that have been standard in the U.S. for at least fifty years.  This was good advice in the late 1950s.  It is still good advice.

UPDATE, March 22,2011:  Another major review has just come to precisely the same conclusions, this one from an international expert panel.  It also suggests areas for future research.  See American Journal of Clinical Nutrition 2011;93:684-88.

Jan 25 2010

A quick Q and A: sugars and fats

I wish I could answer all of the questions that come into Feedback or Comments, but I cannot except occasionally.  It’s a rainy day in New York and today seems to be one of those occasions.

Q: Does the caloric value of a food change when it’s cooked?  In his latest book, “Catching Fire: How Cooking Made us Human,” Harvard Primatologist Richard Wrangham argues that cooking foods changes the available nutrient content and actually raises the available calories.

A:  The rules of physical chemistry tell us that matter cannot be destroyed or created so the number of calories available in a food does not change with temperature.  What can change is our ability to use (digest, absorb) the calories that are there as well as our desire to eat the foods.  Cooking makes the calories in potato starch more available, for example, but has hardly any effect on the calories in meat.  Both, in my opinion at least, taste better cooked.    But cooked or not, the calorie differences will be small and unlikely to account significantly for weight change.

The nutrient situation is also complicated.  Cooking destroys some nutrients (vitamin C is a good example) but makes others more available (beta-carotene).  This is another reason why nutritionists are always advising variety in food intake.  Variety applies to cooked and raw, as well.

Q.  Can you please explain what benefits, if any, there are in using a “natural” sweetener, e.g. agave, over regular sugar?  Are there any differences in terms of glucose/fructose makeup?

A.  Agave is more expensive so you probably won’t use as much of it.  Beyond that, it is higher in fructose than table sugar or honey.  This is because agave contains inulin, a polymer of fructose, which must be hydrolyzed (broken down by heat or enzymes) to fructose to make the sweetener.  It’s a processed sweetener requiring one hydrolysis step, requiring more processing than honey and less than high fructose corn syrup.  It has the same number of calories as any other sugar, about 4 per gram or 16 per teaspoon.

Q.  Also, you’ve written on a prior blog that fructose is “preferentially” metabolized into fat by the body.  Can you explain in more detail what that means?

A.  More and more evidence suggests that high amounts of fructose in the diet are not good for health.  Fructose occurs naturally in fruit and nobody worries about that because fruits don’t contain all that much and the sugar is accompanies by vitamins, minerals, and fiber that are well worth eating.  Honey, table sugar, and high fructose corn syrup (a misnomer) are about 50% each glucose and fructose.  Glucose and fructose are metabolized differently and some investigators believe that excessive amounts of fructose stress metabolism in ways that encourage fat deposition.  Eating a lot of sugars of any kind is not a great idea, which is why there are so many concerns about soft drinks these days.

Q.  I would appreciate some comments about the “Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease.

A.  The study concludes:  

A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD [coronary heart disease] or CVD [cardiovascular disease]. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat.

This is a review of previous epidemiological studies (not clinical trials).  These fail to find a correlation between consumption of saturated fat and heart disease.  This could be because there is no correlation or there is one but they can’t find it.  My interpretation: even if there is one, it is likely to be small.

I am increasingly convinced that studies of single nutrients – sugar, fructose, saturated fat, or even omega-3s – will give complicated results when removed from their dietary context.  People who eat foods containing a lot of sugars or animal fats eat and behave differently than people who do not, but not so differently that health differences will show up in the kinds of studies scientists are currently able to do.

Keep in mind: nutrition science is exceedingly difficult to do because there are so many factors in foods that affect health and so many behavioral, economic, and social factors that affect what people eat.

All of this is why I find nutrition so interesting but I can understand why others might find it frustrating.

Jan 19 2008

Nothing is simple: sustainable palm oil?

If you eliminate oils with trans fats, you have to replace them with fats with equivalent levels of saturation, and palm oils are highly saturated and work well as substitutes. One consequence of the increased demand for palm oils is destruction of tropical rainforests. “To improve the industry’s image and avert a consumer backlash,” food companies are pushing palm oil producers to go green and promise to produce palm oils sustainably. Will this work? It will be interesting to see.

In the meantime, the New York Times has plenty to say about how using palm oil for fuel drives up the cost of food.

Jan 11 2008

What’s the deal on saturated fat?

A reader, “rj,” sends a link to an article in Men’s Health (“What if bad fat isn’t so bad”), and asks about: “The supposed inconclusive evidence for sat fat being the culprit in atherosclerosis. Personally, I couldn’t find any credentials of the author but nevertheless would be much interested in your thoughts on the matter.”

My thoughts: As I keep saying, nutrition science is complicated and this article, by an excellent science journalist, is the latest in a series by excellent science journalists (see, for example, the recent books by Gary Taubes and Michael Pollan) to point out the inconsistencies in data on saturated fat and heart disease risk. Let me make several quick points: (1) All fats–no exceptions–are mixtures of saturated, unsaturated, and polyunsaturated fatty acids (2) Saturated fats occur in greater proportions in animal fats–meat and dairy foods, (3) Some epidemiologic evidence–but not all–suggests that people who eat a lot of meat and dairy foods have a higher risk of heart disease than people who eat a lot of fruit and vegetables (this is correlation, not causation), (4) The same clinical studies that show how trans fats do bad things to blood cholesterol levels also show that saturated fat does too, although not as much (But: people take in a lot more saturated fat than trans fat), and (5) Saturated fat is a single nutrient and the studies reviewed and discussed by the journalists take saturated fat out of its dietary context.

Out-of-context studies of single nutrients are exceedingly difficult to interpret. At the moment, today’s dietary (not single nutrient) advice is the same as it has been for the last fifty years. As I put it in What to Eat, “Eat less, move more, eat plenty of fruits and vegetables, and don’t eat too much junk food.” Michael Pollan gives exactly the same advice: “Eat food. Not too much. Mostly plants.” Do this, and you really don’t need to give a thought to single nutrients.

I discuss the politics of diet and disease recommendations in my book, Food Politics (now out in a new, expanded edition), and this particular question in “Ask Marion” on Eating Liberally.

Does this help at all? Thanks for asking.

Dec 31 2007

Trans-fat substitutes: How?

Here’s a quick question, just in: “I finally got the chance to finish What to Eat, and I noticed that you didn’t talk about non-hydrogenated margarine in your margarine section. I’m not wondering if it’s better for you because I’m sure it’s still soybean oil with a bunch of stabilizers, but I’m just wondering how it’s made.”

Response: I did actually, but in two other chapters, the next one and the one on fats and oils so the explanation is hard to find. Sorry about that. Here’s the deal: companies use variations of two methods: (1) substitute a highly saturated fat like palm kernal or coconut oils, or (2) mix a totally saturated fat (which will not have any trans) with an unhydrogenated fat (also trans-free) until you get the degree of thickness required. Both methods increase the amount of saturated fatty acids. Saturated fats raise the risk of heart disease, but not as much as trans. So the substitutes are likely to be marginally better than oils with trans.

Nov 7 2007

Trans Fat Dilemmas

I have long talked about trans fat as a calorie distracter. People think “trans fat-free” means “calorie-free” when it most definitely does not. Whatever replaces trans fats will have just as many calories–130 per tablespoon, meaning that each tablespoon is 5% of a day’s average calorie intake. That’s why I either laugh or cry when I see “zero grams trans fat”
on the labels of junk foods. Trans fats raise the risk of heart disease a bit more than do the saturated fats that occur naturally in foods. But trans fats are unnatural and unnecessary and it’s good to get rid of them. Yesterday’s Wall Street Journal explains how food companies are struggling to find replacements that do not increase the amount of saturated fat in processed foods. This, as it turns out, is not so easy to do. I discuss all this in the fats-and-oils chapter of What to Eat, so I’m happy to see the WSJ take it on.