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My most recent column in the San Francisco Chronicle appeared later than usual (March 14) so I forgot to post it when it came out.  It deals with Listeria in pregnancy:

A guide to avoiding Listeria

Nutrition and public policy expert Marion Nestle answers readers’ questions in this monthly column written exclusively for The Chronicle. E-mail your questions to food@sfchronicle.com, with “Marion Nestle” in the subject line.

Q: I miscarried at 19 weeks of pregnancy. My doctor said my placenta was infected with Listeria, only her second case in 20 years of practice. I am your typical Bay Area food lover. I thought if I knew the sources of most of my food, I’d be safe. What is safe for pregnant women to eat in the post-Michael Pollan era?

A: Thanks for allowing your personal tragedy to alert others to this hazard. Losing a wanted pregnancy is a heartbreak. Losing one to a food-borne illness is especially tragic. Such illnesses should be preventable.

Food should be safe before it gets to you. That it sometimes is not is a consequence of our inadequate food safety system, which does not require food producers to test for harmful bacteria. The House of Representatives passed legislation that does so last summer, but the Senate is sitting on it. As an individual, you cannot easily protect yourself against invisible hazards in food. Congress must pass that legislation.

Without federal requirements, you are on your own to keep yourself and your unborn infant safe from food pathogens, especially Listeria. Much as I hate to add to what the French sociologist Claude Fischler calls “Listeria bacteria hysteria,” I must. Listeria preferentially affects pregnant women. If you are pregnant and want to stay pregnant, you must avoid Listeria.

This will not be easy. Listeria is widely dispersed in foods. Infections from it may be rare, but they are deadly. Listeria kills a shocking 25 percent of those it infects and is particularly lethal to fetuses.

Most people, including pregnant women, are immune to Listeria and do not feel ill when infected. But unlike most bacteria, Listeria penetrates the placenta, and fetuses have no immunity. The first sign of an infection can be a miscarriage or stillborn infant – too late for antibiotics.

How worried should pregnant women be about Listeria? Given our ineffective food safety system, I’d advise caution. The Centers for Disease Control and Prevention report 2,500 cases a year and 500 deaths. These numbers are minuscule – unless your pregnancy is affected.

Cases occur mainly among the young, the old and others with poor immunity. But the cause of miscarriages is not typically investigated, and I’m guessing that fetal deaths from Listeria are badly underreported.

Animals and people often excrete Listeria from their digestive tracts, even when they show no signs of illness. The bacteria get into food from infected animal waste and unwashed hands.

As a result, unpasteurized milk products and contaminated raw vegetables are frequent food sources. Other sources depend on yet another of Listeria’s nasty features – Listeria grows, reproduces and flourishes at refrigerator temperatures that stop other bacteria cold.

This explains why the CDC strongly advises pregnant women not to eat potentially undercooked foods stored in refrigerators: hot dogs, lunch meats, deli meats, patés, meat spreads and smoked seafood (salmon, trout, lox, jerky); soft cheeses such as feta, Brie, Camembert, those with blue veins, and especially Mexican “queso blanco fresco”; and raw milk or foods containing unpasteurized milk.

Even though some of these foods were cooked or pasteurized to begin with – blue cheese, for example – they can become contaminated after processing. Days or weeks of refrigeration give Listeria ample time to reproduce. Just about any food sitting around in a refrigerated package can be a source, with meat, fish and dairy foods especially suspect.

The CDC advises following safe food handling procedures to the letter at home. Avoid cross-contaminating raw and cooked foods, and use refrigerated perishables right away.

Listeria infections were virtually unknown 25 years ago, so view this hazard as collateral damage from the consolidation and centralization of our industrialized food supply.

Do not despair. There is some good news. Cooking kills Listeria. Pregnant women still have plenty of options for good things to eat that are safe.

Anything cooked hot is safe. So are hard cheeses, semisoft cheeses like mozzarella, pasteurized processed cheeses, and cream and cottage cheeses. These were cooked or are now too dry and salty for bacterial growth. Anything canned – patés, meat spreads, smoked fish, other fish – also is safe.

When it comes to food hazards during pregnancy, Listeria is unique. A sip of wine every now and then is not going to induce fetal alcohol syndrome, nor will your baby get mercury-induced brain damage from an occasional tuna sandwich. The risks from such hazards accumulate with amounts consumed over time.

But the risk from Listeria is acute. With so much at stake, and so many other food choices available, why take chances?

Just last month, the Food and Drug Administration reported recalls of queso fresco, blue cheese and bean sprouts because of possible Listeria risk. The FDA is doing its best, short of legislation. To keep Listeria out of the food supply, Congress needs to act. Write your representatives now.

Marion Nestle is the author of “Food Politics, “Safe Food” and “What to Eat,” and is a professor in the nutrition, food studies and public health department at New York University. E-mail her at food@sfchronicle.com and read her previous columns at sfgate.com/food.

I’ve had several requests to comment on the new New York City Board of Education restrictions on what foods parents can bring to school bake sales.  Home-baked goods are forbidden.  Instead, parents may bring fruits and vegetables (fine) or any of 27 commercial packaged snack foods (oops).

This ruling is an example of nutritionism in action – foods reduced to their content of a few selected nutrients.  The Board must think that if a food doesn’t have a Nutrition Facts label, it isn’t worth eating or its nutritional quality can’t be trusted.

This ruling is a perfect example of why we need standards for schools based on food, not nutrients.

Laura Shapiro explains the history of all this beautifully in an interview with the New York Times.

NPR also had plenty to say about parent protests.

If it were up to me, junk food would be out of schools altogether and bake sales and the like restricted to special occasions.  But if forced to choose between packaged snacks and home-baked cupcakes, I’d throw out the commercial snacks, and put some restrictions on the size and frequency of items at bake sales, but otherwise choose home-cooking every time.

I can hardly believe that Princeton sent out a press release yesterday announcing the results of this rat study.  The press release says: “Rats with access to high-fructose corn syrup gained significantly more weight than those with access to table sugar, even when their overall caloric intake was the same.”

How they came to these conclusions is beyond me. Here’s the original paper.

It has long been known that feeding sugars to rats makes them eat more and gain weight.  But, as summarized in Table 1 in the paper, the researchers did only two experiments that actually compared the effects of HFCS to sucrose on weight gain, and these gave inconsistent results.  Their other experiments compared HFCS to chow alone.

The study is extremely complicated and confusingly described.  As best as I can tell, here’s what they found:

1.  The first study used 10 male rats in each group and observed them for 8 weeks.  At the end of the study, the rats fed chow alone weighed 462 grams.  The rats fed sucrose plus chow weighed 477±9 grams.   The rats fed HFCS plus chow weighed 502±11 grams.   The authors say the difference between 477 and 502 grams is statistically significant.  But these rats were offered the sugars for 12 hours per day.  The rats fed HFCS for 24 hours per day, which should be expected to be fatter, were not.  They weighed less (470 grams) than the rats fed sucrose for 12 hours per day.  So these results are inconsistent.

2.  The second study did not compare rats eating HFCS to rats eating sucrose.  It just looked at the effects of HFCS in groups of 8 male rats.

3.  The third study used female rats (number not given) and observed them for 7 months.  At the end of the study period, female rats fed HFCS plus chow for 12 hours a day weighed 323±9 grams.  Female rats fed sucrose plus chow under the same conditions weighed 333±10 grams.   This result is not statistically significant.

Although the authors say calorie intake was the same, they do not report calories consumed nor do they discuss how they determined  that calorie intake was the same.  This is an important oversight because measuring the caloric intake of lab rats is notoriously difficult to do (they are messy).

So, I’m skeptical.  I don’t think the study produces convincing evidence of a difference between the effects of HFCS and sucrose on the body weight of rats.  I’m afraid I have to agree with the Corn Refiners on this one.

So does HFCS make rats fat?  Sure if you feed them too many calories altogether.  Sucrose will do that too.

NOTE 3/26: see point-by-point response to this post by Bart Hoebel, one of the authors of the study, in the Comments below.

Addition, November 23: Thanks to Jeff Walker, professor of Biology at the University of Southern Maine, Portland, for doing a detailed critique of the study, most thoughtful and well worth a look.

The impossibly impenetrable health care bill that just passed the House has one little piece of good news buried in it: national calorie labeling.

The provision covers chains with 20 outlets throughout the country and is supposed to go into effect in a year or so.  It also covers vending machines!  These are great steps.  Calorie labeling has two effects.  It educates anyone who is interested to look and think about it.  And it encourages chain restaurants to offer lower calorie options.  See note below giving the index to this section.

Cheers to Center for Science in the Public Interest, which has lobbied for years to get this into law.

Note:  Thanks to Ellen Fried for sending me this link to an Index to the menu labeling provision.

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.

The USDA’s Office of the Inspector General (OIG) issued a report last week criticizing the agency’s oversight of the National Organic Program (NOP). The OIG said the USDA had followed some of the recommendations in its previous report (in 2005), but by no means all.

This report is a sharp critique of the last administration’s ambiguous enforcement of organic standards.  This new administration recruited Kathleen Merrigan to get the program back in shape and the agency says it is totally committed to doing so.

But the administrator of the program responded to the OIG audit with this comment: “The integrity of the organic label depends largely upon effective enforcement and oversight of the many accredited certifying agents responsible for reviewing organic operations.”

Largely?  I would say entirely.

USDA is an uncomfortable home for organics because its main goal is to support industrial agriculture.  For years, the NOP home page carried a statement that organic foods were not better than industrial foods.  I am happy to see that the statement is no longer there, but I’m guessing some old attitudes still remain.

USDA delegates organic oversight to certified inspection agencies.  These vary in diligence.  I constantly hear suspicions of fraud in the organic enterprise.  USDA needs to do everything it can to put those suspicions to rest.

Otherwise, why pay more for organic foods?

Dear new foodists (I do love the term – see previous post): For some light entertainment over the weekend, try this short cartoon. A sommelier has a conversation with his wife on an otherwise empty New York subway.  Thanks to Rob Kaufelt of Murray’s Cheese for sending.

Food companies interested in doing something meaningful to prevent childhood obesity are in a bind.  Preventing obesity usually means staying active; eating real, not processed, foods; and reserving soft drinks and juice drinks for special occasions.  None of this is good for the processed food business.  At best, food and beverage companies can make their products a bit less junky and back off from marketing to children.  In return, they can use the small changes they make for marketing purposes.

Perhaps as a result of Michelle Obama’s campaign (see yesterday’s post), companies are falling all over themselves – and with much fanfare – to tweak their products.

GROCERY MANUFACTURERS ASSOCIATION (GMA):  By all reports, GMA members applauded Mrs. Obama’s remarks.  GMA says its member companies are already doing what she asked.

Parke Wilde, a professor at the Tufts School of Nutrition (and food policy blogger), gave a talk at that meeting in a session dismissingly titled,  “The New Foodism.”  His comment:

I enjoyed hearing Michelle Obama’s talk, which was well written and delivered and fairly forceful in places. In my afternoon panel, I said grocery manufacturers would find some threatening themes in books and documentaries promoting local and organic and sustainable food, but that there is also much of substance and value. Then, Susan Borra [Edelman Public Relations] and Sally Squires [Powell Tate Public Relations] in the next session said that grocery manufacturers are frequent subjects of unfair criticism and have nothing to apologize for.

Take that, you new foodists!

MARS must think it knows more than the FDA about how to label food packages.  It is developing its own version of front-of-package labels. It volunteered to put calories on the front of its candies; its multi-pack candies ay 210 calories per serving on the front.  That number, however, remains on the back of the small candy store packs.  Mars’ new labeling plans use the complex scheme used in Europe.  I’m guessing this is a bold attempt to head off what it thinks the FDA might do – traffic lights.

KRAFT announces that it is voluntarily reducing the sodium in its foods by 10% by 2012.  Kraft’s Macaroni & Cheese (SpongeBob package) has 580 mg sodium per serving and there are two servings in one of those small boxes: 1160 in total.  A 10% reduction will bring it down to 1050 mg within two years.  The upper recommended limit for an adult is 2300 mg/day.

PEPSICO announced “a voluntary policy to stop sales of full-sugar soft drinks to primary and secondary schools worldwide by 2012.”  In a press statement, the Yale Rudd Center quotes Kelly Brownell saying that “tobacco companies were notorious for counteracting declining sales in the U.S. with exploitation of markets elsewhere, particularly in developing countries:”

it will be important to monitor whether the mere presence of beverage companies in schools increases demand for sugared beverages through branding, even if full-sugar beverages themselves are unavailable…This appears to be a good faith effort from a progressive company and I hope other beverage companies follow their lead…this announcement definitely represents progress [Note: see clarification at end of post].

According to PepsiCo, this new policy brings its international actions in line with what it is already doing in the U.S.  The policy itself is voluntary, uses words like “encourage,” assures schools that the company is not telling them what to do, and won’t be fully implemented until 2010.  It keeps vending machines in schools and still allows for plenty of branded sugary drinks: Gatorade, juice drinks, and sweetened milk for example.

Could any of this have anything to do with Kelly Brownell’s forceful endorsement of soda taxes?

LOBBYING: The Center for Responsive Politics says food companies spent big money on lobbying last year, and notes an enormous increase in the amount spent by the American Beverage Association (soda taxes, anyone?).  For example:

How to view all this?  I see the company promises as useful first steps.  But how about the basic philosophical question we “new foodists” love to ask: “is a better-for-you junk food a good choice?”

OK.  We have the Public Relations.  Now let’s see what these companies really will do.

Addendum: I received a note clarifying Kelly Brownell’s role in the PepsiCo press release from Rebecca Gertsmark Oren,Communications Director,The Rudd Center for Food Policy and Obesity,Yale University:

The Rudd Center did not work with PepsiCo on their initiative to stop sales of full-sugar beverages in schools worldwide, nor did we jointly issue a press release. A statement released by Kelly Brownell in response to PepsiCo’s announcement was simply intended to commend what appears to be a step in the right direction. As Kelly’s statement also mentioned, there is still plenty of work to be done. It’s also worth noting that the Rudd Center does not take funding from industry.