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J A N U A R Y 1 , 2 0 0 6 / A N A LY T I C A L C H E M I S T R Y 7

U.S. food manufacturers are now re-quired to list on the Nutrition Factslabel how much trans fat is in theirproducts. In preparation for the newrule, which went into effect January 1,food manufacturers began altering theiringredients to cut down on the biggestsource of trans fatty acids—partially hy-drogenated oils. Various crackers, cook-ies, and other products containing re-duced amounts of these artery-cloggingoils began showing up in the marketwith labels claiming 0 g trans fat. But,as any analytical chemist knows, fewthings are ever really zero; they are usu-ally only below the detection limit.

In the case of trans fat, if the level is<0.5 g/serving, the label will read 0 gtrans fat. Some argue that this new transfat label is misleading. By reducing theserving size, manufacturers can make itappear as though their products containno trans fat, when in fact, they do. Sayyou eat 3 servings of a product thatcontains 0.4 g trans fat/serving. That’s1.2 g of trans fat you are consuming.But because the amount per serving is<0.5 g, the label reads 0 g.

So why did the U.S. Food and DrugAdministration (FDA) set the reportinglevel at >0.5 g trans fat/serving? Couldthe amount of trans fat be listed to thenearest tenth or hundredth of a graminstead of the nearest 0.5 g? The answerdepends on the analytical method that isused.

FDA does not require laboratories touse one particular analytical method fornutrition labeling purposes. The agencydoes, however, require that an “appro-priate” method be used. For the analysisof trans fat, FDA has approved both IRand GC methods, including an IRmethod of the American Oil ChemistsSociety and a GC method of the Associ-ation of Official Analytical Chemists In-ternational. The detection limits of theIR method are much higher than thoseof the GC method.

In its final ruling, FDA decided thattrans fat will be reported to the nearest

0.5 g increment below 5 g and to thenearest gram increment above 5 g, be-cause anything <0.5 g “will pose a

problem for laboratories that are set upto quantify trans fatty acids by IR” (Fed.Regist. 2003, 68, 41,434–41,506). Al-though GC is sensitive enough to detectlevels <0.5 g, the analysis is slower thanIR and requires more sample prepara-tion. Many laboratories continue to useIR for trans fat analysis because of itshigh throughput.

One of the problems with IR, how-ever, is that it tends to overestimatetrans fat levels, particularly at lower lev-els. In addition, IR can’t separate andidentify specific trans fatty acids. GC,however, can be used to quantify thedifferent trans fatty acids, provided along enough column is used. Laborato-ries can use either method for the analy-sis of trans fat, but they must report thelevels to the nearest 0.5 g.

So the next time you reach for thatbox of crackers or other snack foods,make sure to read the list of ingredients.If it contains partially hydrogenated oil,it contains trans fat, regardless of whatit says on the Nutrition Facts label. a

—Britt Erickson

Trans fat free—is it really?

Beginning this month, food manufacturersare required to list the amount of trans fat intheir products to the nearest 0.5 g.

GOVERNMENT AND SOCIETY

A consortium of >200 researchers from around the world has published phase one of the

HapMap, a comprehensive catalog of patterns of genetic variants in human DNA sam-

ples (Nature 2005, 437, 1299). The goal is to eventually correlate these genetic variants

with common diseases.

The idea of a HapMap project started forming after the completion of the human

genome sequence in 2001 and a massive effort to characterize single nucleotide poly-

morphisms (SNPs) across the genome. These initial data allowed scientists to recognize

the haplotype structure of the human genome and led to the formation of the Internation-

al HapMap Consortium.

The HapMap project has spurred significant advances in technology for testing ge-

netic variations. When the project began in 2002, “determining the genotype of a SNP in

a patient cost nearly a dollar, and we could do hundreds a day. Today, the prices have

dropped in many cases to a fraction of a penny per genotype, and we can do millions a

day,” says Stacy Gabriel of the Broad Institute.

Phase I HapMap contains >1 million SNPs. The consortium is nearing completion of

the second phase, which will contain nearly 3� more SNPs than the first.

First map of human genetic variation

Nutrition FactsServing Size 1 cup (228g)Servings per Container 2

Amount per Serving

Calories 250 Calories from Fat 110

% Daily Value*

Total Fat 12g 18%

Saturated Fat 3g 15%

Trans Fat 3g

Cholesterol 30mg 10%

Sodium 470mg 20%

Total Carbohydrate 31g 10%

Dietary Fiber 0g 0%

Sugars 5g

Protein 5g

Vitamin A 4%