Later on, I recalled having hundreds of similar Iceberg-knocking conversations with resort guests. Then a light bulb went off... I realized that I had “bought into” a common belief without ever seeing any data. It was time for a reality check. Is Iceberg lettuce genuinely inferior (nutritionally) to other lettuce varieties, or could it have some redeeming value for health–conscious consumers? To put the issue to rest, I reviewed the USDA’s National Nutrient Database for Standard Reference, Release 15 (http://www.nal.usda.gov/fnic/foodcomp/Data/index.html). I have reformatted this information into a format that can be downloaded here. For the sake of relativity, recommended minimum daily intakes are included, where available (National Academy of Sciences, Daily Values). So. . . at the risk of being embarrassingly contraindicated by some sharp statistical analyses, let’s compare reported averages for several lettuce nutrients.

Nutrient Comparisons

Calories/Caloric Sources
The dozen or so calories inherent to 2 cups of lettuce never raises eyebrows. Theoretically, with everything else remaining equal, consuming a huge Iceberg garden salad daily for a year would result in ½ pound less body weight than our identical twin who opted for leaf lettuce. Since we do not live in a theoretical world, I’m inclined to dismiss the energy issue as a potential waste of precious scientific hot air.

However, a point can be made for the protein issue. It's been my experience that many consumers believe produce to be protein-free. Not so. According to SR15, lettuce has approximately 1 to 1-1/2 grams, depending on the type. Granted, it is small. However, the sum total of the protein derived from plant foods in a healthier diet may contribute 1/3 to 1/2 of our total protein requirement. Don't write off the fruits and veggies as insignificant protein sources. Gorillas, rhinos, horses - all herbivores - never seem to be lacking in muscle mass.

Phytosterols
Phytosterols reduce the risk of several diseases, especially cancer. According to our table, Looseleaf lettuce has almost 4 times as many phytosterols as Iceberg. Let's hear it for the Simpsons!

Fiber
The average person in this country consumes 11 grams of fiber per day. Responsible organizations like the AHA, ADA, and the US government recommend more – about 30 grams per day. Guests at Red Mountain normally consume 35-45 grams/day in approximately 1500 calories. Since fiber is inherent only to foods of the plant kingdom, all dietary veggies, like lettuce, have to be regarded as team players. In our comparison, Iceberg lettuce fared mediocre, ranking second lowest in fiber. Only Butterhead had less. The case for not buying Iceberg is evolving.

Vitamins
Iceberg bombed in vitamin A and C content – normally lucrative in most greens. It also ranked last in thiamine, riboflavin, niacin, pantothenic acid, B-6, and E. Only in folate (vitamin Bc), did it emerge from the cellar to rank second to lowest. There is no data for vitamins D and K.

Minerals
Iceberg continues to maintain its reputation as a low-nutrition, fiber-water bulking agent when comparing mineral content. For ash, a reflection of total minerals, Iceberg, once again ranked last. Specifically, it ranked last in calcium, phosphorous, and potassium; second to last in copper, iron, magnesium, manganese, and zinc; tied for first in selenium (4-way) and sodium (2-way). As indicated on the table, there are no analyses reported for chromium, iodine, or molybdenum.

Essential Amino Acids
There are 9 essential amino acids required for adults: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Although very low (and possibly non-significant), Iceberg lettuce ranked dead last in all 9 amino acids. In addition, Iceberg had the lowest level of tyrosine – a non-essential amino acid used by the body to synthesize thyroxine.

Essential Fatty Acids
Linoleic, linolenic, and arachidonic acids are necessary for maintaining healthy cell walls, normal cholesterol metabolism, and adequate levels of prostaglandins – body regulators of blood pressure, blood coagulation, and other functions. They are said to be essential. Among our lettuce competitors, Iceberg again demonstrated its Mets-like character (forgive me Mets fans) and ranked last in linoleic and linolenic acids. According to the chart, no data has been reported for arachidonic acid.

Omega-3 fat, normally thought to be in fish or produced from flaxseed oil, is in lettuce, albeit in small amounts (the smallest reported amount being in Iceberg).

Conclusions

We were right - forget Iceberg. In this evaluation, we compared statistically derived averages; and, it is possible (for some nutrients) there may not be any significant differences between some or all reported means. However, having glanced at a few reported standard deviations, I’m convinced that Iceberg has not been given a bum rap. It is inferior in nutrient content – avoid.

Butterhead in many instances approached the cellar in nutrient composition and lacked the overall track record required for a genuine salad bowl champion. To the contrary, Romaine and leaf type lettuces were much more impressive.

Bottom line: Buy Romaine (Cos) or Looseleaf lettuce; leave the head types in the produce department.

[ click here to download a PDF of the Lettuce Comparison chart ]

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