When Vitamin C-ing is Disbelieving

This is a guest blog post by Carol Harvey, Director of food/nutrition labeling and product development at Palate Works.

There’s something about numbers in table format – they look so official, so accurate. But nutrition data, because of the nature of food itself, is inherently inaccurate. Foods vary in nutrition based on ripeness/season, conditions/time in transport or storage, the method and time cooked or processed, varying sizes and densities of harvested foods, inexact measuring/portioning by humans and machines, etc. Then there are the much bigger data breaches that come from human error and ignorance, and these can go unnoticed for years.

Vitamin C is one of the nutrients frequently over- (and occasionally under-) reported, even by seemingly reputable sources (e.g., USDA, large food companies, etc.).  Anyone familiar with the chemistry of vitamin C (ascorbic acid) knows why. It’s unstable in a variety of environments – water, air, heat, alkali – i.e., most of the things that are done to food (including what you might do with it at home) during processing, storage and/or heating before eating.

The following are just a few of the many examples of bad C data that can be found on store shelves and in the USDA database (which is then uploaded by nutrition software programs, apps, etc.).

Planters Nut-rition Antioxidant Mix

-       Contains:  almonds, sugar, dried banana, dried peaches, cashews, dried blueberries, vegetable oil, dried cranberries, citric acid, natural flavor

-       Label shows 10% of Daily Value (DV) for vitamin C (that’s the minimum required to make a “good source” claim or antioxidant claim).

-       Our lab test showed only 4% of DV for vitamin C (even for the 32-gram serving size shown on the label, vs. FDA’s 28-g standard for such a snack). This is not surprising, because most of the vitamin C in fresh produce is lost during drying, and dried fruit is barely half of the product, anyway. (We’re guessing the product has some undeclared ascorbic acid added for its preservative effects, because it’s unlikely the dried fruit would provide any vitamin C.)

Navitas Dried Mulberries

-       Contains:  dried mulberries (not freeze-dried)

-       Label shows 130% DV for vitamin C (impossible for air-dried whole fruit).

-       Our lab test showed 9% DV (rounds up to 10%, so they could get away with calling it a “good source,” but definitely not an “excellent source,” and far from 130% DV).

-       This is probably an example of someone using the easily-available data for raw berries, rather than paying for a lab test of the dried fruit… and not realizing there is a BIG difference.

Acai Roots Acai Powder

-       Contains:  freeze-dried acai berry

-       Label shows 15% DV for vitamin C.

-       Fresh acai does not have much vitamin C, so freeze-dried definitely will not be a good source.

-       Even Navitas’ Freeze-Dried Acai Powder shows 0% DV for C (although they make unsupported claims that the powder is a good source of antioxidants and amino acids).

Trader Joe’s Dried, Sweetened Kiwi

-       Contains:  dried kiwifruit and sugar

-       Label shows 50% DV for vitamin C (which would be more than an “excellent source”)

-       Again, air-dried fruit loses most of its vitamin C; 50% is impossible… actual is probably 0% DV. Someone was probably using data for fresh kiwi.

Smart Juice Pear Juice


-       Contains:  organic pear juice (web site says “nothing added”)

-       Label shows 100% DV for vitamin C.

-       Pears (like apples) don’t contain much vitamin C, even when fresh, and after processing (all packaged juices have to be at least flash pasteurized to be made safe for even a refrigerated shelf life of one week, and this product is bottled for much longer/non-refrigerated storage) there would be none = 0 vitamin C.

-       This company has labeling problems galore. Some of the tip-offs to bad data are the rounding violations (e.g., stating sodium data and %DVs with a decimal point), the customer testimonials with “cure” claims, and fiber content above 0 (by definition, a “pressed” juice has the fiber removed, so none of the juices should show any, but most of them do).

Trader Joe’s Steamer Clams

-       Contains:  clams, butter, garlic, modified corn starch, natural butter flavor, lemon, parsley, citric acid, spices

-       Label shows 10% DV for vitamin C (this would make it a “good source”) in 33 g cooked clam meat.

-       The tiny amount of “lemon” in here is the only ingredient that “might” provide vitamin C (at least until cooked). Turns out the error comes from USDA’s steamed clam data, which the manufacturer of this product evidently used for their nutrition analysis. Clams (especially after cooking) have no appreciable vitamin C, but the USDA database shows 22 mg (25% DV for vitamin C) in 100 g of steamed clams, and 10 mg in 100 g of breaded/fried clamsbut they show 0 vitamin C in any amount of raw clams! You can’t ADD vitamin C by cooking something (the opposite would happen).

-       Meanwhile, if you go online and search for “steamed clams” or clam chowder you will find this error copied pretty much everywhere, except by companies, such as Campbell’s, that do their own lab testing.

Trader Joe’s Gluten-free 3 Cheese Pizza with fresh Roma tomatoes

-       This is an example of a frozen product that you obviously wouldn’t eat as-is, out of the box without cooking, but the nutrition data is for just that – the raw, uncooked ingredients.

-       Label shows 15% DV for vitamin C.

-       Because there are fresh tomatoes on the pizza, it contains vitamin C, or at least until cooked. At that point, the vitamin C is close to 0.

-       Nutrition Facts data is often for the uncooked product; after cooking, the nutrition for certain nutrients (especially vitamin C) will be much lower… or 0.

How to “C” the above information:

Don’t look to processed/cooked foods to provide your vitamin C. Unless it has been added in a stable form, it isn’t there in any significant amount, even if the label shows it (a rare exception is when the source is a freeze-dried fruit/berry). The best sources are fresh fruits and vegetables in season:  strawberries, mangoes, citrus, papaya, kiwi, broccoli, bell/chili peppers, etc.

Next up: Foods with under-reported nutrients (yes, that happens too).

Carol Harvey has been a nutrition labeling and product development consultant for over 15 years. She can be reached at palatemail [AT] yahoo [DOT] com.

Get Fooducated

  • Brookell14

    I’m not positive how I feel about this article. I went to school for nutrition and I was taught that clams are a good source of of Vitamin C.. Also it’s stated on every reputable site I know. Leaves me a bit confused!

    • Carol H.

      Raw mollusks do contain some vitamin C, but after cooking… no. And you probably do not want to eat raw clams. This is why the data in the USDA database cannot be correct. It should show some C in raw clams, but not in the cooked versions. It can’t be the other way around… physically/chemically impossible. There are and have been other errors in large databases (not to mention the thousands of errors on individual product labels) — it is best to not assume they are always correct, especially when the math/logic do not add up.

  • michealjohn

    The
    resource that you mentioned here is something that I have been looking from
    quite a time. And finally it ended with such a nice blog post. Don’t have words
    to thank you.