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Sunday, May 16, 2010

Chocolate as an Iron Source

A patient of mine sent me a link to an article on the iron content of dark chocolate, indicating that chocolate has more iron than the same amount of beef , and wondering why he didn't know this and why it didn't receive more publicity.

It is true that gram for gram, dark chocolate has more iron than beef. However, I wouldn't recommend that you try to get your recommended daily iron intake from chocolate. For most of us, neither chocolate nor beef is the best way to get iron. Here's why.

The first problem is that a healthy serving size of chocolate is only about 7.5 gm. Organic dark chocolate tasting squares by Dagoba are 9 gm; Giardhelli's dark chocolate squares are about 17 gm each. According to the USDA nutrient analysis website, 7.5 grams has 45 calories, 3 grams of fat, and 2 grams of saturated fat and less than 0.89 mg of non-heme iron, or about 4% of the recommended daily allowance.

While I hesitate to say that any serving size of beef is "healthy", a 6 oz serving (185 grams) containing 40 gm of protein is 185 gm. This is 25 times the weight of the healthy serving of chocolate. 185 gm of beef (6 ounces) has 4.35 mg of iron. If you ate enough chocolate to have 4.35 mg of iron, you'd be eating 37 gm of chocolate, which would have 220 calories, with 15 gm of fat (10 of saturated fat). This would be a similar amount of iron, and also of fat and saturated fat as the beef, but with none of the protein. To eat the daily recommended allowance of iron for men and adult women after menopause (8 mg) as chocolate, we would need to eat 67 grams of chocolate, adding 405 calories, 27 grams of fat (and 18 gm saturated fat) to our diet. So, chocolate is not the best way to acquire iron, because it comes at the cost of too many fat, especially saturated fat and sugar calories. While beef has unhealthy fat too, at least it contains a good protein portion while getting those calorie and does not contain sugars.

I would recommend sticking to 7.5-10 grams of chocolate daily, and aiming to get most of our iron intake from vegetables. Getting a little extra iron from the chocolate is just a bonus.

Another reason why chocolate is not as good an iron source is that iron in chocolate is not absorbed as well as the iron in beef. Chocolate has the non-heme form of iron, which is less well absorbed than the heme variety. Beef has both heme and non-heme in about a 60/40 ratio. So, if we avoid beef for health or other reasons, we need to aim for around twice the daily value of iron that is suggested for those who are primarily eating their iron in beef.

The FDA fact sheet on iron lists the recommended daily intake of iron as 8 mg for adult women after menopause and men, and as 18 mg for adult women prior to menopause. It does not distinguish whether the iron is in the heme or non-heme form in this recommendation. The Vegetarian Resource Group has provided recommended allowances for those who will be eating iron mostly or only in the non-heme form, and suggests aiming for 14 mg daily of non-heme iron for women after menopause and men, and 33 mg daily for adult women prior to menopause.

Ascorbic acid (Vitamin C) improves non-heme iron absorption. Therefore, to get the most iron possible from one's dark chocolate square, I would suggest that you eat it with a healthy Vitamin C (ascorbic acid) - containing food, such as dried apricots or mandarin orange slices. As Michelle Francl in her "Culture of Chemistry" blog as noted, dried apricots (try to get the unsulphured kind) dipped in dark chocolate are a wonderful combination. I am also partial to clementine or mandarin orange sections dipped in dark chocolate.

Tea and coffee inhibit iron absorption due to the tannins they contain. Black tea is worse than coffee in this regard, but both are inhibitory. Therefore, it is better to drink tea and coffee between meals or well before an iron-rich meal than to have tea or coffee with or right after such a meal. For the same reason, a chocolate-covered espresso bean is probably not a good idea as an iron source, nor mixed chocolate and coffee mocha drinks. Instead drink herbal teas such as lemon tea which are rich in ascorbic acid.

Studies vary in what they find about the effects of calcium on iron absorption. Many nutritionists advise to avoid dairy products and calcium supplements around the time of iron consumption. However, some studies have shown that calcium does not inhibit non-heme iron absorption. Although there is controversy, it seems safer not to count on much of a boost in iron intake from milk chocolate, or traditional hot chocolates or hot cocoa made with milk solids.

Some plants also have large concentrations of phytates and polyphenols (of which the tannins are one type) which inhibit iron absorption. Therefore, plants like soybeans and spinach have a lot of iron, but the iron is poorly absorbed if they are eaten alone. This effect is ameliorated by Vitamin C, so the best solution is to make sure that beyond the amount you get in your one to two small squares of dark chocolate, you eat your iron-containing plants (spinach, broccoli, cauliflower,bok choy etc.) along with foods containing Vitamin C, such as sweet red peppers, oranges, lemons, limes, guavas, and lichis. Note that broccoli, cauliflower, and brussel sprouts are good sources of both iron and Vitamin C, making them excellent sources of dietary iron. Herbs such as thyme, parsley, and dill also have a lot of Vitamin C, and so can be added to the iron-rich vegetables which lack vitamin C.

If you avoid beef and you eat a lot of vegetables such as spinach, bok choy, broccoli, and cauliflower, you will probably ingest enough non-heme iron naturally. This can be augmented by combining vegetables with ascorbic acid containing foods listed above.

In summary, I would not recommend increasing your consumption beyond a small square or two of dark chocolate per day in order to attempt to increase iron consumption, and would recommend eating the dark chocolate with foods containing vitamin C, while avoiding regular tea, coffee or dairy products together with it. If you do drink regular tea, drink a lemon tea or add lemon to it, which will reduce the inhibitory effects of tannins on the iron absorption.

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