You might think by looking at the chart above that chromium is a mineral mostly missing in the food supply. However, it would definitely be wrong to draw this conclusion. Chromium is provided by every food group—including vegetables, fruits, grains, legumes, nuts/seeds, seafood, meats and dairy—so it is definitely not a missing mineral in our foods. However, chromium is present in many foods in very small amounts (1-2 micrograms or less). In fact, our rating system only calculated one excellent source of chromium. So we think about this mineral as one that you obtain by eating an overall healthy diet rather than any specific foods. It's also important to note that the chromium content of food has been inadequately measured by food scientists. Research journals typically show less than 10 total measurements for chromium in any particular food, and many of these measurements show little consistency. As a result, we know that many foods contain small amounts of chromium, but we are still not sure about exact amounts or how amounts might vary under different circumstances. Once again, these factors shift the focus onto an overall healthy diet when evaluating intake of chromium.
Foods rich in chromium, specifically brewer's yeast, have been used to help balance blood sugar since the time of the Civil War. In the 1950s, researchers discovered the role of chromium in blood sugar control, a role we describe below in the Role in Health Support section.
Among the foods where the chromium content is noted, we have broccoli listed as an excellent source. We also list six foods as good sources. These foods are barley, oats, green beans, tomatoes, romaine lettuce, and black pepper.
While we don't know the exact chromium content of many of the World's Healthiest Foods, it appears that our strategy of eating—based around minimally processed and plant-rich meals with liberal use of spices—would be expected to ensure a consistent supply of this mineral.
A key role for chromium in the body is related to control of blood sugar. There is a signal molecule called low-molecular weight chromium binding substance (LMWCr) involved in blood sugar control. (You may also hear this molecule being referred to as chromodulin.) Although it has a long name, LMWCr it is a tiny molecule, built from just a few amino acids.
This LMWCr binds next to the place where insulin, a key hormone that controls blood sugar, interacts with the outside of a cell. Its role is to increase the strength of the signal that insulin sends, helping to drive blood sugar into cells more quickly after a meal. (It is also worth noting here that LMWCr is a very specifically defined molecule with a specifically defined metabolic role. Prior to discovery of LMWCr, a much less clearly defined molecule called glucose tolerance factor, or GTF, had been the subject of much interest in nutrition and was typically thought to involve a combination of chromium, vitamin B3, and select amino acids. However, unlike LMWCr, GTF remains to be specifically defined or universally accepted by researchers.)
We have seen evidence of chromium deficiency leading to abnormally high blood sugar as well as evidence that restoring chromium supply back toward normal or higher can enhance blood sugar control even in some people with diabetes. Research studies of this kind underscore the importance of LMWCr and chromium for blood sugar balance.
Healthy diets like the World's Healthiest Foods eating plan tend to be associated with low risk for type 2 diabetes. Strong chromium nutrition is one of many reasons this would be true.
Note that some of our chromium-rich World's Healthiest Foods have additional ways that they help balance blood sugar. Cinnamon and sweet potatoes would be a couple examples of these. Here's a tasty recipe—Sweet Potatoes with Ginger and Cinnamon—that combines them.
Because the amounts of chromium in foods are quite small, researchers have struggled to clearly quantify dietary chromium intake in the same way we can with other nutrients. However, based on our overall understanding of food and nutrients, we are confident that many of the World's Healthiest Foods contain chromium, even if the database we use to determine content is incomplete. Broccoli, which does have a measured value for chromium in our database, contains about half of your daily requirement per serving and ranks as an excellent source of this nutrient. In the vegetable group, tomatoes, green beans, and romaine lettuce rank as good sources.
Several whole grains, including oats and barley, rank as good sources of chromium in our rating system. Other clearly-established food sources of chromium (but not ranked in our system as good, very good, or excellent sources) include fruits like apples and bananas, meats like chicken, grains like brown rice, and dairy products like eggs and cow's milk. Herbs and spices also provide measurable amounts of chromium, with black pepper ranking as a good source in our rating system. As described earlier, we are confident that many foods in addition to the ones listed above contain very small-to-small amounts of chromium.
To summarize your best food options for increasing chromium in your meal plan: while we only show 7 WHFoods as being ranked sources of chromium, and while only 11 additional WHFoods show actual microgram amounts for chromium, we are confident that you will be getting chromium from whole, natural foods in all food groups, as well as in herbs and spices. When trying to increase your chromium intake, it's important to take a broad approach involving an overall healthy diet.
|World's Healthiest Foods ranked as quality sources of|
|Green Beans||1 cup||43.8||2.04||6||2.4||good|
|Romaine Lettuce||2 cups||16.0||1.25||4||4.0||good|
|Black Pepper||2 tsp||14.6||0.93||3||3.3||good|
Density>=7.6 AND DRI/DV>=10%
Density>=3.4 AND DRI/DV>=5%
Density>=1.5 AND DRI/DV>=2.5%
Researchers have looked at the chromium content of prepared and convenience foods, and the amount of chromium loss varies substantially with the type of food and the type of processing. There do appear to be some patterns, though.
Turning a whole grain into a refined one appears to result in a large percentage reduction in chromium content. For example, a serving of white bread contains about half the chromium of an equivalent amount of whole-wheat bread.
Cooking vegetables, at least lightly boiling or steaming them, does not appear to deplete excessive amounts of chromium. We've seen studies showing loss of approximately 5-30% chromium from vegetables cooked in this way.
We don't yet know if there is a true deficiency state of chromium, or if there is at what intake level it would emerge. Also, limitations in the ability to measure chromium in human tissues as well as food make it difficult to study large populations.
We do believe, however, that chromium levels vary with age, with levels going down by up to 40% in older versus younger people. This drop is probably related to dietary intake, as other research groups have concluded that chromium intake in older persons is frequently below recommended amounts.
People who eat highly refined diets, especially ones rich in simple sugars, also may be at risk of deficient chromium intake. In other words, their diet choices might leave them consuming too little chromium. One research group has also suggested that these same sugar-laden diets increase the rate of chromium loss from the body, exacerbating the deficiency risk. Given the central role of chromium in blood sugar control, this two-pronged attack on chromium status is another good reason to avoid routine intake of processed, refined foods that are also high in simple sugars.
The importance of diet quality to chromium levels is also supported by a 2011 study in which a research group taught a group of 169 overweight or prediabetic adults to eat a healthier diet—one that included more fruits, vegetables, and complex carbs than they were used to eating. In response to the healthier meal plan, blood chromium levels went up significantly from where they started.
Once again, we do not have as much information as we would like in this area. But we do have bits and pieces of information from some specialized areas. People on prolonged intravenous nutrition often develop diabetes. There are many reasons this is true, but one potential reason is chromium deficiency. For these people, getting chromium levels back to normal can reverse the issue.
Heavy exercise can increase the rate of chromium loss in the urine. Whether this is detrimental or could exacerbate deficiency of this nutrient has not been determined.
Vitamin C enhances the absorption of dietary chromium. For instance, women absorbed more chromium from a supplement when they were simultaneously given 100 mg of vitamin C—about the same amount you'd find in a serving of chromium-rich broccoli. While we believe this supplement study was very helpful for understanding the relationship between chromium and vitamin C, getting both nutrients from a whole, natural food is definitely the approach we recommend.
Chromium and iron can be transported on the same protein (transferrin) in the blood stream. It is plausible that too much of either of these minerals could impair metabolism of the other. But this interaction has never been demonstrated to be a problem in humans.
Toxicity from dietary chromium has not been reported, and not very likely to occur. Studies where researchers use chromium like a drug—at doses close to 50 times more than seen with average diets—did not lead to significant risk of adverse effects.
In stark contrast to food intake and diets, there are industrial workplace settings where risk of excessive chromium exposure (in the form of hexavalent chromium, or chromium-6) can be significant. At the top of the list for higher-risk chromium exposure are welding, painting, electroplating, steel and iron manufacture, and textile dyeing. Especially in regions where the above manufacturing facilities are located (including numerous urban locations throughout the U.S.), water supplies can at greater risk for accumulation of chromium. Municipal water supplies are currently monitored by the U.S. Environmental Protection Agency (EPA) to ensure maximum chromium levels in water of 100 parts per billion (ppb) or less. If you are concerned about possible exposure to excess chromium in your drinking water, you may want to consider purchase of a home water filter certified for reduction of hexavalent chromium, or the purchase of bottled drinking water from a manufacturer who provides you with information about chromium content.
In 2001, the National Academy of Sciences published Dietary Reference Intakes (DRI) for chromium. These DRI recommendations came in the form of Adequate Intake (AI) levels as follows:
The NAS did not set a Tolerable Upper Intake Level (UL) for chromium.
The Daily Value (DV) for chromium is 120 micrograms (mcg) per 2000 calories. This DV target is used on food labels.
At WHFoods, we adopted the chromium DRI for 14-50 year-old males, since that level was the highest recommended intake amount for any age-gender group (except women who are breastfeeding). This DRI and our WHFoods recommended daily intake level is 35 micrograms.