Chromium in Diabetes:
The Controversy Continues
Many years of controversy continue regarding supplemental chromium in the treatment of diabetes. Chromium is widely available as a nutritional supplement in a wide number of forms and recently the Food and Drug Administration (FDA) approved a qualified nutritional claim regarding the health benefits of chromium. Clinical research has been conflicting about its value in the treatment of diabetes - some studies showing benefit while others do not. So what is a person with diabetes to do? Should I take it? What form is best? Is there any danger of taking chromium? What is the best dose? I hope this article will provide some background offering some perspective on why the chromium controversy continues.
Chromium: An Essential Nutrient
Chromium is an essential mineral for human nutrition and aids in the normal function of insulin...
Chromium is an essential mineral for human nutrition and aids in the normal function of insulin - one hormone that is critical for the normal regulation of blood sugar. The essentiality of chromium was discovered by mistake - individuals who were in the hospital receiving liquid nutrition were developing diabetes. When chromium was added to the nutrition packs (total parenteral nutrition or TPN), diabetes was prevented.
Following this discovery, several nutrition researchers began trying to understand how chromium functions in our cells. Eventually an elaborate model was pieced together that seems to explain the function of chromium and its role in blood sugar regulation; in brief, chromium is stored inside of our cells bound to a small protein, when insulin binds its receptor chromium assists in the insulin message and then is excreted from the cell and ultimately from the body (Vincent et al. 2000). This process seems to occur in a glucose-dependent manner, i.e. higher sugar = greater insulin-binding (assuming normal function) = more chromium losses.
Nutritional Requirements for Chromium
... people with diabetes have lower blood chromium levels and also excrete more chromium in their urine than do people without diabetes.
According to the Food and Nutrition Board, the Adequate Intake (AI) for chromium for adult women is 20-25 mcg per day and for adult men is 30-35 mcg per day. However, as stated above, chromium excretion is directly related to how high the blood sugar is (and how much insulin binding occurs) suggesting that chromium intake for someone with diabetes - i.e. with chronically elevated blood sugar - may in fact be greater than the current AI. This is supported by research findings that showed people with diabetes have lower blood chromium levels and also excrete more chromium in their urine than do people without diabetes (Anderson et al. 1990).
Unfortunately the AI is based on the chromium requirements for people without diabetes. Not enough research has been performed on people with diabetes to demonstrate an optimal dose. Similarly, research has not been performed on enough people at different average levels of blood sugar to determine the optimal intake at each level of glucose control. Therefore the existing research supports that people with diabetes may have an increased requirement for the nutrient and the data used to develop the AI are very limited - sounds like a case for trial supplementation to me!
Can I Get Enough Chromium from Food Sources?
As stated above, “enough” may depend on whether or not you have diabetes, and if you have diabetes, it may depend on exactly how high your blood sugar is running! However, the following table provides a reasonable summary of food sources of chromium and their chromium content:
11.0 mcg per ? cup
1.1 mcg per ? cup
2.7 mcg per 1 cup
7.5 mcg per 8 fl. ounces
2.2 mcg per 8 fl. ounces
2.0 mcg per 3 oz.
1.7 mcg per 3 oz.
Apple w/ peel
1.4 mcg per 1 medium-sized
1.0 mcg per 1 medium-sized
(Source: Anderson et al. 1992 referenced by: http://lpi.oregonstate.edu/infocenter/minerals/chromium/ accessed 9-25-06).
What’s with all the Long Names and Different Forms?
If you have walked through a nutritional supplement store or looked for supplements online you will have found that chromium sold in all sorts of strengths and forms including Chromium GTF, chromium picolinate, chromium polynicotinate, chromium chloride, chromium-enriched brewer’s yeast, and many more. Unfortunately, the form of chromium supplemented has not been held constant in all of the clinical research, and therefore we do not have a lot of information on any one type of chromium.
Unfortunately, the form of chromium supplemented has not been held constant in all of the clinical research, and therefore we do not have a lot of information on any one type of chromium.
However we do have a little bit of research on many of the types! When looking specifically at chromium absorption, a study published in 2004 showed that the following forms were the best absorbed (commonly available forms in decreasing order): picolinate>pidolate>nicotinate>chloride (Anderson et al. 2004).
Additional forms of chromium were tested, including forms containing the amino acid histidine and showed greater absorption than those listed above, however to my knowledge these forms are not readily available as supplements.
So does this mean that other forms are not useful? Not necessarily, but it may mean that a larger dose would be required to achieve the same result. Also, less is known about the safety of other forms and therefore it means that the long names and fancy claims may not translate into added benefit for your health!
Chromium Supplementation in Diabetes: What the Research Shows
Chromium supplementation began getting a lot of press following a landmark study published in 1997 by Dr. Richard Anderson et al. from the US Dept. of Agriculture (USDA). The study was performed in China and demonstrated in one of the first well-designed studies that people with diabetes who took between 600-1000 mcg per day demonstrated a striking reduction in their blood glucose (measured by hemoglobin A1c) and a reduction in cholesterol - within six months. You may find this study cited by many, many supplement companies trying to sell their products.
Chromium supplementation began getting a lot of press following a landmark study published in 1997 by Dr. Richard Anderson et al. from the US Dept. of Agriculture (USDA).
While this study is monumental because it demonstrated chromium supplementation may be beneficial in a very well-controlled study, the study has also been criticized because it was performed in China, a country in which chromium intake from the diet is poor, rather than in the United States. Despite the controversy, the number of people in the United Stated estimated to supplement chromium is 10 million! Obviously more research needed to be performed…
And more research has been done...in fact three excellent studies have been published in the last two years that have added to the controversy. First in 2005, Gunton et al. published a study in people with one type of pre-diabetes, or impaired glucose tolerance (IGT) (Gunton et al. 2005). The study supplemented 800mcg of chromium as chromium picolinate for three months and found no benefit, suggesting for the first time that chromium supplementation does not appear to prevent diabetes in this population. Criticism of this article included that the researchers used too low of a dose (Komorowski et al. 2005).
With two well-controlled studies of chromium showing no benefit, times looked bleak for the once promising nutrient for diabetes.
Just this year another chromium study was published which investigated chromium supplementation in people who were using insulin to treat their diabetes. The researchers, Kleefstra et al., were monitoring average blood glucose (measured by hemoglobin A1c) as well as insulin use over six months in research subjects taking either 500mcg chromium, 1000mcg chromium or placebo. Although not in the United States, their research was performed in the Netherlands, and therefore the study was in a Westernized culture similar to that of the United States. The researchers found no benefit from supplemental chromium; average blood sugar did not improve nor did insulin dose need to be lowered during the study. Critics of this study suggested the study participants were too advanced in their diabetes, too insulin resistant to benefit and therefore perhaps the dose of chromium was not high enough. Regardless, the results should not be used to make general statements about chromium, simply that chromium may not be beneficial in this population at the dose used in the study.
With two well-controlled studies of chromium showing no benefit, times looked bleak for the once promising nutrient for diabetes. This year, just when all hope for chromium was near lost, Martin et al. published what I think was a brilliantly designed study investigating chromium in people with diabetes who take the medication glipizide (Martin et al. 2006). The study by Martin et al. studied 1000 mcg of chromium as chromium picolinate in 39 people, for 24 weeks. At the end of the study, those who took chromium had an average hemoglobin A1c reduction of 1.13%, improved insulin sensitivity and had an improvement in their percent body fat! Since, Glipizide is a “first-line” oral medications for the treatment of diabetes, studying chromium with this medication has significant clinical value!No prior study had ever before studied chromium in people taking a single type of medication. This type of study has value because each medication has a known mechanism of action and therefore combining chromium with some medications may have benefit while combining it with others may have no benefit at all; simply combining chromium with all medication types may reduce a researcher’s ability to demonstrate significant changes- and limits clinical utility of the research for those of us in practice!
...we are still waiting for a dose-finding study to be performed that identifies the most effective - and safest - dose for a range of blood sugar values.
These studies help physicians better inform their patients about using chromium in diabetes, yet the information is extremely limited. For example, we now know about one form of chromium in combination with one prescription medication, yet we know little about how it combines with other medications. Similarly, although chromium appears to be very safe as a nutritional supplement we do not know if it safe in people with diabetes who have complications such as kidney disease, heart disease, or impaired vision. Also, we are still waiting for a dose-finding study to be performed that identifies the most effective - and safest - dose for a range of blood sugar values.
What is the Bottom Line?
Some of the initial chromium research performed by Dr. Anderson was funded by the Diabetes Action Research and Education Foundation.
The American Diabetes Association (ADA) finally incorporated a discussion of chromium into their 2006 Standards of Medical Care in Diabetes guidelines (ADA. 2006). The ADA discourages chromium supplementation stating, “Benefit from chromium supplementation in people with diabetes or obesity has not been conclusively demonstrated and, therefore, cannot be recommended” (ADA, 2006).
Did you know? Some of the initial chromium research performed by Dr. Anderson was funded by the Diabetes Action Research and Education Foundation (Anderson et al. J. Dia Med. 1998). Your support of Diabetes Action helps research get performed that improves the health of millions of people with diabetes. Obviously more research is needed to help confirm or refute the value of chromium in the treatment of diabetes. Both Diabetes Action Research and Education Foundation and the National Center for Complementary and Alternative Medicine (NCCAM) are helping to address this need through their funding of innovative research!
In the meantime however, my opinion is that for most people with diabetes, chromium is a safe supplement to try and is even recommended if you take Glipizide or a similar medication. As always, I recommend this be done in discussion with your health care team, including your complementary medicine provider. I also recommend you try a dose and form of chromium that has been well-studied for safety, like chromium picolinate, and that you use a brand that was used in the clinical research (although I am not going to endorse a specific brand in this article, with a little sleuthing you can find out which brand has been used in most of the positive chromium research).
Finally, in order to fully evaluate whether chromium supplementation is right for you, I recommend you not make changes to your medications while you are trying it; ask your doctor if it safe for you to perform this therapeutic trial and ask them to measure your hemoglobin A1c before and after a three-six month trial. Being disciplined in your home glucose monitoring will also help this trial be safe and you will allow you to notice changes earlier than waiting to have your hemoglobin A1c rechecked! As always, any improvements you notice from chromium supplementation should add to the benefits experienced from a healthy, vegetable-dense diet and a daily exercise regime; improvements from chromium do not give you clearance for dietary indiscretion - nor should dietary indiscretion lead you to take more chromium!
For Extra Reading…
I recommend the Linus Pauling Institute (LPI) at Oregon State University for extra reading on chromium or other nutrients. The LPI website is: http://lpi.oregonstate.edu/infocenter/minerals/chromium/
The research scientists at LPI have devoted their lives in pursuit of new insights into the role of nutrients and nutrition in health and disease!
A recent study has challenged the American Diabetes Association (ADA) dietary guidelines!
A clinical trial just published compared the ADA recommended diet to a vegan diet (no animal products) and found the vegan diet improved blood sugar, improved cholesterol, improved markers of kidney function, and allowed more medication reductions compared to the ADA diet (Barnard, et al. Diabetes Care. 2006).
As vegan diets can be hard to follow, I recommend talking to a nutritionist or naturopathic physician about planning a vegan diet that is nutritionally complete!
Ryan Bradley, ND, MPH is a naturopathic doctor, clinical researcher and epidemiologist in San Diego, CA. He is an Associate Professor and Assistant Director of Research at the National University of Natural Medicine in Portland, OR and an Assistant Professor in the Department of Family Medicine and Public Health at the University of California, San Diego.
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