Chromium deficiency is described as the consequence of an insufficient dietary intake of the mineral chromium. Chromium was first proposed as an essential element for normal glucose metabolism in 1959, and was widely accepted as being such by the 1990s. Cases of deficiency were described in people who received all of their nutrition intravenously for long periods of time.
The essentiality of chromium has been challenged. The authorities for the European Union do not recognize chromium as an essential nutrient. The United States does, and identifies as Adequate Intake for adults as between 25 and 45 μg/day, depending on age and sex. Dietary supplements containing chromium are widely available in the United States, with claims for benefits for fasting plasma glucose, hemoglobin A1C and weight loss. Reviews report the changes as modest, and without scientific consensus that the changes have a clinically relevant impact.
Signs and symptoms
According to the Dietary Reference Intake review, neither plasma nor urine concentrations can serve as useful clinical indicators of chromium status. Before chromium became a standard ingredient in total parenteral nutrition (TPN), people getting TPN as their sole source of nutrition developed symptoms that were reversed within two week after chromium was added.
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for chromium in 2001. For chromium there was not sufficient information to set EARs and RDAs, so needs are described as estimates for Adequate Intakes (AIs). The current AIs for chromium for women ages 14 and up is 25 μg/day up to age 50 and 20 μg/day for older. AI for pregnancy is 30 μg/day. AI for lactation is 45 μg/day. For men ages 14 and up 35 μg/day up to age 50 and 30 μg/day for older. For infants to children ages 1–13 years the AI increases with age from 0.2 to 25 μg/day. As for safety, the IOM sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of chromium there is not yet enough information and hence no UL. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).
Japan designate chromium as an essential nutrient, identifying 10 μg/day as an Adequate Intake for adults.
The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. The EFSA does not consider chromium to be an essential nutrient, and so has not set PRIs, AIs or ULs. Chromium is the only mineral for which the United States and the European Union disagree on essentiality.
For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV). For chromium labeling purposes 100% of the Daily Value was 120 μg, but as of May 27, 2016 it was revised to 35 μg to bring it into agreement with the RDA. A table of the old and new adult Daily Values is provided at Reference Daily Intake. The original deadline to be in compliance was July 28, 2018, but on September 29, 2017 the FDA released a proposed rule that extended the deadline to January 1, 2020 for large companies and January 1, 2021 for small companies.
Approximately 2% of ingested chromium(III) is absorbed, with the remainder being excreted in the feces. Amino acids, vitamin C and niacin may enhance the uptake of chromium from the intestinal tract. After absorption, this metal accumulates in the liver, bone, and spleen. Trivalent chromium is found in a wide range of foods, including whole-grain products, processed meats, high-bran breakfast cereals, coffee, nuts, green beans, broccoli, spices, and some brands of wine and beer. Most fruits and vegetables and dairy products contain only low amounts.
Chromium is an ingredient in total parenteral nutrition (TPN) because deficiency can occur after months of intravenous feeding with chromium-free TPN. For this reason, chromium is added to TPN solutions, along with other trace minerals. It is also in nutritional products for preterm infants. In the United States, chromium-containing products are sold as non-prescription dietary supplements. Chemical compounds include chromium chloride, chromium citrate, chromium(III) picolinate, chromium(III) polynicotinate, and other chemical compositions.
Given the evidence for chromium deficiency causing problems with glucose management in the context of intravenous nutrition products formulated without chromium, research interest turned to whether chromium supplementation for people who have type 2 diabetes but are not chromium deficient could benefit. Looking at the results from four meta-analyses, one reported a statistically significant decrease in fasting plasma glucose levels (FPG) and a non-significant trend in lower hemoglobin A1C (HbA1C). A second reported the same,, a third reported significant decreases for both measures, while a fourth reported no benefit for either. A review published in 2016 listed 53 randomized clinical trials that were included in one or more of six meta-analyses. It concluded that whereas there may be modest decreases in FPG and/or HbA1C that achieve statistical significance in some of these meta-analyses, few of the trials achieved decreases large enough to be expected to be relevant to clinical outcome. The authors also mentioned that trial design was for chromium as an addition to standard glycemic control medications, and so did not evaluate chromium as a first treatment for type 2 diabetes, or for prevention of progression from pre-diabetes to diabetes. The conclusion was that "...there is still little reason to recommend chromium dietary supplements to achieve clinically meaningful improvements in glycemic control." The American Diabetes Association publishes a standards of care review every year. The 2018 review makes no mention of chromium supplementation as a possible treatment.
Government-approved health claims
In 2005, the U.S. Food and Drug Administration approved a Qualified Health Claim for chromium picolinate with a requirement for very specific label wording: "One small study suggests that chromium picolinate may reduce the risk of insulin resistance, and therefore possibly may reduce the risk of type 2 diabetes. FDA concludes, however, that the existence of such a relationship between chromium picolinate and either insulin resistance or type 2 diabetes is highly uncertain." In 2010, chromium(III) picolinate was approved by Health Canada to be used in dietary supplements. Approved labeling statements included: "...provides support for healthy glucose metabolism." The European Food Safety Authority (EFSA) approved claims in 2010 that chromium contributed to normal macronutrient metabolism and maintenance of normal blood glucose concentration.
Two systematic reviews looked at chromium supplements as a mean of managing body weight in overweight and obese people. One, limited to chromium picolinate, a popular supplement ingredient, reported a statistically significant -1.1 kg (2.4 lb) weight loss in trials longer than 12 weeks. The other included all chromium compounds and reported a statistically significant -0.50 kg (1.1 lb) weight change. Change in percent body fat did not reach statistical significance. Authors of both reviews considered the clinical relevance of this modest weight loss as uncertain/unreliable. The EFSA reviewed the literature and concluded that there was insufficient evidence to support a claim.
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