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 The leading web portal for pharmacy resources, news, education and careers February 25, 2017
Pharmacy Choice - Dietary Supplements Disease State Management - February 25, 2017

Dietary Supplements Disease State Management

Dietary Supplements: Do They Play a Role in Obesity
by Joanne Conrad, MS, RD

The most recent data (2011-2014) show that more than one-third of adults and 17% of youth in the United States are obese. Another third of the population is overweight. More than two billion people around the world are estimated to be obese or overweight.

Overweight is defined as extra body weight from muscle, bone, fat and/or water. The term obesity refers to an excess amount of fat, and is generally associated with a BMI over 30 kg/m2.

Overweight and obesity lead to adverse metabolic effects on blood pressure, cholesterol, triglycerides and insulin resistance. Risks of coronary heart disease, ischemic stroke and type 2 diabetes increase steadily with increasing body mass index (BMI), a measure of weight relative to height. Raised body mass index also increases the risk of many cancers and overall mortality.

Individuals seeking to reduce weight may turn to the use of dietary supplements. It is often difficult to determine whether a supplement is beneficial since dietary supplements do not require FDA approval for efficacy and safety before being marketed to the public. Many supplements lack peer-reviewed scientific data.

A review of popular weight loss supplements is provided below.

Chromium
Chromium research is focused on its use in supplement form to promote weight loss, to increase energy, and to improve body composition. Chromium picolinate is the most stable and bioavailable form of chromium.

There is conflicting evidence for the benefit of chromium and weight loss. Few serious adverse effects have been linked to chromium. Chromium may lower blood glucose levels if it is taken with anti-diabetic drugs. The absorption of beta blockers, insulin, nicotinic acid and NSAIDS may be enhanced if they are taken together with chromium.

Caffeine
Caffeine is a methylxanthine compound that is structurally related to theophylline and theobromine. It is 100% bioavailable after oral administration and is metabolized principally in the liver. Many of caffeine's effects are believed to occur by means of competitive antagonism at adenosine receptors. Caffeine's role in weight loss is based on its ability to increase resting energy expenditure, cellular thermogenesis, non-oxidative fatty acid turnover and lipid oxidation. It is rated as possibly effective for weight loss.

Caffeine has "Generally Recognized as Safe" status in the United States. Doses greater than 250-300 mg per day have been associated with adverse effects, such as sleep disturbance and psychological dependence. Caffeine is metabolized by CPY 1A2 and could theoretically interfere with drugs metabolized by CPY 1A2.

Green Tea
Green tea is rich in catechins, particularly epigallocatechin-3-gallate (EGCG). Catechins are a category of polyphenols, which are potent antioxidants. There are three ingredients in green tea that have been studied: catechins, theanine, and caffeine. It is thought that the catechins and theanine have anti-obesity effects on fat homeostasis, by increasing thermogenesis and reducing fat absorption. There is also some evidence that EGCG specifically might suppress appetite. The caffeine content is also believed to help influence weight loss via these same mechanisms and its ability to increase resting energy expenditure.

The available evidence supports a role of green tea in weight loss; however, the extent of the effects obtained is still subject to debate. Green tea appears to be safe for most adults when used in moderate amounts. The safety issues and drug interactions for caffeine discussed previously apply to green tea. Hepatotoxicity has been reported with green tea extracts but not with green tea itself. Studies of the interactions of green tea with drugs are limited.

Green Coffee
Green coffee beans are coffee beans that have not yet been roasted resulting in a higher level of chlorogenic acid compared to roasted coffee beans. The chlorogenic acid constituent in green coffee is thought to be responsible for several of its pharmacological effects, such as modulating glucose metabolism, inhibiting fat accumulation and altering body fat distribution. Green coffee also contains caffeine (see above). Several clinical trials show that green coffee extract might modestly reduce weight.

The following supplements are advertised for weight loss and are often found in combination with other ingredients. There is limited evidence of effectiveness for these supplements.

Raspberry ketone might alter lipid metabolism by increasing norepinephrine-induced lipolysis and thermogenesis.

Ma Huang, a traditional Chinese herbal product, is a source of ephedra. Although the FDA has banned the sale of other products containing ephedra, Ma Huang is still available.

Bitter Orange Extract contains synephrine, which is similar to ephedra.

Guarana is rich in caffeine, which is responsible for most of its effects.

Garcinia cambogia contains the active ingredient hydroxycitric acid which is thought to inhibit the body's production of lipids via an enzyme called citrate lyase.

The bottom line: more clinical research must be conducted before most dietary supplements can be recommended to the public to manage obesity.
References
  1. www.naturaldatabase.com Natural Medicines Comprehensive Database Monographs.
  2. Natural Medicines in the Clinical Management of Obesity. www.nautraldatabase.com
  3. www.nccih.nih.gov
  4. www.ods.nih.gov
  5. www.ncbi.nim.nih.gov/pubmed
  6. Ogden, Cynthia L PhD; Margaret D Carroll, MS PH; Cheryl D Frayar, MSPH; Katherine M Flegal PhD. Prevalence of Obesity Among Adults and Youth: United States, 2011-2014. US Department of Health and Human Services, Center for Disease Control and Prevention, November 2015.
  7. World Health Organization; Global Health Observation Data, Obesity.


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