The Dangers of Energy Drinks

Energy drinks have become increasingly popular in recent years. There are many brands on the market. Each contain caffeine and some have added stimulants such as guarana, an herbal form of more caffeine, as well as ginseng. Most of these drinks, in moderation, are probably relatively harmless for healthy people. However, when consumed to excess or by those with certain medical conditions, they may have harmful effects. 



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Sugar: The Bitter Truth (Lecture)

Robert H. Lustig, MD is Professor of Clinical Pediatrics, at the University of California, San Francisco (UCSF). He is nationally recognized in the field of neuroendocrinology, with an emphasis on the regulation of energy balance by the central nervous system. Dr. Lustig has a special interest in childhood obesity. He has become publicly notable through his efforts to draw attention to the effects that the natural sugar fructose can have on human and especially children’s health if consumed in large amounts. On May 26, 2009, Robert Lustig gave this lecture called “Sugar: The Bitter Truth” which was posted on YouTube the following July and has become a viral success with over a million viewings. In this lecture, Lustig notably calls fructose a “poison” and compares its metabolic effects with those of ethanol. He is particularly critical of the widespread use of High Fructose Corn Syrup in the United States.

Sugar: The Bitter Truth. Series: UCSF Mini Medical School for the Public [7/2009] [Health and Medicine] [Show ID: 16717].


Fructose Consumption Increases Risk Factors for Heart Disease

Study suggests U.S. Dietary Guideline for Upper Limit of Sugar Consumption is too High:

A recent study accepted for publication in The Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM) found that adults who consumed high fructose corn syrup for two weeks as 25 percent of their daily calorie requirement had increased blood levels of cholesterol and triglycerides, which have been shown to be indicators of increased risk for heart disease.

The American Heart Association recommends that people consume only five percent of calories as added sugar. The Dietary Guidelines for Americans 2010 suggest an upper limit of 25 percent or less of daily calories consumed as added sugar. To address this discrepancy in recommended consumption levels, researchers examined what happened when young overweight and normal weight adults consumed fructose, high fructose corn syrup or glucose at the 25 percent upper limit.

“While there is evidence that people who consume sugar are more likely to have heart disease or diabetes, it is controversial as to whether high sugar diets may actually promote these diseases, and dietary guidelines are conflicting,” said the study’s senior author, Kimber Stanhope, PhD, of the University of California, Davis. “Our findings demonstrate that several factors associated with an elevated risk for cardiovascular disease were increased in individuals consuming 25 percent of their calories as fructose or high fructose corn syrup, but consumption of glucose did not have this effect.”

In this study, researchers examined 48 adults between the ages of 18 and 40 years and compared the effects of consuming 25 percent of one’s daily calorie requirement as glucose, fructose or high fructose corn syrup on risk factors for cardiovascular disease. They found that within two weeks, study participants consuming fructose or high fructose corn syrup, but not glucose, exhibited increased concentrations of LDL cholesterol, triglycerides and apolipoprotein-B (a protein which can lead to plaques that cause vascular disease).

“These results suggest that consumption of sugar may promote heart disease,” said Stanhope. “Additionally our findings provide evidence that the upper limit of 25 percent of daily calories consumed as added sugar as suggested by The Dietary Guidelines for American 2010 may need to be re-evaluated.”

Also working on the study were: Andrew Bremer, Guoxia Chen, Tak Hou Fong, Vivien Lee, Roseanne Menorca, Valentia Medici, Peter Havel and Nancy Keim of the University of California, Davis; Katsuyuki Nakajima and Takamitsu Nakano of Otsuka Pharmaceutical Co. in Tokyo, Japan; and Yasuki Ito of Denka Seiken Co. in Tokyo, Japan.

The article, “Consumption of fructose and high fructose corn syrup increase postprandial triglycerides, LDL-cholesterol, and apolipoprotein-B in young men and women,” appears in the October 2011 issue of JCEM.


Treating Obesity Via Brain Glucose Sensing


The past two decades have witnessed an epidemic spread of obesity-related diseases in Western countries. Elucidating the biological mechanism that links overnutrition to obesity could prove crucial in reducing obesity levels. In the July 26 issue of PLoS Biology, Dr. Dongsheng Cai and his research team at Albert Einstein College of Medicine describe a pathway that directs the brain to sense the body’s glucose dynamics, and they find that a defect of this glucose sensing process contributes to the development of obesity and related disease. Importantly, the team also found that correction of this defect can normalize the whole-body energy balance and treat obesity.

The hypothalamus in the brain plays a key role in controlling energy and body weight balance. To maintain balance between energy intake and energy expenditure, the hypothalamus constantly gauges the whole-body’s energy levels by sampling circulating hormones (e.g. insulin and leptin) as well as nutrients (e.g., glucose). Although we know quite a bit about the hormonal pathways in the hypothalamic regulation of feeding, the mechanisms for hypothalamic nutrient sensing are much less clear. Moreover, a causal link between a nutrient sensing defect and obesity remains to be established. The team led by Dr. Cai discovered a novel role of a protein complex, hypoxia-inducible factor (HIF), in hypothalamic glucose sensing and whole-body energy balance in mice.

HIF is a nuclear transcription factor which induces hypoxia response. When tissue oxygen level is low, HIF is activated to promote cellular metabolic adaption and survival. Recent research has appreciated the involvement of HIF in the metabolism of tumor cells. “However, an intriguing but unexplored question is whether HIF can be important for the regulation of whole-organism metabolism, and if so, which tissue and cells are responsible.” says Cai, who is an expert in neuroendocrinology and metabolism.

Cai and his group examined HIF in the hypothalamus and, surprisingly, found that it can be activated by glucose and that this regulation was associated with appetite control in mice. In identifying the cellular and molecular basis, the team found that in response to glucose, HIF acts in a unique group of hypothalamic nutrient-sensing neurons to induce expression of POMC gene – a gene which has been known to play a key part in hypothalamic control of feeding and body weight. Most excitingly, the team demonstrated the therapeutic potential of targeting hypothalamic HIF to control obesity. By enhancing the hypothalamic HIF activity via gene delivery, mice become resistant to obesity despite the condition of nutritional excess.

“It was an exciting discovery,” explains Cai, “Our study is the first to show that beyond its classical oxygen-sensing function in many cells, HIF in the hypothalamic neurons can sense glucose to control the whole-body balance of energy intake and expenditure which is critical for body weight homeostasis.” Overall, this study reveals a crucial role for neuronal HIF in bridging the brain’s glucose sensing with the brain’s regulation of body weight and metabolic physiology. These findings also highlight a potential implication for developing neuronal HIF activators in treating and preventing obesity and related diseases.



Zhang H, Zhang G, Gonzalez FJ, Park S-m, Cai D.  Hypoxia-Inducible Factor Directs POMC Gene to Mediate Hypothalamic Glucose Sensing and Energy Balance Regulation. PLoS Biol 2011; 9 (7):  e1001112. doi:10.1371/journal.pbio.1001112



Too Much Sugar Is Bad, But Which Sugar Is Worse: Fructose Or Glucose?

In 2005, the average American consumed 64 kg of added sugar, a sizeable proportion of which came through drinking soft drinks. Now, in a 10-week study, Peter Havel and colleagues, at the University of California at Davis, Davis, have provided evidence that human consumption of fructose-sweetened but not glucose-sweetened beverages can adversely affect both sensitivity to the hormone insulin and how the body handles fats, creating medical conditions that increase susceptibility to heart attack and stroke.

In the study, overweight and obese individuals consumed glucose- or fructose-sweetened beverages that provided 25% of their energy requirements for 10 weeks. During this period, individuals in both groups put on about the same amount of weight, but only those consuming fructose-sweetened beverages exhibited an increase in intraabdominal fat. Further, only these individuals became less sensitive to the hormone insulin (which controls glucose levels in the blood) and showed signs of dyslipidemia (increased levels of fat-soluble molecules known as lipids in the blood). As discussed in an accompanying commentary by Susanna Hofmann and Matthias Tschöp, although these are signs of the metabolic syndrome, which increases an individual’s risk of heart attack, the long-term affects of fructose over-consumption on susceptibility to heart attack remain unknown.


Stanhope KL, Schwarz JM, Keim NL, Griffen SC, Bremer AA, Graham JL, et al. Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans. J Clin Invest. 2009;119 (5): 1322-34.

Hofmann SM, Tschöp MH. Dietary sugars: a fat difference. J Clin Invest. 2009;119 (5): 1089-92.