Caffeine as a flavor additive in soft-drinks

Over 60% of soft-drinks sold in the United States contain caffeine, a mildly addictive psycho-active chemical, as a flavor additive. Using sweeteners as controls, we assessed whether caffeine has flavor activity in a cola soft-drink. A forced-choice triangle discrimination methodology was used to determine detection thresholds of caffeine in sweeteners and a cola beverage. The subjects (n=30, 28 female, 23±4 years old) were trained tasters and completed over 1600 discrimination tests during the study. The mean detection thresholds for caffeine in the sweet solutions were: 0.333±0.1 mM sucrose; 0.467±0.29 mM aspartame; 0.462±0.3 mM sucralose, well below the concentration in common cola beverages (0.55–0.67 mM). A fixed concentration of caffeine, corresponding to the concentration of caffeine in a common cola beverage (0.67 mM) was added to the sweeteners and a non-caffeinated cola beverage. Subjects could distinguish between caffeinated and non-caffeinated sweeteners (p<0.001), but all subjects failed to distinguish between caffeinated and non-caffeinated cola beverage (p=1.0). Caffeine has no flavor activity in soft-drinks yet will induce a physiologic and psychologic desire to consume the drink.

Modification of the bitterness of caffeine

Caffeine is the worlds most consumed psychoactive chemical and as such is a valuable commodity to the food and beverage industry. Caffeine also activates the bitter taste system causing a potential problem for manufacturers wanting to develop products containing caffeine. In the present study both oral peripheral and central cognitive strategies were used in an attempt to suppress the bitterness of caffeine. Subjects (n = 33) assessed the influence of sodium gluconate (100 mM), zinc lactate (5 mM), sucrose (125 mM and 250 mM), milk (0%, 2% and 4% milk fat), and aromas (coffee, chocolate, mocha) on the bitterness of caffeine (1.5, 3 and 4.5 mM). The oral peripheral strategies proved most effective at suppressing the bitterness of caffeine: zinc lactate (−71%, p < 0.05), non-fat milk (−49%, p < 0.05), and sodium gluconate (−31%). Central cognitive strategies were partially effective: 250 mM sucrose (−47%, p < 0.05) and mocha aroma (−10%) decreased bitterness, while chocolate (+32%) and coffee (+17%) aromas increased perceived bitterness. Overall, zinc lactate was the most effective bitterness inhibitor, however the utility of zinc in foods is negated by its ability to inhibit sweetness.

The 'caffeine-sweetness' effect; potential reduction of energy in caffeinated sugar-sweetened soft drinks

Background – Excessive consumption of sugar sweetened beverages (SSB) is a contributing factor in the occurrence of overweight and obesity. The high energy intake, low satiation, high glycemic index, and intense marketing are all thought to contribute to their over consumption. In addition, the role of the mildly-addictive chemical caffeine in SSB has been questioned (Griffiths and Vernotica, 2000, Keast and Riddell, 2007). We have previously shown that low concentrations of caffeine may decrease sweetness of sugars and thereby result in excess energy in SSB formulations (Ebbeling et al., 2006).
Objective – Without noticeably affecting flavour, to determine potential energy reduction when decreasing sucrose concentration from caffeinated and de-caffeinated SSB.
Design – Human psychophysical taste evaluations in water, sucrose and model SSB. Triangle forced-choice ascending method of limits was used to determine caffeine taste threshold in water and sucrose (n= 62). Directional paired comparison tests to determine 1/ the influence of caffeine on sweetness of sucrose (n= 23), and 2/ the nonperceivable difference when decreasing the sucrose and caffeine concentrations in a model SSB (n= 30).
Outcomes – Caffeine, at sub-threshold concentrations in common SSB (0.67mM) can be perceived in sucrose solutions because it significantly inhibits sweetness (p<0.001), the ‘caffeine sweetness effect’. Presumably coremoval of caffeine and sucrose could be achieved without affecting the sweetness of the SSB. Removing caffeine from the model SSB allowed an energy reduction of 137.4 KJ per 500 ml serving (12.6% sucrose reduction) without noticeably affecting flavour for 80% of the population. The energy reduction possible without co-removal of caffeine was a more modest 32 KJ per 500 ml serving (3.5% sucrose reduction).
Conclusion – Sub-threshold concentrations of caffeine suppress sweetness resulting in higher concentrations of sugars in SSB. Excessive consumption of SSB is linked to the obesity epidemic, and we suggest the removal of caffeine and subsequent removal of 137.4 KJ energy will have long term public health benefits.

The caffeine-calorie effect in sugar-sweetened beverages

The presence of caffeine in sugar-sweetened beverages (SSB) may be an important contributor to the growing obesity epidemic. The removal of caffeine, along with co-removal of a proportion of sugars from the beverage will result in regular SSB consumers reducing their energy intake without the need for other dietary or lifestyle changes.

Caffeine as an ingredient in sugar sweetened beverages

Caffeine is the most widely used psychoactive drug in the world, with more than 80% of the US population classed as regular consumers (Garrett and Griffiths 1998). An analysis of the Continuing Survey of Food Intakes by Individuals (CSFII) in the US indicates that 870/o of US population over 2 years of age consumed caffeine daily and the average intake in caffeine consumers was 193 mg per day or 1.2 mgkg-l per day (Frary er a/ 2005). SSB were the primary source of caffeine in children and adolescents under 18 years of age and provided between 50-64% of the daily caffeine intake. For adults 18-34 years, SSB provided 30% of total daily caffeine, dropping fo llo/o for adults 34 years and older (Frary et a|2005). The total daily intake of caffeine observed in the CSFII is slightly lower that than observed in the 1995 National Nutrition Survey of Australian adults who reported consuming on average 270 mg of caffeine per day. Caffeine intakes amongst children, aged2 to 14 years, were reported as 17 mg per day. It is suggested that cola flavored SSB provide around 62o/, of this intake (Desbrow et al 2004).

Is the popularity of caffeinated foods mere coincidence? Is the flavor coffee, chocolate, tea and cola soft drinks such that without caffeine they would still be widely consumed? Or is the popularity of caffeine containing foods due to the influence of caffeine in the body?

The acute effects of caffeine in a sugar-sweetened beverage on energy consumption

Background: It has been suggested that those who are habitually high caffeine consumers ingest greater quantities of snack foods both in and outside the laboratory. Sugar-sweetened beverages (SSBs) are a major contributor to caffeine consumption and evidence links SSB consumption with poor dietary intake.

Objective: To determine whether varying the concentration of caffeine in SSBs influences snack food consumption and energy intake.

Methods: Caffeine taste thresholds were assessed using the International Standards Organization method for assessing taste sensitivity. In a crossover study design, participants (n=23, 26±5 years old, 58% female) were provided with a standardized meal on 4 days and simultaneously consumed SSBs with varied levels of caffeine (0, 0.67, 1.16, and 1.65 mM). The intake of food and beverage was recorded following each meal session.

Results: A one way between groups analysis of variance revealed no significant main effect of caffeine concentration on consumption of SSBs [F (3, 92)=0.154, p=0.927] or food [F (3, 92)=0.305, p=0.822]. Pearson correlation analysis identified no significant correlations between the amount of food and SSB consumed (R=−0.031–0.415, p=0.062–0.893), or the amount of food and SSB consumed with body mass index and waist circumference (R=0.000 to −0.380, p=0.073–0.999). An individual's oral sensitivity to caffeine was not associated with SSB consumption (R=0.045 to −0.309, p=0.152–0.839) or the consumption of food (R=−0.052 to −0.327, p=0.128–0.812).

Conclusions: The concentration of caffeine in SSBs did not influence the amount of food or SSB consumed.

Induced alkalosis and caffeine supplementation : effects on 2,000-m rowing performance

Introduction: The purpose of this investigation was to determine the effect of ingested caffeine, sodium bicarbonate, and their combination on 2,000-m rowing performance, as well as on induced alkalosis (blood and urine pH and blood bicarbonate concentration [HCO3 -]), blood lactate concentration ([La-]), gastrointestinal symptoms, and rating of perceived exertion (RPE). Methods: In a double-blind, crossover study, 8 well-trained rowers performed 2 baseline tests and 4 × 2,000-m rowing-ergometer tests after ingesting 6 mg/kg caffeine, 0.3 g/kg body mass (BM) sodium bicarbonate, both supplements combined, or a placebo. Capillary blood samples were collected at preingestion, pretest, and posttest time points. Pairwise comparisons were made between protocols, and differences were interpreted in relation to the likelihood of exceeding the smallest-worthwhile- change thresholds for each variable. A likelihood of >75% was considered a substantial change. Results: Caffeine supplementation elicited a substantial improvement in 2,000-m mean power, with mean (± SD) values of 354 ± 67 W vs. placebo with 346 ± 61 W. Pretest [HCO3 -] reached 29.2 ± 2.9 mmol/L with caffeine + bicarbonate and 29.1 ± 1.9 mmol/L with bicarbonate. There were substantial increases in pretest [HCO3 -] and pH and posttest urine pH after bicarbonate and caffeine + bicarbonate supplementation compared with placebo, but unclear performance effects. Conclusions: Rowers' performance in 2,000-m efforts can improve by ~2% with 6 mg/kg BM caffeine supplementation. When caffeine is combined with sodium bicarbonate, gastrointestinal symptoms may prevent performance enhancement, so further investigation of ingestion protocols that minimize side effects is required. ABSTRACT FROM AUTHOR

Effect of caffeine supplementation on repeated sprint running performance

This study examined the effects of 6 mg-kg-1 caffeine ingestion in team-sport players (N.=10) on repeated-sprint running performance (5 sets of 6 x 20 m) and reaction times, 60 min after caffeine or placebo ingestion. Methods. Best single sprint and total set sprint times, blood lactate and simple and choice reaction times (RT) were measured. Total sprint times across sets 1, 3 and 5 (departure every 25 s) were significantly faster after caffeine (85.49±5.55 s) than placebo (86.98±5.78 s) (P<0.05). Similarly, total sprint times across sets 2 and 4 (departure every 60 s), were significantly faster after caffeine (55.99±3.64 s) than placebo (56.77±3.74 s) (P<0.05). Significantly higher blood lactates were recorded in caffeine compared to placebo after set 3 (13.1±1.2 vs 10.3±1.4 mmolL ') (P<0.05) and set 5 (13.1±1.3 vs 103±1.6 mmol-L"1) (P<0.01). There were no significant effects on simple or choice RT, although effect sizes suggested improved post-exercise times after caffeine. Caffeine ingestion 60 min prior to exercise can enhance repeated sprint running performance and is not detrimental to reaction times. [PUBLICATION ABSTRACT]

Effect of different protocols of caffeine intake on metabolism and endurance performance

Competitive athletes completed two studies of 2-h steady-state (SS) cycling at 70% peak O2 uptake followed by 7 kJ/kg time trial (TT) with carbohydrate (CHO) intake before (2 g/kg) and during (6% CHO drink) exercise. In Study A, 12 subjects received either 6 mg/kg caffeine 1 h preexercise (Precaf), 6 × 1 mg/kg caffeine every 20 min throughout SS (Durcaf), 2 × 5 ml/kg Coca-Cola between 100 and 120 min SS and during TT (Coke), or placebo. Improvements in TT were as follows: Precaf, 3.4% (0.2-6.5%, 95% confidence interval); Durcaf, 3.1% (-0.1-6.5%); and Coke, 3.1% (-0.2-6.2%). In Study B, eight subjects received 3 × 5 ml/kg of different cola drinks during the last 40 min of SS and TT: decaffeinated, 6% CHO (control); caffeinated, 6% CHO; decaffeinated, 11% CHO; and caffeinated, 11% CHO (Coke). Coke enhanced TT by 3.3% (0.8-5.9%), with all trials showing 2.2% TT enhancement (0.5-3.8%; P < 0.05) due to caffeine. Overall, 1) 6 mg/kg caffeine enhanced TT performance independent of timing of intake and 2) replacing sports drink with Coca-Cola during the latter stages of exercise was equally effective in enhancing endurance performance, primarily due to low intake of caffeine (∼1.5 mg/kg).

Improved 2000-meter rowing performance in competitive oarswomen after caffeine ingestion

Eight competitive oarswomen (age, 22 ± 3 years; mass, 64.4 ± 3.8 kg) performed three simulated 2,000-m time trials on a rowing ergometer. The trials, which were preceded by a 24-hour dietary and training control and 72 hours of caffeine abstinence, were conducted 1 hour after ingesting caffeine (6 or 9 mg · kg-1 body mass) or placebo. Plasma free fatty acid concentrations before exercise were higher with caffeine than placebo (0.67 ± 0.34 vs. 0.72 ± 0.36 vs. 0.30 ± 0.10 mM for 6 and 9 mg · kg-1caffeine and placebo, respectively; p < .05). Performance time improved 0.7% (95% confidence interval [CI] 0 to 1.5%) with 6 mg · kg-1 caffeine and 1.3% (95% CI 0.5 to 2.0%) with 9 mg · kg-1 caffeine. The first 500 m of the 2,000 m was faster with the higher caffeine dose compared with placebo or the lower dose (1.53 ± 0.52 vs. 1.55 ± 0.62 and 1.56 ± 0.43 min; p = .02). We concluded that caffeine produces a worthwhile enhancement of performance in a controlled laboratory setting, primarily by improving the first 500 m of a 2,000-m row.

Caffeine increases sugar-sweetened beverage consumption in a free-living population: a randomised controlled trial

Excessive sugar-sweetened beverage (SSB) consumption has been associated with overweight and obesity. Caffeine is a common additive to SSB, and through dependence effects, it has the potential to promote the consumption of caffeine-containing foods. The objective of the present study was to assess the influence that caffeine has on the consumption of SSB. Participants (n 99) were blindly assigned to either a caffeinated SSB (C-SSB) or a non-caffeinated SSB (NC-SSB) group. Following randomisation, all participants completed a 9 d flavour-conditioning paradigm. They then completed a 28 d ad libitum intake intervention where they consumed as much or as little of C-SSB or NC-SSB as desired. The amount consumed (ml) was recorded daily, 4 d diet diaries were collected and liking of SSB was assessed at the start and end of the intervention. Participants (n 50) consuming the C-SSB had a daily SSB intake of 419 (sd 298) ml (785 (sd 559) kJ/d) over the 28 d intervention, significantly more than participants (n 49) consuming the NC-SSB (273 (sd 278) ml/d, 512 (sd 521) kJ/d) (P< 0·001). A trained flavour panel (n 30) found no difference in flavour between the C-SSB and NC-SSB (P>0·05). However, participants who consumed the C-SSB liked the SSB more than those who consumed the NC-SSB (6·3 v. 6·0 on a nine-point hedonic scale, P= 0·022). The addition of low concentrations of caffeine to the SSB significantly increases the consumption of the SSB. Regulating caffeine as a food additive may be an effective strategy to decrease the consumption of nutrient-poor high-energy foods and beverages.