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Year : 2019  |  Volume : 10  |  Issue : 1  |  Page : 16-23  

Swallowing thin liquids from the rim of the cup and through the straw in healthy geriatrics

1 Department of Audiology and Speech-Language Pathology, Nitte Institute of Speech and Hearing, Mangalore, Karnataka, India
2 Department of Audiology and Speech-Language Pathology, Bharati Vidyapeeth (Deemed University), Pune, Maharashtra, India
3 Department of Speech-Langauge Pathology, All India Institute of Speech and Hearing, Mysuru, Karnataka, India

Date of Web Publication4-Feb-2019

Correspondence Address:
Thejaswi Dodderi
Nitte Institute of Speech and Hearing, Mangalore, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jnsbm.JNSBM_167_18

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Context: Literature suggests geriatrics with swallowing difficulty to use straw as a compensatory strategy to drink thin liquids. However, in India, drinking through the straw is traditionally not etiquette of dining and in our observation this practice is changing. Aim: This study aimed to measure the swallowing of thin liquids through the straw in healthy elderly adults (HEAs). Settings and Design: A crossover comparative design with nonrandom sampling was adopted. Subjects and Methods: Fifty volunteers (25 healthy young adults [HYAs] and 25 HEAs) consumed 100 ml lukewarm water from two medium: (a) rim of the cup and (b) through the straw, across four different straw capacities. Swallowing performance was measured by volume/swallow, time/swallow, and swallow capacity. Statistical Analysis Used: Descriptive statistics along with repeated measures analysis of variance (ANOVA) and multivariate ANOVA test were administered on the data. Results: Results revealed HYAs swallowing from rim of the cup to be better than elderly participants that yielded increased volume/swallow. Likewise, in through the straw condition, healthy elderly participants had better swallowing performance. The study also highlights an inverse relationship between straw length and volume. Conclusions: The conclusion drawn is using straw results in decreased swallowing performance and this can be an effective strategy to improve thin liquid swallowing in healthy elders.

Keywords: 100 ml, aging, lukewarm water, swallow capacity, utensil

How to cite this article:
Dodderi T, Karkera ND, Sunil N. Swallowing thin liquids from the rim of the cup and through the straw in healthy geriatrics. J Nat Sc Biol Med 2019;10:16-23

How to cite this URL:
Dodderi T, Karkera ND, Sunil N. Swallowing thin liquids from the rim of the cup and through the straw in healthy geriatrics. J Nat Sc Biol Med [serial online] 2019 [cited 2021 Jun 17];10:16-23. Available from:

   Introduction Top

Hydration is an integral aspect of our health. Oral intake of water occurs with the automatic protection of the airway zone.[1],[2] Swallowing is divided into two categories: (a) sequential swallowing that encompasses continuous ingestion of a large bolus quantity and (b) single-sip swallowing, which occurs for a small bolus quantity.[3],[4] Literature reports that healthy elderly experience difficulty in swallowing thin liquids.[5] Studies on sequential swallowing suggest a high risk of penetration (or airway invasion) in elderly adults, and at times elders may also aspirate (food entering to the airway tract).[5],[6] However, in its nonpathological condition, clinical referrals for swallowing evaluation often get missed due to individuals' self-learned strategies to overcome minor swallowing difficulty. Literature suggests using a spoon and/or straw to be one such modification.[7]

When healthy geriatrics swallowed 100-ml dyed liquid using straw, flexible fiber-optic endoscopic evaluation of swallowing revealed decreased oral spillage, longer swallowing time, and reduced swallow capacity.[8] In another straw-cup comparative study, when 100-ml water was swallowed, drinking through the straw exhibited higher volume per swallow compared with that of the rim of the cup.[9] Longer intraoral dwell time and decreased oral spillage are the advantages of drinking by straw.[8] While straw facilitates longer intraoral dwell time, there is no significant relationship between aspiration and pharygo-laryngeal dwell time in bolus pocketing areas – valleculae and pyriform fossa.[10] Elderly adults have also reported drinking with straw to be easier.[11] However, using straw, particularly in individuals above 70 years, is contradicted since ageing is associated with increased risk of airway invasion due to poor respiratory-phonatory co-ordination and can result in an unsafe swallow.[12]

To our knowledge, several works have attempted to understand the sequential swallowing of thin liquids. Yet, there is no experimental work performed in Indian population. Across the diverse Indian community, thin liquids are consumed from the rim of the cup and this etiquette of dining is passed on from one generation to its forthcoming generation as a tradition. In few cultures, like the orthodox Brahmin community, drinking water by the tumbler's rim touching the lips is prohibited. With time, these practices have faded or evolved and in our clinical observation, elderly adults now use a straw to drink tender coconut and fresh juices among other commercially available refreshments of thin liquids consistency. Hence, the present study aims to: (a) establish a baseline and/or normative data for sequential swallowing through a straw for healthy young adults (HYAs) and healthy elderly adults (HEAs), (b) to report changes in performance between sequential swallowing of 100-ml thin liquids from the rim of the cup and through the straw, and (c) to test if varying straw length and width enhances or diminishes swallowing indices.

   Subjects and Methods Top


This is a crossover comparative study. By nonrandom sampling, fifty volunteers consisting of 25 HYAs aged 18–24 (mean = 20.24; standard deviation [SD] =1.78) years and 25 HEAs aged 61–70 (mean = 68.08; SD = 5.9) years participated in the study. Participants were recruited through an open invitation displayed at a residential colony and a health science campus. An oral interview was performed by a licensed Speech-Language Pathologist to rule out systemic disease, sensory motor issues, neurological deficits, and/or head-and-neck surgery. Four-finger test and trial feed investigation were done to rule out the risk of swallowing impairment.[13] Participants cleared the four-finger test if a strong timely hyo-laryngeal elevation was elicited during dry/saliva swallow which was monitored by the method of palpation. In the trial feeds, 5-ml thin liquid was measured using a standard measuring cup and presented to the participants in a disposable spoon. At their readiness, participants swallowed the 5-ml thin liquids in their natural swallowing style which was deemed as normal/safe swallow on the absence of cough reflex and/or audible aspiration. The risk for dementia was ruled out by Mini-Mental Status Examination with cutoff score >24.[14] Informed consent was taken from each participant prior to data collection. The Institute's Ethics Committee approval was obtained for the study.


The present study used lukewarm water and/or water at room temperature to represent the thin liquid consistency. Previous experimental literature is supportive of using thin liquids as the stimuli to assess sequential swallowing.[8],[10],[11],[15] In the study, the cup used was a semi-transparent disposable cup with a diameter of 7 cm and 6 cm cup length. Likewise, we used straw of two different lengths and widths. Commercially available 15 cm × 0.5 cm straw was used for assessing through the straw condition. This dimension was manually modified into 15 cm × 0.25 cm (maintaining the straw length and decreasing the straw width by half); 7 cm × 0.5 cm (maintaining the straw width and decreasing the straw length by half); and 7 cm × 0.25 cm (decreasing both the straw length and width by half).


Swallowing examination was performed by a licensed Speech-Language Pathologist skilled in performing the timed test of swallowing at the Department of Audiology and Speech-Language Pathology of a multidisciplinary tertiary care hospital. Timed test of swallowing was performed being seated upright on a chair with back rest and the foot placed firm on the ground.[16] 100-ml lukewarm water was gauzed by a standard measuring beaker and later transferred into a 120-ml capacity disposable cup. The participants held the right to choose the preferred hand. This protocol was followed to maintain uniformity across all test conditions.

The standard instructions for simulating the participant's natural style of swallowing was “Continuously swallow the water in a single attempt without spillage.” These instructions are in consonance with earlier sequential swallowing experiments.[4],[8],[17] Each participant swallowed 100-ml lukewarm water in two conditions: (a) baseline swallowing assessment or drinking from the rim of the cup and (b) through the straw across four different permutations.

When the participant was performing the timed test of swallowing, the Speech-Language Pathologist with normal visual acuity observed two online parameters. First, a temporal swallowing index called “total swallowing time” was calculated as the time difference from the rim of the cup/straw touching the lower lip to its subsequent withdrawal. Total swallowing time was monitored using a handheld digital stopwatch and measured in milliseconds. Second, the total number of swallow was calculated by visual observation of the hyolaryngeal movements. One hyolaryngeal elevation and subsequent hyolaryngeal depression were tallied as one swallow. The proposed parameters are the standard guidelines to inspect and interpret the timed test of swallowing.[16] The test order was randomized and each participant had 6 h intertest interval to avoid training effect and fatigue.

Data analysis

Applying the two online data, a total of three swallowing indices were calculated: (a) volume/swallow (V/S), a volumetric parameter; (b) time/swallow (T/S), a temporal parameter; and (c) swallow capacity (SC), the combination of volumetric and temporal parameters. These indices were derived using previously established formula mentioned below.[16]

V/S = 100 ml/total number of hyolaryngeal movements (ml)

T/S = Total swallow time/total number of hyolaryngeal movements (seconds)

SC = 100 ml/total swallow time (ml/seconds).

Statistical analysis

The swallowing indices were systematically tabulated and subjected to the Shapiro–Wilks test of normality using the Statistical Package for the Social Sciences (Version 17) (SPSS Inc., Chicago, IBM Corp). Repeated measures analysis of variance (R-ANOVA) was used for testing the effect of straw and cup and multivariate ANOVA (MANOVA) was performed to determine the main effect of age.

   Results Top

The data of the present study were normally distributed with P < 0.05 for HYA and HEA participants for the rim of the cup and through the straw condition, respectively, across the three swallowing indices. Mean and SD (represented as error bars) of V/S, T/S, and SC are represented in [Figure 1], [Figure 2], [Figure 3] respectively. The findings of swallowing indices are discussed below.
Figure 1: Results of descriptive statistics for volume/swallow index

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Figure 2: Results of descriptive statistics for time/swallow index

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Figure 3: Results of descriptive statistics for swallow capacity index

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Descriptive statistics


From [Figure 1], it can be observed that HYA had higher baseline volume for swallowing by the rim of the cup and HEA had higher volume for each swallow for through the straw conditions. Rest assured, comparing swallow performance between through the straw, both HYA and HEA participants exhibited better swallow performance across 7 cm × 0.5 cm followed by 7 cm × 0.25 cm, 15 cm × 0.5 cm, and 15 cm × 0.25 cm. This pattern indicates that decreasing length of the straw assists in higher intake of thin liquids.


Comparison of time taken for one swallow, which is represented in [Figure 2], suggests that HYA participants had faster swallowing time compared to HEA participants. Among HYA participants, no evident clinical difference was observed when straw length and width were modified. It was interesting to note that the least swallowing time was observed for 7 cm × 0.5 cm straw (wherein the performance dropped below the baseline condition). Contrastingly, a scattered performance was noted in HEA participants through the straw condition, with 15 cm × 0.5 cm having the shortest swallowing time followed by 7 cm × 0.5 cm, 7 cm × 0.25 cm, and 15 cm × 0.25 cm.

Swallow capacity

In the baseline condition, swallowing performance was higher in HYA participants than HEA participants and this is depicted in [Figure 3]. On the contrary, there was minimal difference between the mean values of HYA and HEA across different straw lengths and widths. Arguably, the least SC was noticed for 15 cm × 0.25 cm condition in both the test populations.

Inferential statistics

Within group

In HYA, results of the R-ANOVA were statistically significant for V/S (F {3.042, 199.629} = 23.175; P = 0.00) and T/S (F {1.769, 357.715} = 15.273; P = 0.000). No statistically significant difference was noted for SC. Post hoc Bonferroni test results for pair-wise comparison of V/S and T/S are revealed in [Table 1] and [Table 2], respectively. Similarly in HEAs, results of the R-ANOVA revealed statistically significant difference for V/S, T/S, and SC as F (2.680, 67.032) = 5.731, P = 0.002; F (3.005, 0.729) = 5.292, P = 0.002; and F (2.349, 133.817) = 16.864, P < 0.000, respectively. Bonferroni post hoc analysis results of V/S, T/S, and SC are expressed in [Table 3], [Table 4], [Table 5], respectively.
Table 1: Post hoc Bonferroni test of repeated measures analysis of variance results for volume/swallow in healthy young adults

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Table 2: Post hoc Bonferroni test results for time/swallow in healthy young adults

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Table 3: Post hoc Bonferroni test results for volume/swallow in healthy elderly adults

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Table 4: Post hoc Bonferroni test results for time/swallow in healthy elderly adults

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Table 5: Post hoc Bonferroni test results for swallow capacity in healthy elderly adults

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Between group

MANOVA statistical test was applied to note any statistical significance between HYA and HEA performance. Results of the statistical test revealed significant difference only for V/S in 15 cm × 0.25 cm (F {1, 75.522} = 7.112; P = 0.01; partial η2 = 0.129); 7 cm × 0.5 cm (F {1, 71.186} = 4.185; P = 0.04; partial η2 = 0.08); and 7 cm × 0.25 cm (F {1, 114.005} = 5.685; P = 0.02; partial η2 = 0.10). Similarly, for T/S, statistical significance was noted only for 15 cm × 0.25 cm (F [1, 2.687] = 13.201; P = 0.01; partial η2 = 0.216); 7 cm × 0.5 cm (F [1, 1.098] = 10.571; P = 0.002; partial η2 = 0.18); and 7 cm × 0.25 cm (F [1, 1.566] = 12.893; P < 0.000; partial η2 = 0.212). No statistical significance was observed between HYA and HEA for SC index. Pair-wise comparison for the statistically significant values was done by applying Bonferroni post hoc analysis and the results are depicted in [Table 6].
Table 6: Pair-wise comparison of multivariate analysis of variance between healthy young adults and healthy elderly adults

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   Discussion Top

In the present study, we had HYAs and HEAs swallow 100-ml thin liquids from the rim of the cup and four different variants of straw. Results of descriptive statistics revealed differences in swallowing from the rim of the cup with four straw variants. The difference in sequential swallowing between the cup and through the straw can be attributed to variations in mechanical properties and its subsequent impact on the physiology of swallowing.[6] When a utensil has a large rim, like what is observable in the cup, the wide diameter facilitates a higher volume of thin liquids to pass into the oral cavity compared to through the straw that has a smaller rim.[12] This would have resulted in increased V/S when the cup was used for swallowing. Consequent to this mechanism, researchers have advocated that while using straw, in contrast to the cup, healthy geriatrics give more pauses between sips to inspire air.[18] As a result, HEAs have had longer T/S compared to HYA.

Longer dwelling time is also another factor that differentiates swallowing through the straw condition across HYAs and HEAs.[11] In our study, as per [Figure 2], 15 cm × 0.25 cm straw dynamics has the shortest swallow. While increasing the straw length permits more intra straw dwell time, decreasing the width provides scope for increase in sucking to draw in the water to the straw. Nevertheless, earlier, straw was used as an effective strategy for individuals with oral spillage as it aides in tight lip seal and increases muscular effort.[19] The results observed in the study are supportive of previous established reports.[19]

Comparing the performance of rim of the cup with Indian normative(s), our study participants performed 7-ml and 3-ml below par in HYAs and HEAs, respectively, for V/S; clinically similar for T/S; and 6-ml and 5-ml lower by HYAs and HEAs, respectively, for SC.[20] In another study by Thejaswi et al., HYAs drank from the rim of the cup at 17 ml/s, which is a better swallowing performance compared to our study. Lower performance illustrated in the study must be considered as a normal variation(s) in swallowing and not pathological. To some extent, our study emulates the works of Veiga et al.[8] Equating our results of swallow capacity with their elderly adults, our study participants had increased consumption by 4 ml/s and 3 ml/s for the rim of the cup and straw, respectively. The major contributor for the difference by straw swallow is the 21 cm × 0.5 cm straw style used by Veiga et al., which is longer than the current research methods with 15 cm × 0.5 cm straw style.[8] Differences in swallow indices also reflect varied methodology and instruction for water swallowing test, which is a common observation by researchers.[21] In the aforementioned study, Rai directed the participants to swallow 150-ml quickly, and in our study, we adopted a different test volume (100-ml) and instruction set (swallow in their natural style).[20] With regard to swallowing through the straw condition, to our knowledge, there is a dearth of studies in the Indian community and hence there is no data available for comparison.

The effect of ageing on swallowing physiology can be explained by the well-accepted “Law of Least Effort” that states “individuals can voluntarily alter the effort in food consumption by varying the sip volume.” Adopting this viewpoint, we state “due to ageing, HEAs would already have anticipated difficulty in swallowing 100-ml lukewarm water.” This awareness could drive HEAs to adapt their swallowing style by using straw as a compensatory strategy, wherein straw increases intra-dwelling time and decreases swallow capacity. Therefore, the amount of thin liquids being swallowed is cut down, which in turn decreases the risk for swallowing difficulty. This could also reason out geriatric population preferring to use straw for drinking thin liquids.[6]


The present study has its limitations. First, the participants' experience in using straw was not controlled. This could be deleterious by means of inducing an external practice effect. We minimized the role of practice effect by randomizing the trial and avoiding multiple trial attempts prior to data collection. Second, the study did not consider middle-aged adults. Having this age group could have created scope for deriving any trend in swallowing physiology that would arise with increase in age. Another drawback was the testing swallowing ability using thin liquids' consistency only in lukewarm condition. Conventionally, 100-ml water and/or timed test of swallowing involves thin liquid in room temperature; however, it is ideal to test drinking with straw across different consistencies and temperatures for wider clinical applications. Considering the fact that straw is universally used to drink commercially available packed thin liquids, the study would have used different taste (sweet, sour, bitter, etc.). Straw insertion depth and pressure to suck the thin liquids were not controlled in the study, and the potential influence of this on the study results remains a question.

   Conclusions Top

The present experiment provides empirical evidence of differential swallowing performance with straw and through the cup. Healthy geriatrics swallow using cup yielded higher quantity of volume intake in a longer time compared to their younger peers. However, SC index was similar in HYAs and HEAs. The result of the present study cues straw to be an effective strategy in healthy geriatrics to attain better control over thin liquids. Increasing the straw length and decreasing the straw width are expected to decrease swallow performance and this straw permutation is expected to permit less quantity of bolus ingestion that in turn could facilitate safe swallowing. Further studies are warranted exploring the effect of sequential swallow on a large sample size and in clinical population.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]


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