Effects of Gluten-Free Diet on Food Intake of Second-Year Bachelor of Nutrition Science Students

In today’s world, diet has become an important part of one’s life. Food is related to a person’s well-being. High or low levels of specific macronutrients can lead to different types of problems. Different diets have different impacts on different bodies.

Gluten is a part of protein family called prolamins (glutenin and gliadin) which are the storage parts of protein in the starchy endosperm of many grains like wheat, barley and rye. A gluten-free diet as the name suggests is a diet containing no gluten in it. It refers to removal of all the grains which contain gluten in them.

Gluten-free diet has gained a large amount of popularity amongst general population. The consumption of gluten-free foods has increased over the last thirty years. People with coeliac disease have an intolerance to these grains. The intake of gluten by people with coeliac disease results into inflammation in the gut and pain. It is a global disease and the only available treatment for it is gluten-free diet. The avoidance of gluten has also made people believe that it can bring health benefits to them. Any restrictive diet results in nutritional inadequacy amongst people who do not have any problems. Consumption of a gluten-free diet primarily affects the grain intake. It can possibly result into nutritional deficiencies like fiber, folate, iron and some other micronutrients or nutrient excess like saturated fats.

This study aims to find the effects of a two-week gluten-free diet on number of serves of different food groups consumed by second year nutrition science university students. The data was self-reported by referring to the Australian Guide to Healthy Eating recommended serves list.

Methods

A randomized control trial was performed to see effects of a two-week gluten-free diet on 84 university students from NUT2002 unit of second year of Bachelor of Nutrition Science course at Monash, Clayton campus. Participants were randomly assigned to either intervention or control group, based on their student ID numbers picked out of a hat to reduce the risk of bias. Participants who had personal reasons contacted the unit coordinator to get allocated in their preferred group but everyone else was randomly allocated to the study groups.

Ethical Approval

This study was approved by Monash University Human Research Ethics Committee. All the participants were explained about a written consent form before participating in the study. It was compulsory for all the participants to sign up the consent form before getting involved in the study.

Study Design

The participants following both the diets were asked to report their demographic information like age, living arrangements and disposable income at the start of the study and were made to report their intake of food intake including vegetable and legumes, fruits, grains, meat, poultry, fish, dairy and discretionary foods based on the Australian Guide to Healthy Eating recommended serves at baseline and follow up. Also, participants had to record their weight at baseline and after two weeks to report the weight and BMI change. All of this data was self-reported by the participants by adding in their collected information on google docs to share it with the cohort.

Diet

Participants in the intervention group were given knowledge about which foods they can or cannot eat in the form of a lecture and a guided group discussion was held on the diet. The control group was instructed to follow up their regular diet as normal.

Outcomes Measured

The data was analyzed by using IBM SPSS. It was tested for normality and based on it either parametric T-test or nonparametric (the Wilcoxon rank sum test) was going to be used for data analysis. All p-values in the analysis were two tailed and under 0.05 (p £ 0.05) which were considered as statistically significant. The Wilcoxon rank sum test was used to analyze the data of one variable on two events (baseline and follow-up).

Results

The study sample consisted of 84 students out of which only 73, 35 from control and 38 from gluten-free diet, reported the complete data. The study was conducted for two weeks.

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Place Order

The age was presented as 1 labelled as 25 years and under and 2 labelled as over 25 years. ‘1’ was used as living with family, ‘2’ living on campus, ‘3’ living alone and ‘4’ others was presented in numbers mentioning about the participant’s living arrangements. Disposable income was presented as ‘1’ for income above $50 or more per week and ‘2’ for less than $50 per week. Weight and BMI change was noted at baseline and follow up and only the change between the two was reported in the data. The demographics data was non normally distributed because of which median and interquartile ranges are presented. The outcome of evaluating the weight and BMI change after following the diet was to see if following gluten-free diet would result in reduction or addition in weight of the participants. Participants following gluten-free diet gained some weight and had a little increased BMI. Whereas there was no change seen in control group.

Both the study groups reported data on the number of serves consumed following the gluten-free or the control diet. The intake of number of serves of different food groups including vegetable and legumes, fruit, grains, meat, poultry and fish, milk, cheese, yoghurt and discretionary food items was noted by the participants at baseline (day 1) and follow up (day 14) of the diet. The data was non normally distributed as to why medians and interquartile ranges are displayed. Also, to compare the variable’s value on two different events which was baseline and follow-up, the Wilcoxon rank test was used to get p-value. The vegetable intake for control and gluten-free diet evaluated that the p-value was 0.03 for both the groups, meaning that there is some significant difference and the null hypothesis is rejected. Also, the intake of grains for both the study groups show p-value 0.05, which means that there is no statistical significant difference between these variables. The medians of both study groups in baseline and follow up show similar results. The results for both the study groups were quite similar to each other except the grain intake.

Discussion

This study aimed to find the effects of a two week gluten-free diet on number of serves of different food groups consumed by second year nutrition science university students. During this two weeks of study, thirty eight university students who followed the intervention diet, i.e. gluten-free diet consumed an adequate amount of vegetables and legumes ranging from 4-5 serves. The intake of fruits met the daily recommended number of serves. The consumption of grains dropped down considering that six serves should be consumed according to the Australian Guide to Healthy eating. The intake of meat was adequate, meeting the recommendations. The dairy intake was near to the recommended serves and discretionary serves were quite adequate.

Thirty eight participants reported that they consumed about two to four serves of grains which did not meet the daily requirements.. In 2011-12, it was surveyed in Australia that the population largely consumed grains by eating foods like variety of breads, ready to eat cereals, cookies, doughnuts, pasta, flours used for baking etc. These food items contain gluten in them which people avoiding gluten cannot consume. T.Thompson et al. in her study estimated the intake of grains and different nutrients from a three day food record and she concluded that grains which contain gluten in them are a good source of dietary fibre, folate, iron, niacin, riboflavin and thiamine and reduction in grain intake in people following a gluten-free diet can result in low levels of folate, iron, dietary fibre and many more nutrients in the body. The consumption of grains that do not contain gluten in them helps to meet up the recommended serves of grain intake but it does not provide with the exact same amount of nutrients that are present in gluten containing products. Also in a study of S.J Shepherd et al., they looked into a seven day food intake and Giorgia Vici et al. aimed to evaluate the nutritional quality of gluten-free diet, both these studies found that the gluten-free food items like ready to eat cereals or breads do not contain enough amount of dietary fibre as during the process of making these foods, the grain’s outer layer is removed which contains the highest amount of fibre and only the starchy inside part is used. In addition, a paper in the Journal of the American Dietetic Association reported that these food items are not enriched or fortified because of which people consuming gluten-free food suffer with low levels of folic acid, iron and B-vitamins in their body.

The study of university students showed an adequate amount of vegetable, legumes and fruits consumed in both study groups. In 2014-15, it was found that almost half population (49.8%) above the age of 18 years in Australia consumed their recommended serves of fruit whereas only 7% of the population met the vegetable guidelines. Vegetables and fruits are naturally gluten-free foods, an increased intake was expected to see in this food group as these foods provide a good amount of fibre and other vitamins and minerals. Since, the grain intake was less, higher intake of fruits and vegetables would help to meet the dietary fibre requirements as the recommendations are set if a person is consuming enough of all other food groups and since the grain intake is low which supplies a good amount of dietary fibre, the fruits and vegetables intake could have increased in participants following gluten-free diet to meet their fibre requirements. In addition, the Journal of the Academy of Nutrition and Dietetics reported that consumption of fruits and vegetables when following a gluten-free diet helps to reduce sodium intake and the urge to drink sugar sweetened beverages helping them to maintain their energy levels. This is helpful as a lot of processed gluten-free foods available in the market are high in sugar content so consumption of fruits would help in avoiding the additional sugar content from the drinks.

The intake of meat, poultry and fish was adequate in both the diets. But it is hard to say if the participants following the gluten-free diet met their recommended protein intake as the servings consumed were similar comparing both the study groups and the recommended serves are set keeping in mind about the other food groups role in providing the adequate amount of nutrients as according to J. Miranda et al. gluten is present in the primary protein of wheat flour and its removal from the diet would result in low amounts of protein content in the body. The protein content that people following gluten-free diet cannot consume from grains should consume from increasing their meat, fish and poultry intake a little as to supply their body with adequate amounts of protein.

The consumption of dairy products met the recommended serves approximately. But according to a study it was found that people following a gluten-free diet tend to consume less dairy products resulting in deficiency of calcium and vitamin D which further results in high risk of osteoporosis found by two studies.

The intake of discretionary foods was within the recommended range of serves inn both study groups. This was expected as the participants are Nutrition Science students of second year and they would consume a healthy diet. Whereas according to Mallika Marshall of Harvard Medical School, the variety of gluten-free foods in the market are made with a lot of sugar and fat to make them taste good. She also claimed that by consuming these products instead of other whole foods, nutritional deficiencies could arise resulting into more serious health problems which can be seen in people who consume convenient foods.

The limitation of this study is that there could have been some university students who followed gluten-free diet before participating in this study and got randomly allocated towards the control study group which would result in consuming a gluten-free diet but being a part of control group. Also, the participants studying nutrition science may likely consume more healthier options available and not consume the discretionary foods which are gluten-free as much as the normal population which would result in adequately meeting up with the recommended serves. Also, complete and correct collection of data could be improved. It resulted in elimination of some participants leading to a reduced sample size with only seventy three participants in total, thus leading to a reduced chance of a proper population representation. However, the focus on a specific group allows better and closer observation of a healthy population. The time duration for the study of two weeks may have influenced food choices of participants and they may require more time to give better results. Information about participant’s ethnicity would have helped to understand more about the food habits of the study group as university is a diverse place and university students participating in the study would consume different types of foods resulting in different aspects contributing to the number of serves consumed by a person. An example in context of this can be Asian people consume a lot of rice and since it doesn’t contain gluten, their grain intake would be higher whereas people from other backgrounds who don’t consume rice would have lower serves of grain.

Further, research is required to develop a strong believe that if consuming a gluten-free diet is beneficial for people who are not allergic to gluten. Improvements can be made to adjust the limitation of this study.

Conclusion

In summary, the results indicate that gluten-free diet resulted in decreased serves of grains but did not affect any other food group intake. This can lead to some nutritional risk factors. To achieve better results, the study should be done on a bigger set of people representing different ethnicities in future. It is better to consume gluten containing foods if a person does not have any allergies as they are enrich in nutrients that are very beneficial for our body.