onsumed less than the EAR for magnesium. In addition, 25.6% of females reported intakes that provided less than the EAR for iron, although the majority of iron intakes were from heme protein sources (i.e., chicken, hamburger, other beef and pork).
The finding of high sodium, phosphorus and vitamin A intakes in the setting of insufficient intakes of other key micronutrients emphasizes the need for medical students to learn how to optimize the nutrient density of their daily intakes. Certain simple additions or substitutions could be recommended that are likely to yield significant improvements. For example, substituting foods from the legumes group (i.e., dry beans, peas and lentils) as protein sources in main meals and adding various types of nuts and seeds as between-meal snacks would be a relatively easy strategy to better balance dietary intakes and a potential solution to improving the intakes of vitamin E as well as folate, iron, calcium, magnesium, potassium, fiber and protein . Students could also be taught to make intentional choices regarding their staple foods such as selecting calcium-fortified orange juice and cereals that are folate-fortified and high in fiber.
While foods and beverages are the preferred sources of micronutrient intakes because of the variety, synergy and bioavailability of nutrients provided, the present data suggest that inadequate total food intake may be a problem in this population. In light of this concern, multivitamin multimineral (MVM) supplementation may be another strategy to close the gap between intakes and requirements . Consistent with prior literature , the present data showed that about half (51%) of students in each cohort reported taking MVM regularly for an average of three years. For supplement users, total folate, vitamin E, vitamin D, calcium, magnesium and iron intakes were significantly greater than non-supplement users (all Ps < 0.001). Thus, supplement use increased total micronutrient intakes to levels that met the respective nutrient reference values, except for vitamin E which remained deficient in 14% - 28% of students in each cohort.
In interpreting these data, some limitations should be noted. The data were not collected from a random sample but rather a convenience sample of medical students.
While it is possible the findings might differ in the group of students who did not respond to the survey, the demographics of the responders are consistent with a recent nationally representative survey  and the findings from these students agree with larger and more representative investigation of medical students’ energy and nutrient intakes . Secondly, like most methods of dietary assessment, all of the data are self-reported; it is possible that using a reduced-length FFQ allows underor over-reporting of energy and nutrient intakes by as much as 20% . However, the actual reporting error rate in medical students overall and those sampled herein is unknown. Thus, it would not be possible to reliably correct for potential error rate in the present study . Notably, the Block FFQs are widely used, have been tested in numerous populations, and the data collected are strongly associated with reference measures of intakes
. Moreover, using the FFQ allowed investigation of the absolute, unadjusted levels of micronutrient intakes, and thus, how much of each micronutrient subjects consumed (i.e., in millior micrograms). By doing so, comparison to the Dietary Reference Intakes was performed, as opposed to assessing only percentages or percentiles of intakes . The other strengths of this study are the consistency of data collection methodology over several years and the assessment of important dietary factors that have not been previously reported in this population.
This is the first comparison of the specific micronutrient intakes of students enrolled in a US medical school to the Dietary Reference Intake values. The main finding was that dietary intakes were especially low in male and female students for key nutrients related to maintaining health and preventing chronic disease, that is, folate, vitamin D, vitamin E, calcium, magnesium, potassium and iron. Insufficient dietary intakes for these specific nutrients were consistent across all students in all years and lower than demographically-matched population-based data [51,52]. It is notable that only 25% of males and 22% of females reported consuming more than 2 servings of fruits per day. Likewise, only 23% of males and 19% of females reported consuming 3 or more servings of milk and dairy products per day. Even with the increased number of daily vegetable servings observed in female cohorts across the six years, vegetable intakes did not meet most recent guidelines which suggest consuming twice as many vegetable servings as previously recommended to achieve adequate intakes of the variety of vitamins, minerals and other micronutrients necessary for maintaining health .
Inadequate or excessive intakes of micronutrients can lead to various disorders. For one example, vitamin D deficiency combined with inadequate calcium intakes predisposes persons to demineralization of the skeleton which leads to osteomalacia, bone loss, osteopenia and/ or osteoporosis . In addition to bone health, vitamin D may also have a role in risk for certain types of cancer and type 2 diabetes. For another example, iron, folate and vitamin B12 cause varying forms of anemia . While the occurrence of macrocytic anemia from folate or vitamin B12 deficiency is rarer than iron deficiency anemia, folate intake is also crucial for prevention of neural tube defects, a serious consideration for women of reproductive age, such as those studied herein. Other functions of suboptimal B vitamin intake, including the role on plasma homocysteine concentration and development of cardiovascular disease continue to be investigated. Moreover, inadequate micronutrient intake (ie, vitamin A, vitamin D, the B vitamins, calcium, iron and zinc) may be associated with increased adiposity, a major public health concern as obesity is epidemic worldwide .
The reasons for the micronutrient inadequacies identified herein are likely multi-factorial and may include the significant time constraints inherent in the medical school environment , the high level of stress in that environment that has the potential to affect appetite and eating behaviors , financial considerations that may influence food purchasing patterns , as well as perceptions of body image that may limit the quantity of foods consumed . Clearly, further investigation is warranted to elucidate the determinants of the dietary practices of medical students, as well as other health care professionals.
Nevertheless, the findings from this study may be used to design practical interventions for medical student populations to help them improve their dietary intakes, especially to improve the balance of micronutrients consumed, which may serve to reduce risk for development of chronic disease in these young adults. These data may also be used to enhance the nutrition education content of the medical school curriculum, possibly using publicly available tools such as those produced under the Nutrition Academic Award Program . Ultimately, the goal is to stimulate greater awareness among medical students of their dietary intakes—not only to identify their personal dietary imbalances, and thus, improve their food selection choices to better meet public dietary recommendations, but also to enhance their preparedness as future healthcare providers so they are better able to identify and meet the nutrition needs of their patients.
The authors thank Charles D. Keil and Jessica Landsgesell, RD for assistance with data analysis and manuscript preparation.
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