This is the first study to provide a comprehensive overview of the dietary intake of adolescent girls living in the Dakar region, Senegal. Although healthy foods represented more than half of their total dietary intake, on average, their daily consumption of unhealthy foods, as well as their intakes of fats and sodium, were high. Differences in weekday and weekend dietary intakes were also noted. Specifically, mean intakes of calcium and zinc were higher on the weekend than on weekdays, while the opposite was observed for sodium. Our findings also show that while intakes of healthy foods were higher than that of unhealthy foods, fibre, iron, and calcium intakes remained inadequate while intakes of other nutrients such as zinc and vitamins A and C appeared to be sufficient. Most of the healthy foods consumed by adolescent girls came from the grains / tubers/ roots, and plantains food group. The adolescents also consumed moderate amounts of foods from the meat/poultry, andfish and egg groups but low amounts of milk and dairy products. The daily consumption of fruits and vegetables was also below WHO’s recommendation. Despite eating foods from a variety of food groups, the daily consumption of foods among adolescent girls did not generally meet the recommended EAT-Lancet reference for a healthy diet. Nevertheless, some positive behaviours were observed in the majority of adolescent girls such as drinking water, eating three meals a day, and having breakfast.
Energy and nutrient intake
In our study, adolescents consumed an average of approximately 2550 kcal per day, which is in line with the estimated energy requirements for girls in this age group, regardless of physical activity level. Energy requirements for adolescents aged between 14 and 17 years old vary from 2075 kcal (considering a low level of physical activity) to 2875 kcal (high level of physical activity) . In contrast, a study among children and adolescents (5–19 years old) conducted in 2010 in the Dakar region found that the mean daily energy intake was 1400 kcal . This difference in energy intake may be partially explained by the inclusion of both children and adolescents in Fiorentino et al.’s study. These differences may also reflect a change in food behaviours among adolescents due to the increase in the number of street food and fast food outlets in the Dakar region over the past decade . However, our results are similar to Dapi et al.’s findings who reported a mean daily energy intake of 2297 kcal among adolescent girls (n = 119) living in urban Cameroon .
In terms of macronutrient intakes, the most concerning finding was that adolescents in our study consumed, on average, 110 g of fats per day. These findings are well above those of Keats et al.  who reported that the mean daily intake of fats was 36 g among 15–19-year-old adolescent girls living in Africa. Our findings are also slightly higher than those reported by Dapi et al.  and Napier & Hlambelo  who found that adolescent girls in urban Cameroon consumed 70 g of fat  and those in South Africa consumed 75 g . Also, about 40% of the total daily calories consumed by adolescents in our study came from fats, a proportion that is slightly higher than the 30% reported by Fiorentino et al.  and Dapi et al.  as well as the 34% observed in Napier et al.’s  study . The proportion of the total energy intake from saturated fats was also above WHO’s recommendation of 10%  for the majority of adolescent girls. This high intake of saturated fats may be related to our finding that 78% of girls reported eating fast foods daily, with a mean intake of 150 g per day, as these tend to contain high quantities of saturated fats. These findings are worrisome as an excessive intake of fats, particularly in saturated fats, increases adolescents’ risk of becoming overweight or obese and of developing chronic diseases in adulthood, such as cardiovascular diseases . However, it must also be noted that monounsaturated and polyunsaturated fats accounted for approximately 70% of the adolescents’ fat intake. This finding is encouraging as consuming foods that are rich in monounsaturated and polyunsaturated fats, such as canola oil and olive oil, have been found to have beneficial effects on lipid profile and blood pressure, and to reduce inflammation and oxidative stress [40, 41].
On average, adolescents in our study had an intake of only 15 g of fibre per day, which is well below the recommended daily intake of 25 g . It is also well below the 30 g previously observed among adolescent girls in urban Cameroon  although similar to the intake (17 g) reported by Napier & Hlambelo  in South Africa. In fact, 98% of adolescents had insufficient intakes of fibre, which is slightly higher than the proportion (88%) reported by Fiorentino et al. . Our findings may be partially explained by the low intake of fruits and vegetables. Similar to previous findings [4, 8], only 46% of adolescent girls consumed fruits and vegetables every day. Therefore, promoting fruits and vegetables is important, not only to provide essential micronutrients to their diet but also to increase their intake of fibre.
As previously mentioned, iron deficiency in LMIC has been well documented, and our findings add to this body of literature. In our study, the average daily iron intake was 10 mg, which is well below the recommended daily nutrient intake of 30 mg for a diet with 10% bioavailable iron . Among our sample, 82% of the adolescent girls were at risk of inadequate iron intakes, as compared to Fiorentino et al.’s study which reported that 55% of children and adolescents had insufficient iron intakes. Among adolescent girls, Dapi et al.  estimated that approximately 50% of them had iron intakes that were below the EAR. In our study, the high proportion of adolescent girls who were at risk of inadequate iron intakes may be attributed to the moderate consumption of iron-rich foods from the meat/poultry and, fish and eggs groups. The mean daily average intake of foods from these two groups combined was only 100 g. It is worth noting that there were large variations in intakes of these foods. For example, only 14% of adolescent girls reported having consumed eggs over the 3 days while 50% reported eating, on average, more than 90 g of meat/poultry and, fish during the same period. Our findings may also be partially explained by the iron bioavailability reference used in this study. Specifically, to estimate the prevalence of insufficient iron intake, a diet with 10% of iron bioavailability was considered as the reference in our study, as recommended by WHO / FAO / UNU . However, adolescents in our study may have had a diet that more closely resembled that of a western diet with a 15% iron bioavailability given that the mean intake of iron-rich foods was around 100 g. When considering such a diet, 50% of adolescent girls would have an insufficient iron intake. This proportion would be similar to that of Fiorentino et al.  who used 18% of iron bioavailability as a reference to estimate the proportion of insufficient iron intake among urban Senegalese school-aged children and adolescents. Nevertheless, adolescents are likely at risk for iron-deficiency and iron deficiency anemia which are both the leading causes of adolescent disability-adjusted life years among girls aged 10–19 .
Compared to Fiorentino et al.  who found that 79% of children and adolescents (10–17 years old) had insufficient intakes of vitamin A, this proportion was only 23% in our study. While lower than Fiorentino et al.’s  findings, this proportion is in line with Dapi et al.  who found that only 18% of adolescent girls in urban Cameroon had insufficient intakes of vitamin A . Despite a limited consumption of vegetables (which are rich sources of vitamin A), our finding was not surprising considering the frequent use of vegetable oil, which contains 200 μg RE of vitamin A / 100 g, which is used for cooking local dishes. Moreover, oil fortification with vitamin A became mandatory at the end of 2009 , which was a few months before Fiorentino et al.’s study was undertaken. This may also explain the difference between their results and ours. Additionally, in our study, some (n = 8) adolescents benefited from dishes prepared with red palm oil which is an excellent source of vitamin A. In fact, the mean daily consumption of oils and fats in our group was 57 g (± 92 g) which provides an intake of approximately 114 μg RE. The significant consumption of fortified oils by adolescents may also have contributed to the high energy intake from fats.
Results from our study showed that 54% of adolescents had inadequate intakes of vitamin C, as compared to 53% in Fiorentino et al.’s study and 35% in Dapi et al.’s study. As with fibre, this finding is most likely due to the low consumption of fruits and vegetables, which are the main sources of vitamin C.
Zinc intakes appeared to be adequate to meet adolescents’ nutritional requirements. While foods that are rich in zinc, such as meat, poultry, and fish, are often also rich sources of iron, our study found that 55% of adolescents had a zinc intake that was below international recommendations, as compared to 24% for iron. Therefore, it is likely that other food sources of zinc contributed to adolescents’ intake, such as grains products (which includes millet), legumes (such as “niebe”), and dairy products.
Similarly to iron, calcium intake was problematic as almost all adolescent girls had an insufficient intake. This finding is similar to those of Fiorentino et al.  and Dapi et al. . The low consumption of milk and dairy products may explain this finding which has also been reported in South Africa by Napier & Hlambelo . This situation is concerning as it may jeopardize adolescent growth and increase the risk of osteoporosis later on in life.
The mean sodium intake on weekend days and weekdays was well above the 2 g limit recommended by WHO & FAO . Two-thirds of adolescents had intakes that exceeded this threshold. Similar to fat intake, the high sodium intake may be attributed to the consumption of fast foods and some condiments. Also, 93% of adolescents were having at least one meal outside their home, which was usually lunch during school days. This may partially explain the higher sodium intake during weekdays. This meal most often consisted of a sandwich prepared with white bread (the French baguette) and onion sauce (prepared with bouillon cubes which contain large amounts of sodium), to which meat, green peas, French fries, or canned mackerel were added. This excessive and chronic intake of foods and dishes rich in sodium is particularly worrisome given the increased risk for hypertension later in life .
Despite there being differences in zinc, calcium, and sodium intakes between weekend days and weekdays, no differences were observed for food groups. It is possible that the slight (although not significant) increases in consumption of cereal, milk, dairy products, and condiments were enough to impact these intakes. This could have lead to statistically significant differences for those nutrients but not for food groups.
Our findings showed that grains / roots / tubers and, plantains were the main food group consumed by adolescent girls and that rice was the most consumed food in this group. This finding is not surprising as rice is the staple food in Senegal. It was not uncommon for large quantities of white rice (up to 750 g per meal) and white bread (up to 100 g of the “French baguette”) to be eaten either at lunch and/or dinner, daily. Given the large quantities of grain-based dishes consumed, these foods contributed a significant amount of calories to the adolescents’ diet. It is worth noting that both rice and plain white bread were both categorized as healthy foods in our study. Therefore, it is very likely that these foods contributed to our finding that adolescent girls consumed more healthy than unhealthy foods. This said, using fibre content as an additional criterion to classify foods may have provided a better picture of the quality of healthy foods that were consumed.
Recent UNICEF data  revealed that worldwide, 42% of adolescents in LMIC consumed carbonated soft drinks at least once a day. Consumption of sugary drinks was also common in our study, with 25% of adolescents interviewed reporting that they consumed sugary drinks daily. High consumption of sugary drinks has been identified as problematic, not only because of the high content of sugar but also because of the possibility of them replacing more healthy beverages such as water and milk. Only 2% of adolescents in our study consumed milk and dairy products daily, which is similar to findings from Keats et al.’s review  that showed that only 6% of African adolescents consumed milk and dairy products daily. This said plain water was still the beverage of choice among adolescents in our study.
It is important to note that our study did find that adolescents were engaging in some healthy behaviours, such as having breakfast, eating three meals a day, and drinking plain water. Moreover, while most were having breakfast and eating three meals a day, these were often taken outside the home. Therefore, these meals may have been of lower nutritional quality .
Lastly, the dietary pattern of adolescent girls participating in our study was very different from that of the EAT-Lancet reference for a healthy diet. For example, their diet was high in refined grains and processed foods including sweets. Adolescent girls should be encouraged to adopt the EAT-reference for a healthy diet as it could help prevent malnutrition and chronic diseases while also preventing environmental deterioration and human death .