Vegetarian people do not eat meat (including fowl) or seafood, or products containing these foods. A lacto-ovo vegetarian eating pattern is based on grains, vegetables, fruits, legumes, seeds, nuts, dairy products, and eggs [1
]. Epidemiological studies on vegetarians show that appropriately planned vegetarian diets are healthy and nutritionally adequate [1
]. Compared to omnivorous diets, vegetarian diets can provide several health benefits [6
]. However, these positive health-related outcomes in vegetarians can be influenced by factors other than dietary practices. A healthy life-style, including regular physical activity and the avoidance of harmful practices such as smoking and drinking, are some of the influencing factors [10
]. To date, most studies compared a self-selected vegetarian group with standard population references [1
]. In order to truly attribute the health advantages associated with a vegetarian life-style to the dietary pattern, it is necessary to compare the vegetarian subjects with an adequate reference sample. The matched samples principle uses samples of subjects that have been matched to eliminate individual differences and that are respectively subjected to the control and the experimental condition [11
]. In such a design, every vegetarian subject is compared with a non-vegetarian subject matched for possible confounding factors.
It was the aim of this study to compare the nutritional intake between 106 vegetarians (V) and 106 matched non-vegetarians (NV). Matched samples were formed based on the following parameters: sex, age, body mass index (BMI), physical activity, tobacco use and alcohol consumption.
Studies have pointed out that the effect of a vegetarian diet and a higher intake of plant based food sources may be social class specific [21
]. In this study, both groups had a high educational level, although the V subjects had an even higher educational level compared to the NV subjects. As it is the case in most of the study designs with self selected subjects, a possible selection bias regarding to the most health conscious ones (V and NV) and the most convinced vegetarians may have occurred. A possible explanation for the differences in educational level between these matched samples can be found in a study of Gale et al.
(2007), who concluded that vegetarianism may be viewed by those of higher intelligence as a healthier option than consuming meat and that higher scorers for IQ in childhood are associated with an increased likelihood of vegetarianism in adulthood [23
]. Results demonstrate that the energy requirement surpasses the energy intake. No significant differences were found between the energy intake of the V and the NV, for both genders. As reported in other studies [24
], underreporting of energy intake and over reporting of physical activity may be a possible explanation for the discrepancies between energy intake and energy requirement in both V and NV subjects. The discrepancies between energy intake and energy requirement were of the same magnitude for the V and the NV despite a different method for the estimation of the physical activity level. However the Baecke questionnaire and the FPACQ are validated methods for the estimation of the PAL [17
]. As no “gold standard” exists to estimate energy intake and requirement, a food record diary and the physical activity level may be considered the best possible way of matching these two samples [24
]. Both V and NV subjects met the reference values for protein intake (with the exception that the NV women had slightly too high protein intake). However, the V had a significantly lower intake of proteins when compared to the NV, for both the men and women. A vegetarian diet suggests a higher intake of plant-based protein sources. An issue that is still unclear is whether all sources (plant based or animal) have the same impact on disease outcomes. A study of Keleman et al.
] indicated that plant proteins have a more protective effect against coronary heart disease mortality compared with animal proteins, whereas no clear association with cancer incidence and mortality was observed for any subtype of protein. Other studies suggest that the higher protein consumption from animal sources is responsible for an acidifying effect in omnivores, which may increase the risk for compensation from the calcium sources of the body [13
Carbohydrate intake of both the V men and women is significantly higher when compared to the NV group. Carbohydrates should deliver 55-75 E% of the total energy intake with no more than 12 E% originating from mono- and disaccharides (except when originating from high fruit consumption) and the rest from polysaccharides [20
]. Both male and female V subjects had a high mono- and disaccharide intake, while NV subjects had an intake around 12 E%. However, this higher intake can be explained by higher fruit consumption in plant-based diets. A more in depth analysis on a subsample of these groups (V and NV) showed a higher fruit and vegetables intake in the V (respectively 283 ± 60 g/day and 268 ± 45 g/day) compared to the NV (120 ± 65 g/day and 185 ± 38 g/d, respectively) [13
]. The V subjects had a significantly lower intake of total and saturated fat when compared to the NV, for both the men and the women. In addition, the results of the V are closer to the Belgian RDA than the results of the NV. Studies suggest that a lower dietary intake of saturated fat in V contributes to a reduction of ischemic heart diseases [7
]. The higher saturated fat intake and lower poly unsaturated fat intake in the NV results in a better poly unsaturated fat/saturated fat ratio in V [20
]. Appleby et al.
] found a significantly inverse association between dietary fiber and BMI, and a significant positive association between animal fat intake and BMI. Alewaeters et al.
] suggested that the lower BMI values in the vegetarian sample compared with the Belgian references may be a result of a healthier diet. Even with groups matched for BMI, a higher fiber intake and a lower saturated fat intake was found in the V compared to the NV subjects.
Significant differences in mineral intake were found between the V and the NV subjects. Sodium intake was lower in V men, and potassium, calcium and magnesium intake was higher in V women. Zinc and iron intake was higher in both V men and women. These minerals are often described as critical in a vegetarian diet [1
]. Most of the iron intake in a vegetarian diet is non-heme iron, which is more difficult to absorb compared to heme-iron. However, the higher iron intake in the V combined with a plant-based diet, commonly rich in vitamin C, may improve the iron absorption [32
]. β-carotene intake was higher in the V, whereas vitamin A intake was higher in NV. The vitamin C intake was comparable and met the RDA. The health aspects of daily fruit and vegetables intake are sustained by several epidemiological studies. Fruit and vegetables may protect against excessive weight gain because of their low energy density, high fiber content, low glycemic index and for bone health because of their alkaline-forming properties [33
]. As reported in the Dietary Approaches to Stop Hypertension study, the blood pressure lowering effect of a vegetarian diet may be due to a high potassium and magnesium content delivered by fruit and vegetables [35
]. Our results in the female vegetarians corroborate this finding.
In most studies it is difficult to disentangle the effect of other health benefits due to the vegetarian diet as a result of other health related behaviors. However, in this study of matched samples-where V and NV were similar with regard to a wide variety of physical, lifestyle and social factors-the V appear to consume a diet closer to the Belgian RDA compared to the diet of the NV. These results corroborate the findings of the Belgian national food consumption survey where similar dietary habits were found in NV subjects. It was concluded that an improvement of the Belgian food pattern, which is mainly an omnivorous diet, is necessary for a better prevention of diet-related diseases [36
]. We can conclude, within the limits of our sample, that the results of this study suggest that the vegetarian diet consumed in this group is adequate to sustain the nutritional demands in a better way than the omnivorous diet. This indicates a possible contribution of a vegetarian or mainly plant based diet to an improvement of the Belgian food pattern for a better prevention of diet related diseases [1
]. The care to ensure that a vegetarian diet is well planned has been recognized in many professional instances [1