4. Discussion
Assessing macronutrients’ distribution for the whole Spanish population, but also by sex and age, is important for health policy makers. Moreover, the detailed information on dietary sources for macronutrients is critical to better understand the strengths and weaknesses of diet quality. Despite that secular trends in energy intake remaining stable or even decreasing in many European countries, including Spain, the partitioning of the macronutrient distribution is worsening and somewhat moving away from the recommendations and traditional Mediterranean dietary pattern, as shown in the present ANIBES study. Although the negative changes affect all age groups and either males or females, those are less pronounced as age increase.
In the ANIBES study, overall protein intake was well above the upper recommended limit (15% Energy (E)) [
21]. The dietary reference intake for total protein is about 0.8 g/kg body weight for adults, representing roughly 12% of energy intake [
21]. The Spanish National Survey of Dietary Intake, the Encuesta Nacional de Ingesta Dietética España (ENIDE) study or trends observed in the Spain Food Consumption Survey (FCS) results were also equivalent [
22,
23]. Protein intake, regardless of sex or age group, was higher when compared to the updated dietary reference intakes for the Spanish population [
20] (e.g., 54 g/day in adults and older adult men; 41 g/day in adults and older adult women) or those previously published by the European Food Safety Authority (EFSA) in 2012 and revised in 2015 [
24]. In fact, only 10% of the ANIBES population (P10) would be within the recommended range for dietary protein intake. However, if we refer to the acceptable range proposed by the Institute of Medicine [
25] for protein intake (10%–35% E), our results would be within the limits.
The importance of accurately defining the amount and quality of protein required to meet nutritional needs is well recognized at present, but describing how protein should be distributed (total and in terms of quality and sustainability) in food ingredients, whole foods or mixed diets is, as well.
EFSA has recently (2015) launched an updated Scientific Opinion on Dietary Reference Values (DRV) for protein, which includes typical intakes of protein for children and adolescents from 20 countries in Europe and from 24 countries in the case of the adults [
24]. Differences in methodology and age classification make comparisons difficult. However, an overview shows that average protein intake ranges in children from 29 to 63 g/day, increasing to 61–116 g/day in adolescents, being higher in males in both age groups. In adults, average protein ranges from 67 to 114 g/day in men and from 59 to 102 g/day in women. Our findings from the ANIBES study show a mean intake of 74 g/day, also much higher in males and increasing with age, except for the elderly [
24].
Data from food consumption surveys show that the actual mean protein intakes of adults in Europe are at, or more often above, the population reference intake (PRI) of 0.83 g/kg body weight per day [
24]. In Europe, adult protein intakes at the upper end (90th–97.5th percentile) of the intake distributions have been reported to be between 17% E and 27% E. It is widely accepted that an excess of protein may counteract an adequate energy profile and a healthy dietary pattern. However, when consideration has been made to derive an upper level for protein, insufficient available evidence has been reported. The Institute of Medicine, in fact, reported very high protein intakes (up to 35% E) without negative effects [
25]. The latter meaning that approximately an intake of twice the reference intakes should be considered safe in adults. This, however, must not be considered as adequate to achieve a healthy diet. In our Spanish ANIBES population, the protein intake distribution shows an inadequate high amount consumed, except for the elderly women. It should be necessary to keep in mind that when intakes are usually higher than 45% E, acute adverse outcomes may be expected.
The potential problem in association with long-term excess of protein would be, among others, how to maintain the nutrient density. On the other hand, it has been also postulated that a high increase in protein intake may favor a decrease in body weight and adiposity. However, these observations need to be well proven, since the mentioned effects may be also due to the concomitant modification of carbohydrate and/or fat intakes [
26,
27,
28]. Most of the literature, however, has concluded that there is strong and consistent evidence that when energy intake is controlled, the macronutrient proportion of the diet is not directly related to weight loss [
29]. Other potential adverse effects due to high protein intake are in relation to insulin sensitivity and glucose tolerance, with somewhat contradictory results [
30,
31,
32]. The dual effect for protein intake may be seen also for its association with calcium and bone health: it is widely accepted that protein deficiency may increase the risk of bone fragility and fracture [
33], whereas an increase in protein intake could also be associated with higher urinary calcium excretion [
34]. Finally, and more importantly, intervention studies in humans have not shown remarkable effects of high protein intake on markers of bone health [
35,
36].
Although animal sources of proteins, including meat, poultry, seafood, milk and eggs, are the highest quality proteins, plant proteins may be also an excellent and complimentary source of proteins, mainly when mixed diets include combinations, such as legumes and grains, as is widely recommended. As collected by EFSA [
24], in most European countries, the main contributor to the dietary protein intake is meat and meat products, followed by grains and grain-based products and milk and dairy products, contributing all together to about 75% of the protein intake. At that point (2011), meat and meat products represented a 32% contribution to dietary protein in Spain, much lower when compared to countries, such as Ireland, Poland or France. The trend seems to be stable in our country, since our ANIBES data show a similar percentage contribution. A marked and rapid increase for this food group has been shown in Spain in the last few decades [
16,
22], zooming out from the traditional Mediterranean diet where meat consumption used to be scarce. No significant changes in the last few years are observed in Spain for grains and grain-based products (by the way, the lowest contribution within Europe), whereas a decreasing trend in milk and dairy products and in fish and shellfish is clearly observed in recent years.
In the ENIDE study in Spain [
22], most protein intake was also of animal origin (80%) and mainly from meats (31%), although fish (27%) was also a major contributor and much higher than its contribution in the present ANIBES study. It should be taken into consideration, however, that a sharp decline in fish consumption has taken place in recent years in Spain, which may compromise nutritional goals, especially among younger populations [
23]. As mentioned, the FCS also showed a high protein intake (twice the PRIs) for the adult Spanish population in the last few years, mainly from meat and meat products (29.9%), followed by milk and milk products (16.6%), grains (16.5%) and fish and shellfish (11.3%) [
23]. In conclusion, more efforts are needed to lower the excessive and nutritionally unnecessary amount of protein consumed by the Spanish population at present, but also to redistribute the animal/plant protein ratio.
Total fat intake should be higher than 15% E to provide the intake of the essential fatty acids and energy and to be able to facilitate the absorption of lipid-soluble vitamins. In general, with moderate physical activity, a 30% E from fat intake is recommended, and up to 35% in the case of a high physical activity level [
25]. We show, however, that total fat intake in Spain is well above these recommendations and upper limits in some of the most sedentary societies, such as the Spanish society, nowadays. Interestingly, there is evidence that moderate fat intake (<35% E) is accompanied by reduced or adequate energy intake, and therefore, body weight control, moderate weight reduction and/or prevention of weight gain may be better achieved. However, EFSA has concluded that there is insufficient scientific evidence to define a lower threshold intake or tolerable upper intake level for total fat [
37]. Presently, at the European level, but also from the World Health Organization (WHO) and Food Agriculture Organization (FAO), a lower boundary for the reference intake range of 20% E and an upper boundary of 35% E have been proposed [
38]. In addition, it is well known that two main processes contribute to the development of ischemic heart disease: atherosclerosis and thrombosis. The type of dietary fat may contribute to both. Since some fatty acids have a greater role, consequently, the evaluation of updated dietary sources of fat may be a helpful tool to advise healthy dietary patterns to prevent cardiovascular diseases. Fats and oils are also important sources of essential fatty acids and some bioactive compounds of nutritional interest (e.g., polyphenols from olive oil). However, high-fat diets may decrease or impair insulin sensitivity and may be also positively associated with increased higher cardiovascular risk [
39,
40].
It is also important to understand how the different food and beverage groups and subgroups contribute to the quality of dietary fat, namely SFA, MUFA and PUFA, including n-6 and n-3 fatty acids, since dietary fat quality is markedly related to the etiology and/or prevention of different chronic degenerative diseases.
The intake of SFA has been generally recognized to be deleterious and therefore its determination is included in most of the diet quality indexes [
41]. In contrast, higher consumption of MUFA and PUFA has been reported to be associated with reduced CVD risk. The minimum recommended level of total PUFA consumption to lower LDL-C and total cholesterol, increasing HDL-C concentrations in order to decrease the risk of CHD events, is 6% E. Our present data show that this level is easily achieved by the Spanish population as a whole. In contrast, higher risk of lipid peroxidation may occur with high (>11% E) PUFA consumption, although this does not seem to represent a risk in our population findings [
25].
For infants in Europe, average intakes of SFA are usually higher than the recommended upper limit [
37]. In adults, average SFA intakes according to the last available European Nutrition Health Report [
13] vary between less than 9% E and 26% E, with the lowest values mostly observed in southern European countries. The SFA intake in the ANIBES study was also above the recommendations for all age groups and both sexes, a negative trend that is being observed in the last two decades [
23]. However, no dietary reference intakes have been set at present, nor upper levels [
37,
38]. Even so, the WHO/FAO have recommended a maximum intake of 10% E for SFA [
38], which also agrees with the Spanish Federation of Food, Nutrition and Dietetic Societies (FESNAD) Consensus Document on Dietary Fats and Oils for the Adult Spanish Population [
41]. There is also evidence from dietary intervention studies that decreasing the intake of products rich in SFA and being replaced with products rich in
n-6 PUFA (with no change in total fat intake) were effective in decreasing some cardiovascular events [
42,
43,
44]. In the ANIBES study, >70% of SFA were obtained almost equally from meat and meat products, milk and dairy products and oils and fats. In children and adolescents, the highest contribution corresponded to the sausage and meat derivatives subgroup, followed by bakery and pastry; in adults and older adults, however, olive oil and meat ranked as the primary individual contributors. These trends, again, add difficulties at present to following the Mediterranean dietary patterns for the Spanish population, which is mainly of concern in the youngest.
Available combined data for MUFA intakes in Europe range between 8% E and 11% E in infants and mostly between 10% E and 13% E in children and adolescents [
37]. In adults, the highest mean intake has been found in Greece (22%–23% E); in other European countries, average intakes vary between 11% E and 18% E. As for MUFA intake in the present ANIBES results, oils and fats were the major contributors, of which olive oil accounted for a high proportion. Undoubtedly, the latter is still one of the main strengths of the present Spanish diet, and all efforts are made to convince all age groups about its benefits for a better adherence to the Mediterranean diet. Despite this, large differences were observed across the different age groups, with olive oil contributing roughly 30% in children and adolescents, but nearly 50% in the older adult population. In our ANIBES population, MUFA intake was slightly higher in the older adult group and lower among children and adolescents, once again showing a better adherence to the principles of the traditional Mediterranean diet in the adult and senior populations. The most recent 2011 goals developed by the Spanish Society of Community Nutrition (SENC) [
21] recommend that MUFA should contribute >20% E of total energy, whereas the FAO/WHO have recommended a MUFA intake of about 16%–19% E [
38]. In contrast, an EFSA panel [
37] proposed in 2010, however, not setting any dietary reference value for MUFA based on the following criteria: MUFA are synthesized by the body, with no known specific role in preventing or promoting diet-related diseases and are therefore not indispensable constituents of the diet. This assumption by EFSA, however, is rebuttable because MUFA are present in most tissues’ cells and have roles as key compounds to maintain membrane fluidity and diverse enzymatic activities [
45]. In addition, MUFA may lower both total and LDL plasma cholesterol levels, potentially lowering also cardiovascular risk [
46]. Moreover, in the Prevention with Mediterranean Diet (PREDIMED) intervention study [
47], intake of virgin olive oil (MUFA at 22% E) was associated with much lower risk of CVD events and total mortality. Therefore, according to the PREDIMED findings, a MUFA intake target of 20%–25% E (with virgin olive oil as a main source) has been proposed. At the population level, the latter may be quite difficult to achieve.
In spite of the well-known metabolic effects of various dietary PUFA [
43], EFSA has proposed not to formulate a dietary reference value for this fatty acid family [
37]. Other organizations, such as the WHO/FAO in 2010 [
38] and SENC (2011) [
21], have suggested that PUFA should contribute 6%–10% E and 5% E, respectively. In the present ANIBES study, PUFA contributed roughly 6.6% E, with no sex or age differences, whereas
n-3 PUFA intake expressed as the percentage of energy intake was 0.63% E for the ANIBES study population and increased with age. The WHO/FAO [
38] have recommended a minimum intake for adults of 250 mg/day for
n-3 long-chain PUFA and up to 2 g/day to help prevent CVD. For European children, average cis
n-6 PUFA intakes in absolute amounts vary between approximately 5 g and 17 g per day (in the present ANIBES study, values were 12.0 ± 4.8 g/day in children and 12.6 ± 5.8 g/day in adolescents), with a much lower contribution for older adults (9.0 ± 5.3 g/day).
As for total PUFA food sources in the present study, as expected, oils and fats were also the primary contributors: olive oil was the greatest individual contributor, mainly in adults and seniors Interestingly, meat ranked first in the older groups for n-6 fatty acid intake, whereas sausages and other meat products ranked first among the youngest groups. The fish and shellfish food group was the main contributor to n-3 fatty acids only in older adults (31.4%) and adults (25.9%), but ranked second to meat and meat products in both children and adolescents. Once again, more efforts are necessary in children and adolescents to avoid the loss of some key principles of the healthy Mediterranean dietary pattern as derived from these ANIBES updated results.
WHO/FAO Expert Consultation [
48,
49,
50] recommended initially that total carbohydrate (CHO) in the diet should provide 55%–75% E. Later, the same institutions suggested a new lower limit, 50% E, whereas EFSA in Europe proposed a range between 45% and 60% E. Finally, in Spain, the SENC recommend 50%–60% total energy [
21]. The Spanish population, however, is well below the lower limit, which is considered a bad indicator of present diet quality.
Mean total carbohydrate intake was 185.4 ± 60.9 g/day (37.8 g/day min; 450.3 g/day max) and higher in men than in women. Higher total carbohydrate consumption was observed in the younger groups as compared to adults and older adults. Total sugar intake was also quantified: 76.3 ± 33.9 g/day (79.5 ± 36.6 g/day in men, 73.0 ± 30.6 g/day in women). Differences were also seen according to age group with significantly higher intakes in children and adolescents compared to those observed in adults and older adults.
In the latest EFSA Scientific Opinion on DRV for CHO and dietary fiber, data were presented for children and adolescents in 19 countries and for adults in 22 countries in Europe [
50]. Even though there is a large diversity in the methodology used and age classification, as stated, the highest mean intakes were observed in the Czech Republic and Norway, whereas the lowest were found in Greece and Spain. As for fiber, average dietary intakes varied from 10 to 20 g/day in young children and from 15 to 33 g/day in adolescents, whereas in adults, it ranged from 15 to 30 g/day. Finally, for the elderly, most of the countries showed intakes from 20 to 25 g/day.
It is well known that dietary CHO shows a variety of physical, chemical and important physiological properties: control of body weight, diabetes, CVD, large bowel cancer, constipation and resistance to gut infection, caries and a low density of micronutrients, among others. In addition, to judge the quality of the diet, it is crucial to distinguish the different types of CHO and dietary sources, as shown in the present study; the latter since the main interest and concern are associated with the content of sugars (natural or added) and fiber, glycemic index, refined
vs. whole-grains, the presence of fruits and vegetables or solid
vs. liquid CHO [
49,
50].
CHO provide energy and can contribute to weight gain, being overweight and obesity when consumed in excess. Intervention studies have provided evidence that high fat (>35% E), low carbohydrate (<50% E) diets are associated with adverse short- and long-term effects on body weight, although the data are insufficient to define a lower threshold of intake for carbohydrates [
51,
52]. It is also known that frequent consumption of sugar-containing foods can increase the risk of dental caries [
53]. However, the available data do not allow for setting an upper limit for the intake of added sugars on the basis of risk reduction for dental caries, which has not yet been proposed. Evidence relating a high intake of sugars (mainly added sugars)
versus starches to weight gain is also inconsistent and controversial [
54]. As a consequence, according to EFSA, the available data are insufficient to set an upper limit for added sugar intake [
50], even though there is some evidence that high sugar intake (>20% E) may increase serum triglyceride and cholesterol concentrations and might adversely affect serum glucose and insulin levels, but this is still insufficient to set an upper limit for added sugar intake. The latter, however, does not exclude that food-based dietary guidelines and nutrition goals should take into account potential negative effects under certain conditions and reinforce the importance to limit sugar consumption. More strongly, a new WHO guideline [
55] recommends that adults and children should reduce their daily intake of free sugars to less than 10% of their total energy intake according to their daily dietary energy reference intakes. A further reduction to below 5% has been proposed to potentially provide additional health benefits [
55]. In this sense, the percentage of energy from sugars in our study was 17.0% E for the total population, significantly higher in females compared to males, and was more marked among the oldest participants, which shows that better educational campaigns and advice for the Spanish population is further needed. Paradoxically, secular trends of CHO intake in Spain show an inverse association with Spanish people affected by being overweight/obesity at all ages. Importantly, a diet high in fiber is usually considered also to have relatively low energy density, the promotion of satiety and a lower degree of weight gain. The percentage contribution of carbohydrates has steadily decreased since the 1960s in Spain. In that decade, the energy profile was in line with the recommendations [
22]. It is remarkable also that when dietary fiber intake in Spain in the 1960s was much higher than the present data from the ANIBES study, the prevalence of excess weight was also quite lower. The current and increasing worsening is linked to a decline in the consumption of cereals and derivatives, legumes and pulses and potatoes. However, as expected, cereals and derivatives represent the highest contribution to total carbohydrates, followed by milk and derivatives. Whole-grain cereals, vegetables, legumes and fruits are the most recognized sources for dietary CHO due to their additional high content in fiber and low energy content. As derived from our present data, whole-grain cereals and legumes are consumed in lower amounts than recommended.