The main aim of the present study was to assess the dietary intake of Spanish recreational cyclists and triathletes. The main finding was that a large proportion of the present sample consumed an unbalanced diet, characterised by excess protein, and CHO and vitamin E deficiencies. A high proportion of triathletes who reported regular supplementation, demonstrated an excessive vitamin B3 intake. On the other hand, cyclists tended to belong to a group of individuals characterised by fibre, calcium, zinc, iodine, magnesium, and vitamin B1, B9 and D deficiencies, in addition to poor lipid quality.
Mean total CHO intake was 246.0 ± 88.1 g/day. This is slightly higher than the 185.4 ± 60 g/day reported in previous studies with Spanish populations16. However, findings uncovered by the present study (46.8%±7.1), represent values that are still below the lower limit of 50%-60% total energy recommended by the SENC17. The American College of Sport Medicine recommends that CHO intake should range from 6 to 10 g/kg of BM for athletes3. This is due to the fact that carbohydrate maintains blood glucose levels during exercise and replaces muscle glycogen. In the present study, participants average CHO consumption amounted to 3.5 ± 1.4 g/kg of BM in general and was higher in woman (4.2 ± 1.6 g/kg of BM) than in men (3.4 ± 1.4 g/kg of BM). Another study with non-elite athletes competing in endurance sports showed that between 23 and 54% of athletes did not consume the recommended amounts of CHO18.
Total fat intake should constitute more than 20% of total energy intake. Failing to reach this intake could impede correct absorption of lipid-soluble vitamins, whilst failing to provide sufficient essential fatty acids3. When engaging in moderate physical activity, 30% of energy from fat intake is recommended. This increases to 35% when engaging in high physical activity19. Values reported in the present study met SENC recommendations that total fat intake should account for 30–35% of total energy20. Similar results have been reported for the Spanish population with a total fat intake of 78.7 (26.5) g/day in 18-64-year-old adults16.
With regards to the quality of fats, in 201021 WHO/FAO recommended a maximum intake of SFA of 10% of total energy due to the association between SFA consumption and cardiovascular disease risk22. PUFA consumption should fall within a range of 6–11%, whilst MUFA intake can account for up to 15–20% of energy from total fat intake. Results from the ANIBES study in Spain showed SFA intake to be above recommended levels regardless of age and sexes16, with similar trends also emerging across most countries23. A healthier SFA intake (10.0 ± 2.5%) was found in the present sample of recreational Spanish athletes. It has been suggested that MUFA induces a protective effect against metabolic syndrome and cardiovascular disease risk factors24. Further, PUFA, especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), has been recommended for its potential benefits for human health25. In the present study, MUFA and PUFA intake was within recommended ranges (14.8 ± 3.5% and 6.4 ± 1.8, respectively), although slightly higher percentages were found in women than men. In general, these results are similar to the results reported in the ANIBES study16, however, this previous study did not find sex- or age-related differences.
In the present study, overall protein intake was well above current recommendations for the Spanish adult population, which stipulates an upper limit of 15% of total energy20, or a total protein intake of about 0.8 g/kg BM. Similar trends were observed by the Spanish National Survey of Dietary Intake26 and the European Food Safety Authority in 201227. The present study also showed higher protein intake than that recommended by the American Dietetic Association of Canada and American College of Sports for endurance athletes (1.2 to 1.4 g/kg BM/day)3. Protein is a crucial macronutrient for providing substrates for the repair and remodelling of muscle and body proteins28. In the present study, males reported the upper limit of this recommendation, whilst females exceeded this by consuming 1.7 ± 0.5 g/kg BM/day. A diet that is high in protein and low in CHO is not only typical in Western countries but typical of professional athletes in many different countries29–30. Individuals who consume this type of diet risk suffering metabolic acidosis, which can negatively impact athletic performance6.
The intake of all vitamins and minerals exceeded their respective RDA or AI, with the exception of vitamins D and E and, in some cases, calcium. Exercise stresses many of the metabolic pathways where micronutrients are required and exercise training may result in muscle biochemical adaptation that increases micronutrient needs. The most common vitamins and minerals of concern to athletes are calcium and vitamins D, C, E and B complex, alongside iron, magnesium and selenium31. Our study showed an excess of all of the above apart from vitamins D and E. Vitamin D is required for adequate calcium absorption and bone health20. However, as vitamin D is not only obtained from the diet but can also be obtained through sun exposure, vitamin D inadequacy may be diagnosed by evaluating serum total 25-(OH)-vitamin D. Low vitamin E intake is common within European and US populations and could be the result of the low stability of this vitamin in vegetable oils32.
Supplements are commercially available products used to complement the normal diet through the provision of additional vitamins, minerals, amino acids, etc33. Supplements are normally used because of the ergogenic effects of the vitamins or minerals they comprise on recovery from exercise and health8. However, consumers tend not to use this product for their intended purpose and they are not compatible with normal eating habits34. To our knowledge, this is the first research study to examine the prevalence of supplementation in recreational endurance athletes whilst also considering the two different sporting disciplines of cycling and triathlon. The proportion of participants that reported often taking supplements in our study is much lower than that reported in other studies with professional athletes35–36. The majority of participants who took supplements, opted to take protein, multivitamins, minerals and omega-3. A certain degree of supplementation can be justified. For instance, some women may supplement with iron. Iron deficiency can impair muscle function and limit work capacity, resulting in impaired training adaptations and poorer performance37. However, other supplements, such as multivitamins, are recommended only when deficiencies are present and only under professional supervision8. Nonetheless, a number of previous studies have shown that athletes most frequently consume multivitamins and mineral supplements without supervision, instead using them indiscriminately at their own discretion38. Protein supplementation also seems to be inappropriate as many participants already exceeded guideline amounts of protein through their regular diet alone.
The present study revealed a group of participants who tended to be triathletes, supplemented often and consumed an excessive amount of vitamin B3. Excessive vitamin B3 intake could provoke flushing, headaches, light-headedness, itching, nausea and vomiting. In addition, liver injury can occur in rare cases and progress to fulminant hepatic failure39. As the indiscriminate use of vitamin and mineral supplements may adversely affect physiological function and impair health40, it is recommended to consume high nutrient density food rather than nutritional supplements. Another group, mostly formed of cyclists, was characterised by deficiencies in vitamin B9, D and B1, in addition to calcium, zinc, iodine, magnesium and fibre deficiencies. Further, lipid quality within the cluster was generally poor. Even though a high percentage of the overall sample reported high micronutrient intake in general, we found a cluster of mostly cyclists whose consumption was less than the required amount. Perceptions that supplements could substitute a well-balanced diet may explain these deficiencies.
A limitation of the present study is its cross-sectional design, which inhibits examination of casual relationships. Further, measurement error is an inherent risk of self-report questionnaires. However, the FFQ has previously demonstrated high validity and reliability within similar populations. Height and weight were self-reported as opposed to directly measured due to time, financial resources and manpower constraints. While this method is less accurate than direct measurement, it has demonstrated good agreement and validity in healthy weight populations.