Grape polyphenols have shown a promising role in the modulation of metabolic syndrome (MetS), mostly in animal models. However, clinical studies are scarce and they usually only consider a fraction of polyphenols, ignoring the non-extractable polyphenols (high molecular weight compounds or associated with macromolecules such as dietary fibre). This study aimed at evaluating the effect of grape pomace, rich in both extractable and non-extractable polyphenols, on markers of MetS. Fifty subjects (22 women) aged 20–65 with at least two MetS factors were randomly assigned to the product (daily dose of 8 g of dried grape pomace) or to the control group in a 6 week crossover design with a 4 week wash-out. Samples were collected at the beginning and at the end of both periods; half of the participants were subjected to an oral glucose tolerance test at the beginning and the end of the supplementation period. Grape pomace supplementation significantly improved fasting insulinaemia (p < 0.01), without affecting other cardiometabolic risk parameters. A tendency towards an improvement in postprandial insulinaemia was observed, particularly in those subjects with higher fasting insulin levels. Therefore, supplementation with grape pomace may be a strategy for improving insulin sensitivity in subjects at high cardiometabolic risk.

Purpose: To determine serum fatty acids of lacto-ovo vegetarian (LOV), vegan (VEG) and omnivorous (OMN) adults, and to analyse the effects of consuming a docosahexaenoic acid (DHA) supplement of vegetable origin on fatty acid profile. Methods: A randomized, double-blind, placebo-controlled crossover design was conducted in healthy adults. Volunteers (n = 116) were randomly assigned to a DHA-supplement (dose 250 mg/day), made from the microalgae Schizochytrium sp., or a placebo during 5-week periods separated by a 5-week washout interim period. Compliance and dietary intake were estimated and serum fatty acids were determined by gas chromatography. Results were analysed by mixed linear models. Results: Percentage of linoleic acid (C18:2n6) in serum was the highest among the fatty acids in the three diet groups, followed by oleic (C18:1n9) and palmitic (C16:0) acids. Linoleic (C18:2n6) and alpha-linolenic (C18:3n3) acids were higher in VEG compared to OMN (p < 0.001), while in LOV, their levels were intermediate between the other groups. Women presented higher DHA (C22:6n3) than men (p < 0.001). The DHA-supplement increased serum DHA compared to placebo in the three diet groups (p < 0.001), and a higher increase was observed in VEG followed by LOV (p < 0.001). The ratio serum n-6/n-3 improved by the supplementation but remained higher in LOV and VEG than in OMN. In contrast, the DHA-supplement decreased docosapentaenoic (C22:5n3) and docosatetraenoic (C22:4n6) acids in all diet groups (p < 0.001) and increased the eicosapentaenoic to alpha-linolenic fatty acids ratio (p = 0.016). Conclusion: The DHA-supplement at dose of 250 mg/day was effective in increasing serum DHA either in omnivorous, lacto-ovo vegetarian and vegan adults. Clinical trial registration: Registered at Clinicaltrials.gov (www.clinicaltrials.gov), NCT04278482.

Plant-based diets are becoming increasingly popular, and scientific information concerning the nutritional status in this population is needed. This study determined the fatty acid profile of Spanish lacto-ovo vegetarians (LO-vegetarians) and vegans. Participants were 104 healthy adults, LO-vegetarians (n = 49) and vegans (n = 55). Lifestyle habits and consumption of food and omega-3 supplements were estimated by questionnaires. BMI, blood pressure, and abdominal and body fat were determined. Serum was collected to analyze fatty acids, glucose, lipids, homocysteine, insulin, and leptin. Volunteers were classified according to serum omega-6 to omega-3 (n-6/n-3) ratio into three groups: n-6/n-3 < 10, n-6/n-3 ≥ 10 to 20, and n-6/n-3 > 20. Results showed low cardiovascular risk and high insulin sensitivity with negligible differences between diet types. Linoleic acid (C18:2n-6) was the major serum fatty acid, followed by oleic (C18:1n-9) and palmitic (C16:0) acids. In contrast, serum eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3) were (median, interquartile range) 0.27, 0.18% and 1.59, and 0.93%, respectively. Users of n-3 supplements (<10% of total vegetarians) had significantly higher EPA than non-users, while frequent consumption of flax-seeds was associated with increased α-linolenic acid (C18:3n-3). However, neither n-3 supplementation nor food consumption affected DHA levels in this vegetarian population.

Vegetarian diets may compromise iron status, as they provide non-haem iron which has low bioavailability. Spanish lacto-ovo vegetarians (n = 49) and vegans (n = 55) were recruited and haematological and biochemical iron parameters were analysed. Food and supplements consumption, body composition, physical activity, menstrual blood losses and hormonal contraceptive use were assessed. Four groups were studied: Iron deficiency anaemia (IDA), iron depletion (ferritin 30 ng/mL). IDA was uncommon (n = 5, 4.8%), 27.9% of participants were iron-depleted, and 30.8% were iron-deficient. Serum ferritin was lower in women than men (p < 0.001) and IDA and iron depleted individuals were all women. There were no differences attributed to diet type, time being vegetarian or physical activity. The menstrual period length was negatively associated with transferrin saturation (ρ = −0.364, p = 0.001) and hormonal contraceptive use (ρ = −0.276, p = 0.014). Iron supplements were consumed most frequently by IDA and iron-deficient subjects (p = 0.031). Conclusions: Iron status did not vary between lacto-ovo vegetarians and vegans and there was not an influence of the time following a vegetarian diet. Although men were iron-sufficient, iron deficiency was frequent in women, who should apply strategies to increase iron bioavailability, especially if they experience intense menstrual blood losses.

Consumption of vegetarian diets in Spain coexist with the culture of the Mediterranean diet. This study shows that Spanish lacto-ovo vegetarian, vegan, and omnivorous present similar low cardiometabolic risk.

Sustainable healthy diets are promoted, and consequently vegetarian diets are currently increasing. However, scientific information on their effects on bone health is scarce. A cross-sectional study was performed in adults (66% women) classified into three groups: omnivores (n = 93), lacto-ovo vegetarians (n = 96), and vegans (n = 112). Nutrient intake, body composition, physical activity, vitamin D status (25-hydroxycholecalciferol, 25-OHD), parathormone (PTH), and bone formation (bone alkaline phosphatase, BAP) and resorption (N-telopeptides of type I collagen, NTx) markers were determined. Lacto-ovo vegetarians and especially vegans showed lower protein, fat, calcium, phosphorous, vitamin D, retinol, iodine, and zinc intakes, and higher carbohydrate, fibre, carotenes, magnesium, and vitamin K intakes compared to omnivores. Body composition was similar in the three groups that performed vigorous physical activity regularly. Body bone mass and muscle mass were positively correlated with BAP, and time performing physical activity with 25-OHD. The prevalence of vitamin D deficiency or insufficiency (25-OHD < 75 nmol/L) was 93.7% in the studied population, and vitamin D deficiency (25-OHD < 25 nmol/L) was significantly higher in vegans. Vegetarians of both groups had increased PTH and NTx with vegans showing significantly higher PTH and NTx than omnivores. Conclusion: Adult vegetarians, especially vegans, should reduce the risk of bone loss by appropriate diet planning and vitamin D supplementation.