Plant-based meat and dairy analogues contain less protein than their animal-based counterparts and rely on various plant protein sources, which frequently display incomplete amino acid (AA) profiles that do not reflect dietary requirements due to low quantities of one or more essential AA (EAA). There is little insight in the AA profiles of most of these plant-based analogues. We assessed the AA composition of 40 plant-based meat and dairy analogues that were commercially available in The Netherlands in March 2023, and compared their EAA profile to dietary requirements and to the EAA profile of their meat and dairy counterparts. Total protein contents were lower in most analogues when compared to their animal-based counterparts (meat analogues, n = 16 (80%); lunch meats and cheese analogues, n = 10 (100%); milk and yoghurt analogues, n = 9 (90%)) and accompanied by lower EAA contents. In reference to dietary requirements, the sum of the total EAA contents was adequate in all but one of the analogues. Nevertheless, all analogues displayed deficiencies in one or more specific EAA. Methionine contents were most frequently low (n = 39; 98%), followed by lysine contents (n = 11; 28%). Essential AA compositions varied between analogues irrespective of the protein source(s) used. In conclusion, plant-based meat and dairy analogues exhibit incomplete EAA profiles, which may compromise adequate protein nutrition in plant-centered diets.

Malnutrition is a significant issue among older New Zealanders, with 24% malnourished and 35% at high risk(1). Oral nutritional supplements (ONS) are prescribed to improve nutrient intake in malnourished or at-risk individuals. Evidence supports that ONS can enhance energy and protein intake(2). However, efficacy depends on regular and adequate consumption. Fonterra Research and Development Centre sponsored a research programme of three interventions with the aim of assessing the liking, absorption, and compliance of ONS formulations (containing functional proteins at 9.6% and 14.4% w/v protein) versus commercial comparators. A feasibility study was also done to assess whether ONS could be used to fortify foods in a residential care setting. All trials received ethics approval. In study one (trial registration: NCT04397146), the palatability and satiating effects were evaluated in 104 participants. Fonterra’s 14.4% protein ONS was well-received for sweetness, creaminess, and texture, while the 9.6% protein ONS had lower palatability. Satiety levels were similar across all products. Key drivers of overall liking included smooth texture, pleasant taste, and ease of drinking. In study two (ACTRN12621000127808), a randomized, double-blind crossover trial of 18 healthy adults, the post-prandial effects of Fonterra’s formulation compared to energy and protein matched commercial products on amino acid (AA) appearance and gastric emptying were examined. Fonterra’s 14.4% protein ONS significantly increased the incremental area under the curve and peak concentration of essential and branched-chain AA, including leucine, compared to control (p<0.05). These findings suggest potential benefits for muscle mass preservation in at-risk patients. In study three (ACTRN12622000842763), a randomized, single-blind crossover trial, 100 older adults completed compliance and tolerance assessments of Fonterra’s formulation compared to energy and 9.6% protein matched commercial product. Compliance for all three ONS was high, with mean compliance rates of 96.1% for Fonterra 9.6%, 94.5% for Fonterra 14%, and 95.2% for comparator. Palatability scores were not significantly different. Adverse events were minimal and short-lived, mainly occurring on the first day; 30-50% of participants reported tolerance issues, such as flatulence, bloating, and burping, regardless of the product. No significant differences in satiety were observed between the interventions. Lastly, a pilot study assessed the feasibility of incorporating ONS into foods in a residential care setting. The chef found the ONS easy to work with and add to desserts, which subsequently increased the protein and calcium content of main meals. Residents found the fortified desserts palatable and acceptable. This research programme supports the use of ONS assisting older adults to meet their nutrient requirements and demonstrates that formulations containing Fonterra’s functional proteins are well-accepted, effective in increasing amino acid appearance, and easily incorporated into institutional diets, with high consumption compliance and minimal adverse effects.

This study examined whether supplementation with collagen peptides (CP) affects appetite and post-exercise energy intake in healthy active females. In this randomised, double-blind cross-over study, fifteen healthy females (23 (sd 3) years) consumed 15 g/d of CP or a taste matched non-energy control (CON) for 7 d. On day 7, participants cycled for 45 min at ∼55 % Wmax, before consuming the final supplement. Sixty-min post supplementation an ad libitum meal was provided, and energy intake recorded. Subjective appetite sensations were measured daily for 6 d (pre- and 30 min post-supplement) and pre (0 min) to 280 min post-exercise on day 7. Blood glucose and hormone concentrations (total ghrelin, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY), cholecystokinin (CCK), dipeptidyl peptidase-4 (sDPP-4), leptin, and insulin) were measured fasted at baseline (day 0), then pre-breakfast (0 min), post-exercise (100 min), post-supplement (115, 130, 145, 160 min) and post-meal (220, 280 min) on day 7. Ad libitum energy intake was ∼10 % (∼41 kcal) lower in the CP trial (P = 0·037). There was no difference in gastrointestinal symptoms or subjective appetite sensations throughout the trial (P ≥ 0·412). Total plasma GLP-1 (AUC, CON: 6369 (sd 2330); CP: 9064 (sd 3021) pmol/l; P < 0·001) and insulin (+80 % at peak) were higher after CP (P < 0·001). Plasma ghrelin and leptin were lower in CP (condition effect; P ≤ 0·032). PYY, CCK and glucose were not different between CP and placebo (P ≥ 0·100). CP supplementation following exercise increased GLP-1 and insulin concentrations and reduced ad libitum energy intake at a subsequent meal in physically active females.

This repeated cross-sectional study assessed the validity and reproducibility of the myfood24® dietary assessment tool against dietary intake biomarkers in healthy Danish adults. The study included 71 healthy adults (14/57 m/f), aged 53.2 ± 9.1 years with an average BMI of 26.1 ± 0.3 kg/m2. Participants were instructed to complete seven-day weighed food records using myfood24® at baseline and 4 ± 1 weeks thereafter. Estimated mean dietary intake was compared with objective measures of energy metabolism and selected dietary intake biomarkers in fasting blood (folate) and in 24-hour urine (urea, potassium). Resting energy expenditure was measured by indirect calorimetry. Application of the Goldberg cut-off classified 87% (n = 62) of participants as acceptable reporters. A strong Spearman’s rank correlation was observed between total folate intake and serum folate (ρ = 0.62). Acceptable correlations were noted for serum folate (ρ = 0.49) and urinary potassium excretion (ρ = 0.44) with estimated and measured protein intake (ρ = 0.45); energy intake and total energy expenditure (ρ = 0.38); potassium intake and potassium excretion (ρ = 0.42); and estimated fruit and vegetable intake. Reproducibility analysis revealed strong correlations (ρ ≥ 0.50) across most nutrients and food groups, except for fish and vitamin D (ρ = 0.30 and ρ = 0.26, respectively). Notably, reproducibility for folate and total vegetable intake exhibited the highest correlations (ρ = 0.84 and ρ = 0.78, respectively). In conclusion, while some limitations exist, myfood24® remains a useful tool for ranking individuals by intake, particularly in studies focusing on relative comparisons.

Major depressive disorder (MDD) is characterized by changes in appetite and body weight as well as blunted reward sensitivity (‘anhedonia’). However, it is not well understood which mechanisms are driving changes in reward sensitivity, specifically regarding food. Here, we used a sample of 117 participants (54 patients with MDD and 63 healthy control participants [HCPs]) who completed a food cue reactivity task with ratings of wanting and liking for 60 food and 20 non-food items. To evaluate which components of the food may contribute to altered ratings in depression, we tested for associations with macronutrients of the depicted items. In line with previous studies, we found reduced ratings of food wanting (p = .003) but not liking (p = .23) in patients with MDD compared to matched HCPs. Adding macronutrient composition to the models of wanting and liking substantially improved their fit (ps < .001). Compared to carbohydrate-rich foods, patients with MDD reported lower liking and wanting ratings for high-fat and high-protein foods. Moreover, patients with MDD showed weaker correlations in their preferences for carbohydrate- versus fat- or protein-rich foods (ps < .001), pointing to potential disturbances in metabolic signaling. To conclude, our results suggest that depression-related alterations in food reward ratings are more specific to the macronutrient composition of the food than previously anticipated, hinting at disturbances in gut–brain signaling. These findings raise the intriguing question of whether interventions targeting the gut could help normalize aberrant reward signals for foods rich in fat or protein.

The increasing demand for food and especially proteins leads to the search for alternative protein sources. Meat co-products, which are available but little used in human food, provide a potential solution to this challenge. The present study aimed to evaluate the nutritional quality of two beef protein ingredients (greasy greaves recovered proteins (GGRP) and water recovered proteins (WRP)), both co-products of the fat rendering process. Their true ileal digestibility (TID), digestible indispensable amino acid score (DIAAS) and kinetics of plasma amino acids (AA) were measured in ten growing pigs, each fed the two co-products and a protein-free diet. Titanium dioxide was used as an indigestible marker. Digesta samples were collected for 9 h after meal ingestion, and blood samples were collected at ten time points during the same period. Total nitrogen (N) and AA contents were determined. Data were statistically analysed using linear mixed models. The TID of total N was not different between WRP and GGRP (81–84 %, P > 0·05). The first-limiting AA was Trp for both ingredients, with a DIAAS much higher for GGRP than for WRP (74 and 10 % for adults, respectively; P < 0·001). Postprandial plasma AA concentration peaked earlier for WRP (3 h) than for GGRP (5 h). Plasma concentrations of total and essential AA were higher (P < 0·001) with GGRP diet than WRP diet. Overall, GGRP has a nutritional quality suitable to meet the needs of adults for AA, while WRP needs to be supplemented with other protein sources to fulfil the dietary requirements.

Wild relatives of crop species are known to be sources of genetic diversity that can be used in crop improvement. However, they have not always been studied adequately for the variation that may exist within them, for traits which may have important implications from an evolutionary point of view and their use in breeding programmes. In the present study, a wild groundnut species, Arachis stenosperma, has been studied for variation between accessions collected from different sites in Brazil for morphological and certain nutritional traits, and for disease resistance. Multivariate analysis of 23 characters grouped 18 accessions into two clusters, while one accession, ICG 14927, was distinct from these. However, in protein profile they all appear identical. Hence, the variation appears to have arisen in response to the climatic conditions of their habitat, which has implications for use of these accessions in breeding programmes. The variation in these traits could not be associated with any phytogeographical regions. The dispersal of this species from its centre of origin and diversity to other parts of Brazil appears to be recent and without any identifiable selection pressures having operated.

Dietary intake plays a key role in athletic performance in rowing(1). Suboptimal nutrition within the adolescent rowing population may negatively affect performance, normal growth and development, professional athlete development, and career longevity. Previous research has indicated that suboptimal carbohydrate intakes are a common issue in rowing(2). The quality of nutritional intake in adolescent rowers has seldom been explored. During moderate training, adolescent athletes should aim for 5-7g.kg-1 of carbohydrates, 1.3-1.8g.kg-1 of protein, and 20-35% energy from fat(3). This study aimed to examine the dietary intake of adolescent rowers in New Zealand and compare it with nutritional guidelines for normal growth, development, and sports performance. A cross-sectional study design involved data collection on two ‘hard’ training days, and two ‘recovery’ days from rowers (14-21 years) recruited from clubs and secondary schools around New Zealand. Participants completed four 24-hour collection periods, recording food intake, training duration and intensity. The food records were verified for accuracy, and dietary data was entered into Foodworks software for nutritional analysis. IBM SPSS software was used to calculate mean intakes for carbohydrate, protein, fat, and standard deviations. Independent t-tests were used to compare carbohydrate and protein intakes between males and females. Of the initial 40 participants, 35 fully (n = 23 females, 16.8 ± 1.9 years and n = 12 males, 17.3 ± 1.6 years) completed the study. Participants consumed 319 ± 116g (4.5 ± 1.7g.kg-1/day) of carbohydrates, 121 ± 56 g (1.7 ± 0.7 g.kg-1/day) of protein and 113 ± 46 g (1.6 ± 0.6g.kg-1/day) of fat per day. Females consumed 290 ± 80g (4.4 ± 1.3g.kg-1/day) of carbohydrates and males consumed 400 ± 78 g (5.0 ± 1.4g.kg-1/day) per day, with no significant difference between males and females intake per kilogram of bodyweight per day (p = 0.165). Minimum carbohydrate levels of 5g.kg-1 per day were only achieved by 7 females (30.4%) and 4 (33.3%) males. Females consumed significantly less protein per day, 106 ± 38g (1.6 ± 0.6 g.kg-1/day), in comparison to males who consumed 164 ± 46 grams (2.0 ± 0.5 g.kg-1/day) per day (p = 0.04). Fourteen females (60.9%) and 10 males (83.3%) consumed more than the minimum requirement of 1.3g.kg-1 of protein per day. The findings suggest that 2 out of 3 adolescent rowers in New Zealand fail to reach the minimum recommendations for carbohydrate intake(3), and males more readily meet the recommended intakes of protein when compared to females. Nutrition education for adolescent rowers in New Zealand should emphasise adequate carbohydrate and protein intakes that meet sports nutrition guidelines in order to support normal growth, development and optimised performance for these athletes.

The role of protein in decreasing the risk of cardiometabolic diseases has been proposed, yet the findings are inconsistent, possibly due to how protein intake was expressed(1). This study aimed to examine how different ways of expressing protein intake may influence its relationships with diet quality and obesity. This study used data from the Australian National Nutrition and Physical Activity Survey (NNPAS) 2011-12, focusing on adults aged ≥19 years, excluding those who were pregnant or lactating, and had both anthropometric and dietary data (n = 7637). Total protein intake was assessed by up to two 24-hour dietary recalls and reported in two measurement units, namely g/day and % of energy intake. Usual protein (g) and energy intakes (kJ) were modelled using the Multiple Source Method(2). Diet quality was assessed using the Dietary Guidelines Index (DGI)(3). Body mass index (BMI) and waist circumference were used as measures of obesity. Multiple linear regressions were performed stratified by sex, and adjusting for age, country of birth, Socio-economic Indexes for Areas, physical activity level, energy misreporting, usual energy intake (for diet quality), and non-protein energy intake (for obesity). Positive associations between protein intake and diet quality were confirmed across measurement units. Protein intake expressed in % of energy intake (β-coefficient: men = 0.97; women = 1.21, p<0.001) had a higher β-coefficient than those reported in g/day (β-coefficient: men = 0.19; women = 0.30, p<0.001). Linear regression models showed a positive association between protein intake and BMI for men and women, either expressed in g/day (β-coefficient: men = 0.02, p<0.001; women = 0.03, p = 0.001) or % of energy intake (β-coefficient: men = 0.14, p<0.001; women = 0.12, p = 0.002). The relationship between protein intake expressed in g/day and waist circumference was also statistically significant (β-coefficient: men = 0.04, p = 0.004; women = 0.05, p = 0.035). However, protein intake expressed as % of energy intake was correlated with waist circumference for men only (β-coefficient: men = 0.26, p = 0.001; women = 0.19, p = 0.075). The consistent findings across measurement units suggested that the unit of g/day and % of energy intake can be used for examining associations between protein intake and diet quality. However, associations between protein intake and measures of obesity varied between protein units and sex. These findings suggest that the selection of protein measurement units in relation to obesity outcomes might need to consider the characteristics of study population (e.g., sex, energy intake). Overall, the outcomes of this study suggest that how protein is expressed may impact the associations between protein intake, diet quality, and obesity, and therefore require further considerations when examining the role of protein in cardiometabolic health.

Protein-rich animal foods are highly digestible, high-quality sources or protein, whereas the protein quality of plant-based foods can vary considerably. Given the growing interest in alternative non-animal-based sources of protein, it is important to establish the protein digestibility of these new foods and protein concentrates which have important health implications especially for vulnerable groups who don’t consume sufficient dietary protein. The human ileostomy model is ideal for measuring protein digestibility as it enables protein digestion to be quantified independent of protein degradation in the large intestine. The aim of this study was to determine the protein digestibility and quality of a wheat-based food containing legume flours. This randomised, double-blinded, controlled cross-over intervention was conducted in 4 proctocolectomised adults with conventional and well-functioning permanent ileostomies. The study was conducted over 2 weeks and on each testing day, the participant consumed 2 test muffins (125 g each) or 2 protein-free cookies in the morning (breakfast and morning tea) followed by a standardised low-protein lunch and afternoon tea. Test muffins were made using a standard muffin recipe using wheat flour and for 2 of the test muffins 50% of the flour was substituted with soy or lupin flour. An indigestible marker, titanium dioxide was added to the muffins so that the completeness of muffin recovered in ileal digesta could be calculated. The digestible indispensable amino acid score (DIAAS) was determined by comparing concentrations of true ileal digestible indispensable amino acids to recommended amino acid requirements(1). Data was reported as mean ± SD and repeated measures ANOVA was used to compare means between treatment groups with significance reported at P < 0.05. Substituting 50% of wheat flour in muffins with soy or lupin flour doubled the protein content of muffins (soy 11.8 g/100g and lupin 10.6 g/100g) compared to muffins that only contained wheat flour (wheat 5.1 g/100g). However, substituting wheat with legume flour did not affect protein digestibility which was similar for all muffin types; wheat (76.8 ± 7.0%), soy (77.9 ± 7.4%) and lupin (81.6 ± 6.9%) (P = 0.181). The DIAAS values for all muffins were below 75% which is classified as the cut off for a good quality protein food. In conclusion, substitution of wheat-based muffins with soy and lupin flour increased the protein content of wheat-based muffins but protein digestibility and overall protein quality was similar.

This study investigates a novel early pregnancy marker in water buffaloes, focusing on RSAD2 mRNA expression, known to be upregulated by interferon-tau (IFNT) during pregnancy. While RSAD2 is primarily recognized for its antiviral effect, we hypothesized its role as a conceptus-induced component in regulating pregnancy in buffaloes. Given its differential expression compared to other IFNT-induced genes in cows, RSAD2 may serve as a biomarker for early pregnancy detection in buffaloes. RNA, cDNA, and plasma samples were obtained from archived samples collected before insemination (d0) and at d20, d25 and d40 after insemination. Twelve RNA samples, having optimal optical density and concentration, from six pregnant and six non-pregnant buffaloes were selected. The cDNA was analyzed to measure the abundance of RSAD2 mRNA using real-time quantitative PCR (RT-qPCR) and plasma for protein expression analysis using Western blot. The RT-qPCR analysis showed a transcript of RSAD2 increased significantly by 7-fold and 6-fold on d20 and d25, compared to both d0 and d40 in the pregnant group only. At d20, the sensitivity of RSAD2 was 100% and the specificity was 83.3%, and at d25-d both the sensitivity and specificity was 100%, indicating low incidences of misdiagnosing early pregnancy in buffaloes. In the non-pregnant group, RSAD2 expression remained low and did not change after insemination. Western blot analysis revealed an immunoreactive RSAD2 protein band. Densitometry analysis of the RSAD2-specific protein band, based on gray mean value, showed significantly increased expression of RSAD2 at d25 compared to d0 in the pregnant group. In conclusion, these results indicated that RSAD2 expressions at both the mRNA and protein levels show promising potential for detecting pregnancy at d25 post-insemination.

Globally, we are currently facing a rapid demographic shift leading to an increase in the proportion of older adults within the population. This raises concerns about the potential increase in age-related diseases and their impact on our ability to provide adequate health and end-of-life care. To apply appropriate interventions, understanding the changes that happen with ageing becomes essential. Ageing is often accompanied by a decrease in appetite and physical activity, which may lead to malnutrition, resulting in decreased muscle mass, physical capabilities and independence. To preserve muscle mass, older adults are advised to increase protein intake and physical activity. However, protein’s high satiating effect may cause reduced energy intake. Physical activity is also advised to maintain or enhance older adult’s appetite. This review paper aims to discuss appetite-related changes that occur with ageing and their consequences. In particular, it will focus on investigating the relationship between protein intake and physical activity and their impact on appetite and energy intake in the ageing population. Recent studies suggest that physical activity might contribute to maintaining or enhancing appetite in older adults. Nevertheless, establishing a definitive consensus on the satiating effect of protein in ageing remains a work in progress, despite some promising results in the existing literature.

The aim of this study was to assess whether adding Ca2+ to aggregate or native forms of β-lactoglobulin alters gut hormone secretion, gastric emptying rates and energy intake in healthy men and women. Fifteen healthy adults (mean ± sd: 9M/6F, age: 24 ± 5 years) completed four trials in a randomised, double-blind, crossover design. Participants consumed test drinks consisting of 30 g of β-lactoglobulin in a native form with (NATIVE + MINERALS) and without (NATIVE) a Ca2+-rich mineral supplement and in an aggregated form both with (AGGREG + MINERALS) and without the mineral supplement (AGGREG). Arterialised blood was sampled for 120 min postprandially to determine gut hormone concentrations. Gastric emptying was determined using 13C-acetate and 13C-octanoate, and energy intake was assessed with an ad libitum meal at 120 min. A protein × mineral interaction effect was observed for total glucagon-like peptide-1 (GLP-1TOTAL) incremental AUC (iAUC; P < 0·01), whereby MINERALS + AGGREG increased GLP-1TOTAL iAUC to a greater extent than AGGREG (1882 ± 603 v. 1550 ± 456 pmol·l−1·120 min, P < 0·01), but MINERALS + NATIVE did not meaningfully alter the GLP-1 iAUC compared with NATIVE (1669 ± 547 v. 1844 ± 550 pmol·l−1·120 min, P = 0·09). A protein × minerals interaction effect was also observed for gastric emptying half-life (P < 0·01) whereby MINERALS + NATIVE increased gastric emptying half-life compared with NATIVE (83 ± 14 v. 71 ± 8 min, P < 0·01), whereas no meaningful differences were observed between MINERALS + AGGREG v. AGGREG (P = 0·70). These did not result in any meaningful changes in energy intake (protein × minerals interaction, P = 0·06). These data suggest that the potential for Ca2+ to stimulate GLP-1 secretion at moderate protein doses may depend on protein form. This study was registered at clinicaltrials.gov (NCT04659902).

The interaction of cytochromes (heme proteins) with mineral surfaces is important from an environmental perspective (e.g. heavy metal remediation and reductive dehalogenation reactions), for designing biosensors and bioanalytical systems, and for emerging photovoltaic applications. In addition, the cytochrome studied here shares properties with some cytochromes from Fe-reducing bacteria and its general behavior sheds light on how other cytochromes might behave during Fe(III) reduction. The objectives of this study were to characterize the direct electrochemistry and sorption mechanism of horse heart ferricytochrome c (a mitochondrial cytochrome referred to as Hcc) on hematite surfaces as a function of pH, time of sorption and ionic strength. Hcc sorption on hematite mainly occurs between pH 8 and 10, the pH range in which hematite surfaces and Hcc are oppositely charged. Calculated net attractive forces correspond closely with the pH range of peak sorption, suggesting that sorption is mainly electrostatically controlled. Hcc sorption with ionic strength is consistent with this conclusion. The pH-dependent conformation of Hcc sorbed on hematite appears to be different from that in solution as indicated by UV-visible spectroscopy and its more negative reduction potential compared to native Hcc. Sorption kinetics were rapid and pH-independent across the pH range 3–10 with slow conformational changes occurring at >60 h. Our results suggest that the electrostatic attraction of the cytochrome towards the surface orient the cytochrome for favorable electron transfer between the heme group of the cytochrome and hematite.

Proteins and protein-like molecules are abundant in various geochemical environments; they form complexes with mineral surfaces and with dissolved organic matter. To evaluate the effect of proteins on rates of dissolution of minerals, experiments on the dissolution of amorphous silica in solutions containing various concentrations of bovine serum albumin (BSA) were performed in this study. The dissolution experiments were carried out by a batch method using solutions of 0.1 mM NaCl with 0.00, 0.05, 0.1, 0.2, 0.5, and 1.0 mg/mL of BSA at three different pH conditions, 6, 5, and 4. The results of the experiments demonstrated that BSA exhibited strong rate-enhancement effects on the dissolution of amorphous silica and were dependent on BSA concentration and the solution pH. At pH 6, the dissolution rates of amorphous silica appeared to increase successively by ~1.6, 2.2, 2.4, 2.5, and 2.9 times with increasing BSA concentrations of 0.05, 0.1, 0.2, 0.5, and 1.0 mg/mL, respectively. The rates of dissolution increased by greater degrees, ~3.1–5.8 and 4.9–13.0 times at pH 5 and 4, respectively. According to the calculated charge distributions of amino acid residues of the BSA molecule, the dissolution rates of amorphous silica were likely to be enhanced by attractive electrostatic interactions of the positively charged side chains of lysine, arginine, and histidine residues with the negatively charged >SiO− sites on the amorphous silica surface. The negatively charged side chains such as glutamic acid and aspartic acid residues may inhibit the attractive interaction, depending on the degree of deprotonation.

The extremely toxic protein, ricin, is derived from castor beans and is a potential terrorist weapon. Adsorption to clays might minimize the environmental persistence and toxic effects of this toxin. Ricin adsorption to clay minerals was measured using batch adsorption isotherms. Enzyme-linked immunoassay methods were used to quantify aqueous ricin concentrations. Montmorillonite, sepiolite and palygorskite effectively adsorbed ricin from aqueous solutions and yielded mostly Langmuir-type isotherms. The monolayer adsorption capacity from a Langmuir equation fit at pH 7 was 444 g ricin/kg for montmorillonite (SWy-2), but was only 5.6 g ricin/kg for kaolinite (KGa-1b). Monolayer capacities for sepiolite (SepSp-1) and palygorskite (PFl-1) at pH 7 were 59.2 and 58.1 g ricin/kg. The high-charge montmorillonite (SAz-1) effectively adsorbed ricin at pH 7, but yielded a linear isotherm with K = 5530 L/kg. At pH 5, both montmorillonites (SWy-2 and SAz-1) yielded Langmuir-type isotherms with monolayer capacities of 694 and 641 g ricin/kg. Clay samples with higher cation exchange capacities generally adsorbed more ricin, but adsorption also followed specific surface area. X-ray diffraction of <2 μm SWy-2 treated with 470 g ricin/kg indicated expansion up to 34.6 Å at buffered pHs of 4 and 7, but not at pH 10. Furthermore, ricin adsorption was greatest at pH 4 and 7, but minimal at pH 10. Treatment with 1.41 kg of purified ricin/kg clay at pH 5 yielded a 35.3 Å peak and adsorption of ~1.2 kg ricin/kg. Similar treatment with lower-purity ricin yielded less expansion and lower adsorption. The 35.3 Å peak interpreted either as a d002 or d001 reflection indicates a 70.6 Å or a 35.3 Å ricin/SWy-2 complex. This implies that adsorption and air drying have compressed interlayer ricin molecules by 18 to 65%. Effective ricin adsorption by montmorillonite suggests that it could be used to minimize the toxic effects of dispersed ricin.