Calcium, protein, and fruit and vegetables as dietary determinants of bone health

H. pylori infection and osteoporosis: a large-scale observational and mendelian randomization study

PURPOSE

There is controversy concerning the relationship between Helicobacter pylori (H. pylori) infection and osteoporosis. This study is to examine the causal relationship between H. pylori infection and osteoporosis and to analyze the potential mechanism underlying the relationship.

METHODS

The clinical data of H. pylori infection and bone mineral density from patients or physical examiner with good general condition in our hospital between September 2019 and September 2020 were retrospectively collected. The relationship between H. pylori infection and osteoporosis was compared and analyzed, using logistic regression to examine the potential mechanism underlying the association. To investigate the causal effects of H. pylori infection and osteoporosis, we conducted a two-sample bidirectional Mendelian randomization (MR) analysis.

RESULTS

A total of 470 patients were positive for H. pylori, with a detection rate of 52.22%. It was found that age, SBP, FPG, DBP, ALB, LDL-C, hs-CRP, and OC were positively correlated with osteoporosis, while negative correlations were observed with BMI, LYM, ALB, TP, TG, HDL-C, SCr, UA, and VitD. After stratified analysis of sex and age, it was found that there was a significant correlation between H. pylori infection and osteoporosis. The levels of SBP, ALP, FPG, LDL-C, hs-CRP, and OC in both H. pylori-positive group and osteoporosis group were higher than those in the H. pylori-negative group while the levels of BMI, ALB, TP, HDL-C, SCr, UA, and VitD in the positive group were significantly lower than those in the negative group. Logistic regression analyses with gender and age showed that ALB, FPG, HDL-C, and VitD were common risk factors for osteoporosis and H. pylori infection. In the MR analysis, the IVW results found a positive effect of H. pylori infection on osteoporosis (OR = 1.0017, 95% CI: 1.0002-1.0033, P = 0.0217). Regarding the reverse direction analysis, there was insufficient evidence to prove the causal effects of osteoporosis on H. pylori infection.

CONCLUSION

Our study provides evidence for causal effects of H. pylori infection on osteoporosis. H. pylori may affect osteoporosis through serum albumin, high-density lipoprotein, fasting blood glucose and vitamin D.

A dietary pattern rich in calcium, potassium, and protein is associated with tibia bone mineral content and strength in young adults entering initial military training

Background

Stress fracture risk is elevated during initial military training (IMT), particularly in lower-extremity bones such as the tibia. Although the etiology of stress fractures is multifactorial, lower bone strength increases risk.

Objective

The objective of this study was to assess, through the use of peripheral quantitative computed tomography, whether adherence to a dietary pattern rich in calcium, potassium, and protein before IMT is positively associated with bone indexes in young adults entering IMT.

Design

A cross-sectional analysis was performed with the use of baseline data from 3 randomized controlled trials in Army, Air Force, and Marine recruits (n = 401; 179 men, 222 women). Dietary intake was estimated from a food-frequency questionnaire. A dietary pattern characterized by calcium, potassium, and protein was derived via reduced rank regression and a pattern z score was computed for each volunteer, where higher scores indicated greater adherence to the pattern. At the 4% (metaphysis) and 14% (diaphysis) sites of the tibia, bone mineral content (BMC), volumetric bone mineral density, robustness, and strength indexes were evaluated. Associations between dietary pattern z score as the predictor variable and bone indexes as the response variables were evaluated by multiple linear regression.

Results

Pattern z score was positively associated with BMC (P = 0.004) and strength (P = 0.01) at the metaphysis and with BMC (P = 0.0002), strength (P = 0.0006), and robustness (P = 0.02) at the diaphysis when controlling for age, sex, race, energy, smoking, education, and exercise. Further adjustment for BMI attenuated the associations, except with diaphyseal BMC (P = 0.005) and strength (P = 0.01). When height and weight were used in place of body mass index, the association with BMC remained (P = 0.046).

Conclusions

A dietary pattern rich in calcium, potassium, and protein is positively associated with measures of tibia BMC and strength in recruits entering IMT. Whether adherence to this dietary pattern before IMT affects injury susceptibility during training remains to be determined. These trials were registered at clinicaltrials.gov as NCT01617109 and NCT02636348.

A comprehensive analysis of the composition, health benefits, and safety of apple pomace

Apple processing results in peel, stem, seeds, and pulp being left as a waste product known as apple pomace. This review comprehensively assessed apple pomace composition for nutritional value and bioactive substances and evaluated potential health benefits and safety. Apple pomace is a rich source of health-benefitting nutrients, including minerals, dietary fiber, antioxidants, and ursolic acid, which suggests it has potential use as a dietary supplement, functional food, and/or food additive. Preclinical studies have found apple pomace and its isolated extracts improved lipid metabolism, antioxidant status, and gastrointestinal function and had a positive effect on metabolic disorders (eg, hyperglycemia, insulin resistance, etc.). Safety studies have shown apple pomace to be a safe livestock feed additive and to have pesticide concentrations within safety thresholds established for human consumption. Commercial development of apple pomace for human consumption requires more research focusing on standardized methods of nutrient reporting, mechanistic studies, and human clinical trials.

Greater Intake of Fruit and Vegetables Is Associated with Greater Bone Mineral Density and Lower Osteoporosis Risk in Middle-Aged and Elderly Adults

Objective

A few studies have suggested that the consumption of fruit and vegetables (FV) may benefit bone health, but limited data are available in Asian subjects. We examined the association between FV intake and bone mineral density (BMD) and osteoporosis in Chinese adults.

Methods

This population-based cross-sectional study involved 2083 women and 1006 men aged 40–75 years in Guangzhou, China. Habitual dietary data was collected from a 79-item food frequency questionnaire by face-to-face interviews. The BMD was measured for the whole body (WB), lumbar spine (LS), total hip (TH) and femur neck (FN) with dual-energy X-ray absorptiometry.

Results

After adjustment for potential covariates, we observed dose-dependent associations between total FV intake and BMD and osteoporosis risk. The mean BMD was higher in tertile 3 vs. tertile 1 by 1.33% (TH) and 1.31% (FN) for FV, and 1.10% (WB), 1.57% (TH), and 2.05% (FN) for fruit (all P-trends < 0.05). Significant beneficial associations with BMD at some sites were also found in most fruit categories but not in total vegetables or their subgroups. The odds ratios (95% confidence interval) of osteoporosis (T-score ≤ −2.5) in tertile 3 (vs. 1) were 0.73 (0.58–0.92), 0.37 (0.22–0.60), and 0.71 (0.52–0.97) for FV; 0.82 (0.66–1.03), 0.48 (0.30–0.77) and 0.89 (0.61–1.12) for fruit; and 0.80 (0.64–1.01), 0.57 (0.35–0.92) and 0.76 (0.55–1.05) for vegetables at the LS, TH, and FN, respectively. The favorable association between FV intake and the occurrence of osteoporosis was evident only in subjects with lower BMI (<24.0 kg/m², P-trends < 0.05).

Conclusions

Greater intake of FV was independently associated with a higher BMD and a lower presence of osteoporosis in middle-aged and elderly Chinese subjects with lower BMI. Fruit tended to have more contribution to the favorable association than vegetables.

Life Course Dietary Patterns and Bone Health in Later Life in a British Birth Cohort Study

Evidence for the contribution of individual foods and nutrients to bone health is weak. Few studies have considered hypothesis-based dietary patterns and bone health. We investigated whether a protein-calcium-potassium-rich (PrCaK-rich) dietary pattern over the adult life course, was positively associated with bone outcomes at 60 to 64 years of age. Diet diaries were collected at ages 36, 46, 53, and 60 to 64 years in 1263 participants (661 women) from the MRC National Survey of Health and Development. DXA and pQCT measurements were obtained at age 60 to 64 years, including size-adjusted bone mineral content (SA-BMC) and volumetric bone mineral density (vBMD). A food-based dietary pattern best explaining dietary calcium, potassium, and protein intakes (g/1000 kcal) was identified using reduced rank regression. Dietary pattern Z-scores were calculated for each individual, at each time point. Individual trajectories in dietary pattern Z-scores were modeled to summarize changes in Z-scores over the study period. Regression models examined associations between these trajectories and bone outcomes at age 60 to 64 years, adjusting for baseline dietary pattern Z-score and other confounders. A consistent PrCaK-rich dietary pattern was identified within the population, over time. Mean ± SD dietary pattern Z-scores at age 36 years and age 60 to 64 years were -0.32 ± 0.97 and 2.2 ± 1.5 (women) and -0.35 ± 0.98 and 1.7 ± 1.6 (men), respectively. Mean trajectory in dietary pattern Z-scores ± SD was 0.07 ± 0.02 units/year. Among women, a 0.02-SD unit/year higher trajectory in dietary pattern Z-score over time was associated with higher SA-BMC (spine 1.40% [95% CI, 0.30 to 2.51]; hip 1.35% [95% CI, 0.48 to 2.23]), and vBMD (radius 1.81% [95% CI, 0.13 to 3.50]) at age 60 to 64 years. No statistically significant associations were found in men. During adulthood, an increasing score for a dietary pattern rich in protein, calcium, and potassium was associated with greater SA-BMC at fracture-prone sites in women. This study emphasizes the importance of these nutrients, within the context of the whole diet, to bone health. © 2016 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research (ASBMR).

Arterialized venous bicarbonate is associated with lower bone mineral density and an increased rate of bone loss in older men and women

CONTEXT

Higher dietary net acid loads have been associated with increased bone resorption, reduced bone mineral density (BMD), and increased fracture risk.

OBJECTIVE

The objective was to compare bicarbonate (HCO3) measured in arterialized venous blood samples to skeletal outcomes.

DESIGN

Arterialized venous samples collected from participants in the Health, Aging and Body Composition (Health ABC) Study were compared to BMD and rate of bone loss.

SETTING

The setting was a community-based observational cohort.

PARTICIPANTS

A total of 2287 men and women age 74 ± 3 years participated.

INTERVENTION

Arterialized venous blood was obtained at the year 3 study visit and analyzed for pH and pCO2. HCO3 was determined using the Henderson-Hasselbalch equation.

MAIN OUTCOME MEASURE

BMD was measured at the hip by dual-energy x-ray absorptiometry at the year 1 (baseline) and year 3 study visits.

RESULTS

Plasma HCO3 was positively associated with BMD at both year 1 (P = .001) and year 3 (P = .001) in models adjusted for age, race, sex, clinic site, smoking, weight, and estimated glomerular filtration rate. Plasma HCO3 was inversely associated with rate of bone loss at the total hip over the 2.1 ± 0.3 (mean ± SD) years between the two bone density measurements (P < .001). Across quartiles of plasma HCO3, the rate of change in BMD over the 2.1 years ranged from a loss of 0.72%/y in the lowest quartile to a gain of 0.15%/y in the highest quartile of HCO3.

CONCLUSIONS

Arterialized plasma HCO3 was associated positively with cross-sectional BMD and inversely with the rate of bone loss, implying that systemic acid-base status is an important determinant of skeletal health during aging. Ongoing bone loss was linearly related to arterialized HCO3, even after adjustment for age and renal function. Further research in this area may have major public health implications because reducing dietary net acid load is possible through dietary intervention or through supplementation with alkaline potassium compounds.

Diet, weight, cytokines and bone health in postmenopausal women

OBJECTIVES

To investigate diet and nutrition-related factors associated with bone loss in a group of postmenopausal (PM) women. Nutritional intake, inflammatory markers and body composition (weight, body mass index, fat/lean mass) were analysed for associations with bone mineral density (BMD).

DESIGN

A cross sectional study examining correlations between BMD (Duel-energy X ray absorptiometry; (DXA) and dietary intake (3-day diaries), body composition and plasma bone and inflammatory markers: C-terminal telopeptide of type I collagen (CTX) and procollagen type I N propeptide (P1NP), C- reactive protein (CRP), interleukin 6 and 10 (IL-6, IL-10), tumour necrosis factor (TNF) and osteoprotegerin (OPG).

SETTING

Community dwelling women from the Auckland, Hawke's Bay and Manawatu regions in New Zealand.

PARTICIPANTS

142 healthy, PM women aged 50-70 years.

RESULTS

OPG (per kilogram fat mass) was increased in women with osteoporosis (p<0.001) compared to groups classified with normal BMD and osteopenia. Protein, vitamin B12, zinc, potassium and dairy intake were all positively correlated with higher BMD while dairy and potassium intakes also inversely correlated with CTX. Body composition (weight, BMI and fat/lean mass) had strong positive associations with BMD. Multiple regression analysis showed body weight, potassium and dairy intake were predictors of increased BMD in PM women and explained 39% (r2=0.39, p< 0.003) of variance.

CONCLUSION

BMD was negatively correlated with OPG and positively with weight, dairy and potassium intake. This study highlights the importance of maintaining adequate body weight and emphasising dairy and potassium predominantly sourced from fruit/vegetables to reduce bone loss at midlife.

Midlife women, bone health, vegetables, herbs and fruit study. The Scarborough Fair study protocol

Background

Bone loss is accelerated in middle aged women but increased fruit/vegetable intake positively affects bone health by provision of micronutrients essential for bone formation, buffer precursors which reduce acid load and phytochemicals affecting inflammation and oxidative stress. Animal studies demonstrated bone resorption inhibiting properties of specific vegetables, fruit and herbs a decade ago.

Objective: To increase fruit/vegetable intake in post menopausal women to 9 servings/day using a food specific approach to significantly reduce dietary acid load and include specific vegetables, fruit and herbs with bone resorbing inhibiting properties to assess effect on bone turnover, metabolic and inflammatory markers.

Methods/Design

The Scarborough Fair Study is a randomised active comparator controlled multi centre trial. It aimed to increase fruit and vegetable intake in 100 post menopausal women from ≤ 5 servings/day to ≥ 9 servings/day for 3 months. The women in the dietary intervention were randomly assigned to one of the two arms of the study. Both groups consumed ≥ 9 servings/day of fruit/vegetables and selected herbs but the diet of each group emphasised different fruit/vegetables/herbs with one group (B) selecting from a range of vegetables, fruit and culinary herbs with bone resorbing inhibiting properties. 50 women formed a negative control group (Group C usual diet).

Primary outcome variables were plasma bone markers assessed at baseline, 6 weeks and 12 weeks. Secondary outcome variables were plasma inflammation and metabolic markers and urinary electrolytes (calcium, magnesium, potassium and sodium) assessed at baseline and 12 weeks. Dietary intake and urine pH change also were outcome variables. The dietary change was calculated with 3 day diet diaries and a 24 hour recall. Intervention participants kept a twice weekly record of fruit, vegetable and herb intake and urine pH.

Discussion

This study will provide information on midlife women’s bone health and how a dietary intervention increasing fruit and vegetable/herb intake affects bone, inflammatory and metabolic markers and urinary electrolyte excretion. It assesses changes in nutrient intake, estimated dietary acid load and sodium: potassium ratios. The study also explores whether specific fruit/vegetables and herbs with bone resorbing properties has an effect on bone markers.

Trial registration

ACTRN 12611000763943

The interaction between dietary protein and bone health

The role of dietary protein in bone health has been controversial. On the one hand, a plentiful supply of dietary amino acids has been considered important to support bone remodeling while on the other hand there have been concerns that the dietary acid load associated with protein consumption promotes hypercalciuria and loss of bone calcium stores. This article reviews the effect of dietary protein on bone mass and bone density, and the effect on markers of bone resorption and formation and also on fracture risk, looking at both cross-sectional and longitudinal studies and examining both meat and vegetable protein including soy and milk basic protein. The results are not entirely consistent and suggest that the interaction between dietary protein and other components in a mixed diet, such as calcium intake and vegetables and fruit to neutralize acid, are important and may determine whether high-protein diets are beneficial to bone health. Overall the results suggest that dietary protein has a modest beneficial effect on bone markers and bone density. This effect has yet to be consistently linked to reduced fracture risk, probably because of the role of other etiological factors such as the risk of falls. There is not enough evidence currently to suggest that animal protein is superior or inferior to vegetable protein, or that milk or soy protein, respectively, is more favorable than other protein sources.

Nutritional factors that influence change in bone density and stress fracture risk among young female cross-country runners

OBJECTIVE

To identify nutrients, foods, and dietary patterns associated with stress fracture risk and changes in bone density among young female distance runners.

DESIGN AND SETTING

Two-year, prospective cohort study. Observational data were collected in the course of a multicenter randomized trial of the effect of oral contraceptives on bone health.

PARTICIPANTS

One hundred and twenty-five female competitive distance runners ages 18-26 years.

ASSESSMENT OF RISK FACTORS

Dietary variables were assessed with a food frequency questionnaire.

MAIN OUTCOME MEASUREMENTS

Bone mineral density and content (BMD/BMC) of the spine, hip, and total body were measured annually by dual x-ray absorptiometry (DEXA). Stress fractures were recorded on monthly calendars, and had to be confirmed by radiograph, bone scan, or magnetic resonance imaging.

RESULTS

Seventeen participants had at least one stress fracture during follow-up. Higher intakes of calcium, skim milk, and dairy products were associated with lower rates of stress fracture. Each additional cup of skim milk consumed per day was associated with a 62% reduction in stress fracture incidence (P < .05); and a dietary pattern of high dairy and low fat intake was associated with a 68% reduction (P < .05). Higher intakes of skim milk, dairy foods, calcium, animal protein, and potassium were associated with significant (P < .05) gains in whole-body BMD and BMC. Higher intakes of calcium, vitamin D, skim milk, dairy foods, potassium, and a dietary pattern of high dairy and low fat were associated with significant gains in hip BMD.

CONCLUSIONS

In young female runners, low-fat dairy products and the major nutrients in milk (calcium, vitamin D, and protein) were associated with greater bone gains and a lower stress fracture rate. Potassium intake was also associated with greater gains in hip and whole-body BMD.

Proteins, dietary acid load, and calcium and risk of postmenopausal fractures in the E3N French women prospective study

Excess dietary proteins and "acid ash" diets have been suspected to increase the risk of osteoporosis, but experimental and epidemiological evidence is mixed. We aimed to determine whether the association between protein intake and the overall acid-base equilibrium of the diet (as renal net acid excretion [RNAE] estimate) and fracture risk vary according to calcium intake. During an average of 8.37 +/- 1.73 yr of follow-up, 2408 women reported a fracture (excluding high-impact trauma) among 36,217 postmenopausal women from the E3N prospective study. We used Cox regression models to study the interaction between calcium and, respectively, proteins and RNAE, from the 1993 dietary questionnaire for fracture risk determination, adjusting for potential confounders. There was no overall association between fracture risk and total protein or RNAE. However, in the lowest quartile of calcium (<400 mg/1000 kcal), high protein intake was associated with a significant increased fracture risk (RR = 1.51 for highest versus lowest quartile; 95% CI, 1.17-1.94). An increasing fracture risk with increasing animal protein intake was also observed (trend, p < 0.0001). A similar pattern of interaction for fracture risk was observed between RNAE and calcium. In this Western population of postmenopausal women with normal to high protein intake and fairly high calcium intake, there was no overall association between total protein or RNAE and fracture risk. However, there was some evidence that high protein-high acid ash diets were associated with an increased risk of fracture when calcium intake was low (<400 mg/1000 kcal).

Symposium on ‘Performance, exercise and health’ Practical aspects of nutrition in performance

The importance of nutrition in sport has been recognised since the ancient Olympians, and its role in improving both health and sports performance has widespread acceptance. However, in sporting circles nutritional knowledge, beliefs and practices are extremely varied. Within any sporting organisation the sports dietitian or nutritionist must be able to work with athletes, their family, coaches and other support staff to develop and monitor realistic and practical strategies that work best for each performer, contributing to a positive and sustained outcome on performance. The present review examines the practical application of current key issues in performance nutrition, highlighting the advantages of early intervention in youth development and comprehensive and integrated nutrition services.

Bone mass density, subsequent risk of colon cancer and survival in postmenopausal women

OBJECTIVES

To test the hypothesis that high bone mass density (BMD), a potential marker for cumulative exposure to endogenous estrogen, calcium and vitamin D intake, is associated with a lower risk of colon cancer, and that women with a lower BMD are likely to develop a more aggressive form of colon cancer, as defined by mortality.

STUDY DESIGN AND SETTING

BMD was measured in three different sites (Ward's triangle, trochanter, femoral neck) in 1,471 women 60 years of age. All incident cases of colon cancers were identified through record-linkage of cancer registry. The women were followed for a mean of 9.5 years.

RESULTS

Overall 31 cases of colon cancer were observed among 28.6 expected (standardized incidence ratio (SIR) = 1.09, 95% confidence interval: 0.79-1.25). The SIR decreased with increasing BMD showing a significantly decreasing risk of 20% for women who were at the higher BMD comparatively to women who were at the lower BMD in all the skeletal sites. The 10-year survival rates showed that survival was increasing with increased BMD, but not significantly.

CONCLUSION

The findings suggest that postmenopausal women with lower BMD have an increased risk of colon cancer. The biological mechanisms linking bone mass to colon cancer risk are not clear.

Clinical and radiographic improvement of rickets in Bangladeshi children as a result of nutritional advice

BACKGROUND

Calcium-deficiency rickets is common in south-east Bangladesh and responds to calcium supplementation.

AIM

To evaluate the healing effect on active rickets of a five-component nutritional advice programme aimed at doubling dietary calcium intakes.

METHODS

Forty-nine children aged <10 years with mild lower limb deformities and active rickets were followed over a period of 12 months. All were provided with a five-component nutritional advice programme advocating (i) the routine addition of 1 g limestone/kg rice, (ii) consuming small fish (including bones) instead of large ones, and (iii) daily consumption of 5 g ground sesame seeds, (iv) 100 g leafy vegetables and, if possible, (v) 100 ml of milk.

RESULTS

Radiographic scores improved in 90% of children. The response was positively associated with age (r=0.34, n=48, p=0.01) and severity of radiographic score at baseline (r=0.85, n=49, p<0.0001).

CONCLUSIONS

Despite the lack of a statistically significant association between radiographic improvement and compliance with nutritional advice, in mild calcium-deficiency active rickets, nutritional advice may be a cost-effective treatment and possibly a valuable long-term solution to the problem.

Intake of fruit and vegetables: implications for bone health

These famous words by Mencken in the early 20th century about the meaning of life and death, may also apply to the struggle of the healthy skeleton against the deleterious effects of retained acid!’ ( Kraut & Coburn, 1994). The health-related benefit of a high consumption of fruit and vegetables and the influence of this food group on a variety of diseases has been gaining increasing prominence in the literature over a number of years. Of considerable interest to the osteoporosis field is the role that bone plays in acid–base balance. Natural, pathological and experimental states of acid loading and acidosis have been associated with hypercalciuria and negative Ca balance, and more recently the detrimental effects of ‘acid’ from the diet on bone mineral have been demonstrated. Suprisingly, consideration of the skeleton as a source of ‘buffer’ contributing to both the preservation of the body's pH and defence of the system against acid–base disorders has been ongoing for over three decades. However, it is only more recently that the possibility of a positive link between a high consumption of fruit and vegetables and indices of bone health has been more fully explored. A number of population-based studies published in the last decade have demonstrated a beneficial effect of fruit and vegetable and K intake on axial and peripheral bone mass and bone metabolism in men and women across the age-ranges. Further support for a positive link between fruit and vegetable intake and bone health can be found in the results of the Dietary Approaches to Stopping Hypertension (DASH) and DASH-Sodium intervention trials. There is now an urgent requirement for the implementation of: (1) fruit and vegetable and alkali administration–bone health intervention trials, including fracture risk as an end point; (2) reanalysis of existing dietary–bone mass and metabolism datasets to look specifically at the impact of dietary ‘acidity’ on the skeleton.

Fast food consumption of U.S. adults: impact on energy and nutrient intakes and overweight status

OBJECTIVE

To compare the diet quality and overweight status of free-living adults, ages 20 years and older, grouped based on their fast food intake status.

METHODS

USDA's 1994 to 1996 Continuing Survey of Food Intakes by Individuals (CSFII 1994-1996) data was used. Three separate analyses were conducted: (1) effect of fast food on diet quality of males and females based on day-one data, (2) comparison of dietary and overweight status of adults who ate fast food on one- two- or none of survey days and (3) within-person analysis comparing energy and macronutrient intakes of adults who ate fast food on one of the two survey days. SUDAAN software package was used in pair-wise mean comparisons and regression analyses (alpha = 0.05).

RESULTS

At least one in four adults reported eating fast food. The diet of males and females who consumed fast food was high in energy and energy density. Fast food provided more than one-third of the day's energy, total fat and saturated fat; and was high in energy density. Negligible amounts of milk and fruits, but substantially large amounts of non-diet carbonated soft drinks were reported consumed at fast food places. After controlling for age, gender, socio-economic and demographic factors, energy and energy density increased and micronutrient density decreased with frequency of fast food consumption. Adults who reported eating fast food on at least one survey day had higher mean body mass index values than those who did not eat fast food on both survey days. A small, but significant, positive association was seen between fast food consumption and overweight status. Within-person comparisons showed that energy intakes were higher on a fast food day than on a non-fast food day.

CONCLUSION

Fast food consumption was associated with a diet high in energy and energy density and low in essential micronutrient density. Frequent fast food consumption may contribute to weight gain.

Lower estimates of net endogenous non-carbonic acid production are positively associated with indexes of bone health in premenopausal and perimenopausal women

BACKGROUND

The link between acid-base homeostasis and skeletal integrity has gained increasing prominence in the literature. Estimation of the net rate of endogenous non-carbonic acid production (NEAP) from dietary protein and potassium content enables exploration of the effects of dietary acidity or alkalinity on bone.

OBJECTIVE

The study aimed to ascertain whether lower dietary acidity (lower dietary protein intake but higher potassium intake-ie, low estimate of NEAP) was associated with greater axial and peripheral bone mass and less bone turnover, independent of key confounding factors.

DESIGN

Baseline (cross-sectional) results of a population-based study were examined further. The database includes spine and hip bone mineral density (BMD) in 1056 premenopausal or perimenopausal women aged 45-54 y and forearm bone mass and the urinary markers of bone resorption in 62 women. A validated food-frequency questionnaire was used to measure dietary intakes.

RESULTS

Lower estimates of energy-adjusted NEAP were correlated with greater spine and hip BMD and greater forearm bone mass (P < 0.02 to P < 0.05). Hip and forearm bone mass decreased significantly across increasing quartiles of energy-adjusted NEAP (P < 0.02 to P < 0.03), and trends at the spine were similar (P < 0.09). Differences remained significant after adjustment for age, weight, height, and menstrual status. Lower estimates of energy-adjusted NEAP were also correlated with lower excretion of deoxypyridinoline and were significant predictors of spine and forearm bone mass.

CONCLUSIONS

These novel findings provide evidence of a positive link between a ratio of lower protein to higher potassium dietary intake (ie, less dietary acid) and skeletal integrity.

An adaptive metabolic demand model for protein and amino acid requirements

The shortcomings of the metabolic implications of the current protein requirements model are reviewed, and an alternative model, validated with [1-(13)C]leucine balance results in human adults, is presented and evaluated in the context of defining protein requirements. The model identifies metabolic demands for amino acids as comprising a small fixed component and a variable adaptive component that is relatively insensitive to acute food or protein intake, but which changes slowly with a sustained change in intake, enabling N equilibrium to be achieved. The model accounts for the apparent low efficiency of utilisation of animal proteins in N balance studies and enables more realistic efficiency values to be measured within an experimental framework that takes account of the adaptive metabolic demand. However, the complex relationship between the adaptive metabolic demand and habitual level and quality of protein intake prevents prediction of protein quality by amino acid scoring, which can markedly underestimate actual values. In contrast to the current model, for fully adapted individuals risk of deficiency (i.e. negative N balance after complete adaptation) will only start to increase when intakes fall below the range of the true minimum requirements, i.e. a value that is currently unknown, but likely to be between 0.40 and 0.50 g/kg per d at the lower end of the reported distribution of requirements. At intakes greater than this with additional metabolic demands varying directly with intake, deficiency is only likely as a short-term response to a change to a lower intake within the adaptive range. Thus, for adults satisfying energy needs on most mixed human diets, intakes will be within the adaptive range, and N equilibrium ceases to be a useful indicator of nutritional adequacy of protein. In the context of prescriptive dietary guidelines it may be expedient to retain current values until the benefits (and any risks) of protein intakes within the adaptive range can be quantified. However, from a diagnostic perspective, indicators other than N balance need to be identified, since maintenance of N balance can no longer be used as a surrogate of adequate protein-related health.