Impact of phytochemicals on maintaining bone and joint health

Potential Role of Lycopene in the Prevention of Postmenopausal Bone Loss: Evidence from Molecular to Clinical Studies

Osteoporosis is a metabolic bone disease characterized by reduced bone mineral density, which affects the quality of life of the aging population. Furthermore, disruption of bone microarchitecture and the alteration of non-collagenous protein in bones lead to higher fracture risk. This is most common in postmenopausal women. Certain medications are being used for the treatment of osteoporosis; however, these may be accompanied by undesirable side effects. Phytochemicals from fruits and vegetables are a source of micronutrients for the maintenance of bone health. Among them, lycopene has recently been shown to have a potential protective effect against bone loss. Lycopene is a lipid-soluble carotenoid that exists in both all-trans and cis-configurations in nature. Tomato and tomato products are rich sources of lycopene. Several human epidemiological studies, supplemented by in vivo and in vitro studies, have shown decreased bone loss following the consumption of lycopene/tomato. However, there are still limited studies that have evaluated the effect of lycopene on the prevention of bone loss in postmenopausal women. Therefore, the aim of this review is to summarize the relevant literature on the potential impact of lycopene on postmenopausal bone loss with molecular and clinical evidence, including an overview of bone biology and the pathophysiology of osteoporosis.

Lifestyle and osteoporosis

Osteoporosis is associated with a number of lifestyle factors, including nutritional factors such as intake of calcium, protein, dairy food, fruits and vegetables and vitamin D status, and behavioural factors such as physical activity, smoking and alcohol consumption. Ensuring adequate calcium intake and vitamin D status and having regular weight-bearing physical activity throughout life are important for bone health and the prevention of osteoporosis and related fractures. Studies have shown that smoking and excessive alcohol intake have adverse effects on bone health and increase the risk of fracture. There is evidence suggesting that adequate protein intake and higher intake of fruits and vegetables are beneficial to bone health.

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

Fruit and vegetable intake and bone health in women aged 45 years and over: a systematic review

High fruit and vegetable intake may be associated with improved bone status among women aged ≥ 45 years. This is the first systematic review that specifically assessed this association and identified research gaps. The benefits of fruit and vegetables (F&V) on bone health remain unclear. Further studies are needed.

INTRODUCTION

F&V have several components that are beneficial to bones. Some studies report that high F&V intake is associated with improved bone status in middle aged and aged women; however, findings are inconsistent. The objective was to systematically review observational and interventional studies that investigated the effects of F&V intake on incidence of osteoporotic fractures, bone mineral density (BMD), and bone turnover markers (BTM) in women aged ≥ 45 years and to identify potential research gaps.

METHODS

Electronic databases were searched, and peer-reviewed manuscripts published in English, with F&V intake as a main dietary exposure, were included. Data selection, extraction, and evaluation of risk of bias were performed independently by two reviewers.

RESULTS

Eight studies were included. One cohort study reported cross-sectional as well as longitudinal data. There was significant between-study heterogeneity in design, definition, and amount of F&V intake, outcomes, analyses, and reporting of results. Two studies had low, two had moderate, and four had high risk of bias. Among reports with low or moderate risk of bias, two cross-sectional analyses reported positive associations between F&V intake and BMD of the forearm, lumbar spine, or total hip, whereas one randomized controlled trial and two prospective cohort analyses reported no effects. One trial reported no associations between F&V and BTM.

CONCLUSIONS

Based on limited evidence, the benefits of F&V on bone health remain unclear for women aged ≥ 45 years. Further studies with low risk of bias are needed.