Peak bone mass
Bone is a dynamic living tissue which is constantly being renewed by two types of cells: osteoblasts (build up new bone) and osteoclasts (break down old bone). Osteoblasts make a protein mixture, osteoid, which mineralises to become bone. Osteoclasts are the cells that break down bone and are responsible for bone resorption.
Bone formation and bone loss takes place throughout life, although at different rates and at different times. Up to around 25 years of age bone formation exceeds bone breakdown, thus bone mass is able to increase. Peak bone mass (PBM) is the greatest amount of bone density an individual can attain. PBM accretion is accelerate during growth spurts in the very young and teenagers with 90% of PBM established by the age of 18 in girls and 20 in boys. Bone density continues to increase more gradually until our mid-20s. At this point the balance between bone loss and bone formation stabilises. As we age, more bone is lost than formed and this is accelerated in women during the first six years of the menopause due to reduction in oestrogen levels.
Optimising PBM during the early years is of utmost importance to reduce osteoporosis and related fractures in older age. Once PBM is reached, maintaining accrued PBM in our 20’s and reducing the rate of bone loss in older age is also important.
To ensure a lifetime of healthy bones the World Health Organization (WHO) recommends that it is important to achieve the highest possible bone mass during the time of growth, to maintain bone health in early adulthood and to reduce the rate of bone loss in later life.
Nutrients important for bone health
As well as physical activity, adequate intakes of specific nutrients are key for optimal bone health.
The following nutrients in particular, as part of a healthy diet and lifestyle, are involved bone health:
- Vitamin D
- Vitamin K
- Vitamin C
The EFSA, after extensively reviewing the scientific literature, approved the health claim “contributes to the maintenance of normal bones” to be carried on food and drinks containing any of the above nutrients in significant quantities.
Plant-based eating and bone health
Plant-based eating can support normal bone growth and development throughout life, provided a wide variety of plant foods are consumed, and adequate intakes of protein, calcium, magnesium and vitamin C and vitamin D status are maintained.
Evidence from observational studies indicates those who follow plant-based eating patterns have a healthy bone mass, with no difference between omnivore and vegetarian populations.
Bone mineral density and urinarymeasures by diet group (omnivorous, OMN: lacto-ovo vegetarian, LOV; vegan, VEGAN)
|OMN (n = 27)||LOV (n = 27)||VEGAN (n = 28)||p|
|Bone mineral density, g/cm³||1.18 ± 0.11||1.12 ± 0.10||1.13 ± 0.11||0.384|
Strict vegans should pay attention to preserve protein and calcium intake, particularly during adolescence and young adulthood when peak bone mass is attained. There are a wide variety of plant-based protein sources, including peas, beans, lentils, nuts, soya dairy alternatives, tofu and soya mince, that can be consumed to ensure protein intakes.
Plant-based foods and bone health
Protein is a fundamental component of the bone matrix. Protein intakes whether from plant or animal sources are consumed in plentiful amounts across different population groups. Studies comparing intakes of omnivores, vegetarians and vegans have consistently demonstrated protein intakes across all groups to exceed recommendations. Additionally, the concept of ‘high biological’ and ‘low biological’ value or ‘complete’ and ‘incomplete’ proteins should be used with care as these terms can be very misleading especially when all plants do contain all essential amino acids, be it some at lower levels than the thresholds set for human needs.
The FAO approved Protein Digestibility Corrected Amino Acid Score (PDCAAS) and the Digestible Indispensable Amino Acid Score (DIAAS) measures the ability of a single food source of protein to provide all human essential amino acid needs, taking into account the amino acid quantity and digestibility. Unfortunately, what these scores do not reflect is the ability of a whole diet to meet essential amino acid needs over the course of a day, which is the deciding factor with regard to nitrogen balance in humans.
It has been repeatedly demonstrated that it is the overall intake of amino acids and meeting energy requirements over the course of a day that determines the ability of a diet to meet essential amino acid needs. Therefore, diets based solely on plants, which meet the daily energy requirements of an individual, will also meet all essential amino acid needs.
Calcium is now ubiquitous in the UK diet and cereal products such as bread are a significant contributor along with dairy. Other plant-sources of protein include tofu, beans and pulses as well as some nuts, green leafy vegetables (especially Kale and Pak-Choi) sesame seeds and tahini. Fortified soya-based alternatives to milk and yogurts are a source of high quality protein, calcium and vitamin D and many other plant-based drinks are also enriched with calcium and vitamin D. The bioavailability of calcium from fortified plant-based drinks and alternatives to yogurt has been proven to be comparable to that of dairy. Additionally, the calcium bioavailability of dark green vegetables such as Kale and Pak Choi have been shown to be significantly higher than dairy calcium.
One UK population group at risk of inadequate calcium intakes is teenager girls whose calcium intakes remain woefully low. This is a critical time of PBM attainment and ensuring this group meets its calcium needs will go a long way to help with bone health in older age.
Soya alternatives to drinks are fortified with calcium to a comparable level and bioavailability as that found in dairy. Additionally, many plant-based drinks and alternatives to yogurts are also fortified with vitamin D thus providing further bone health support.
Alpro non-organic plant-based drinks and alternatives to yogurt are enriched with calcium at 120 mg / 100 ml. The addition of gellan gum to our products avoids sedimentation of calcium in the pack and keeps all calcium in suspension.
Vitamin D food sources are few. Good sources include fortified plant-based drinks and alternatives to yogurts, a handful of fortified breakfast cereals and oil rich fish with some vitamin D also present in red meat and eggs. Most of our vitamin D is obtained from exposure to sunlight during the months of April to September when the sun’s rays are strong enough and at the right latitude to produce vitamin D. Therefore, the government recommends that during the winter months 10mcg vitamin D supplements should be taken by all. For some population groups including the under 5’s, elderly, dark skinned individuals and those who cover up most of their skin or keep out of the sun, a daily 10mcg vitamin D supplement is recommended throughout the year.
Alpro plant-based drinks and alternatives to yogurt are enriched with vitamin D, which is entirely plant-based. As vitamin D is helps to optimise absorption of calcium at gut level, plant-based products fortified with both calcium and vitamin D should be chosen.
Magnesium is found in many plant foods including green leafy vegetables like kale (which is also high in calcium), nuts and seeds, legumes, a variety of other brassica vegetables such as broccoli, cabbage and Brussels sprouts.
Vitamin K plays a key role in bone health and although it is found in some plant foods the majority is produced by our gut bacteria.
Vitamin C is found in citrus fruit, salad vegetables and berries.
Key contributors to dietary zinc in the UK diet are meat, poultry and eggs. However, zinc is also found in plant foods such as beans, peas, nuts, seeds and tofu.
Manganese is predominantly found in plant foods such as pineapples, nuts, oats and wholegrains.
Overall plant-based eating can provide all the essential bone health nutrients. Other essential lifestyle factors to consider for bone health include being more physically active (especially weight-bearing activity), avoid smoking, keep to a healthy body weight and moderate alcohol intake.
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