Nutrition for healthy bones

Dr Linia Patel explores the lifestyle factors integral to helping you and your clients protect their bones at the different life stages.

I read a mind-boggling statistic the other day: “Every three seconds, there is an osteoporosis fracture in the world”¹. Worldwide, that makes fractures from osteoporosis more common than heart attacks, strokes and breast cancer combined! Osteoporosis is linked with weak bones and is dubbed the ‘silent thief’, as you don’t feel the damage while it proceeds. Many adults will not be aware they have porous bones until they happen to fall. Falls that result in a fracture to your bones impact on your quality of life massively and, if you’re elderly, your chance of dying shortly afterwards skyrockets¹. Strong and healthy bones are vital to good health and good nutrition is crucial to strong bones.

Bone physiology 101^1,2

About every 10 years, you end up with a completely new skeleton. This is because bones may look hard and static, yet they are living and dynamic tissues. They are constantly breaking down and remodelling themselves. Remodelling in simple terms means removing old bone and laying down new bone. If we are well nourished, then our bones remodel themselves optimally. If you are low on nutrients, the construction crew in your bones do the best they can with what they’ve got; however, as they don’t have the material, they need to cut some corners on the job and, as a result, the overall structure is weak and susceptible to breaking (i.e., fracture).

Physiologically, bones are not just walls of calcium either. Much of your bone structure is a matrix of minerals, with protein, connective tissues and a network of nerves and blood vessels, and the marrow at the centre. Bone density is a measure of the amount of calcium and other minerals found in your bones. Both osteopenia (low bone mass) and osteoporosis (brittle bones) are conditions characterised by low bone density. Worldwide, one in three women over the age of 50 will experience osteoporosis fractures, as will one in five men aged over 50.

How bones evolve over time^2,3

Our bone health evolves throughout our lives. To begin with, what our mothers eat while pregnant will affect our eventual bone mass as adults. In your childhood years, minerals are incorporated into your bones and your bones have the most rapid growth. This is why, if you break a bone when you are a child, you heal very quickly. By 18 or 19 years, we reach about 95% of our peak bone mass. We can continue to build some bone in our 20s; however, by the age of 30, all the bone deposits are complete. If not enough bone mass is created during this time, you will have an increased risk of developing fragile bones that can break easily. As part of the natural ageing process, both women and men begin to lose bone density and, in Western cultures, it is estimated that people lose about 0.5% of bone mass each year after the age of 40. Women from their forties typically lose bone mass at a drastic rate during menopause transition, when bone-protecting oestrogen levels drop. If you have chronic bone loss, that leads to low bone mineral density and a deterioration of bone.

A prior fracture is associated with an 86% increased risk of any fracture, so learning to eat for your bones is pivotal

Populations at risk of poor bone health^4,5,6

There are some groups that are at risk of having poor bone density. These include people who have cut out dairy in their diets, those who follow excessive and extreme diets that don’t provide enough total energy and post-menopausal women.

1. Chronic and extreme dieters: First and foremost, strong bones need enough energy coming in. Extreme diets and aggressive weight loss will increase your risk of getting in the red zone. The technical term for this is Relative Energy Syndrome (RED-S). Not getting enough energy sets off a negative hormonal cascade, which has an impact on bone mass. This is why disordered eating has a long-lasting negative influence on bone health. However, RED-S can happen at any age and bodyweight and still have a detrimental impact. For example, one study found that obese women who consumed only 925 calories per day for four months experienced a significant loss of bone density from their hip and upper thigh region regardless of whether they performed resistance exercise⁷. Personally, and anecdotally in the last decade, I have seen an increase in the referrals for fractures with my sports nutrition practice linked to RED-S. What is scary is that a prior fracture is associated with an 86% increased risk of any fracture, so learning to eat for your bones is pivotal⁸.
2. Dairy-free diets⁶: You can eat plenty of calcium but it is important to consider its bioavailability. There are nutrients called phytates and oxalates found in foods that bind up minerals and prevent us from extracting them. Phytates are found in grains, seeds and nuts and oxalates are found in spinach, sweet potatoes and rhubarb, for example. This means foods like spinach (which contain calcium) are not necessarily good sources of calcium. If you are vegan, for example, you need to be conscious of your calcium intake to ensure you consume enough that is bioavailable to you. Here is a list of foods and their related bioavailability.
3. Menopausal and post-menopausal women⁴: Around 10% of a woman’s bone mass is lost in the first five years of the menopause and this increases your risk of osteoporosis, a condition where your bones are more likely to break. After the menopause, women are more likely to be affected by osteoporosis. This is because oestrogen helps to keep your bones strong and healthy. Less oestrogen puts you at risk of developing osteoporosis. Muscles and bones are also intricately linked and lower testosterone and oestrogen levels also put women in the menopause transition at an increased risk of losing muscle mass.

 

Foods	Bioavailability of calcium (%)
Dairy products	95-97
Chinese cabbage	95
Tofu with calcium	80
Pak choi	43
Kale	30
Beans	10-25
Rhubarb	10
Sweet potato	10
Spinach	6

 

Good nutrition, good remodelling^4,6,9,10

Nutrition is vital for healthy bones. Good nutrition supports bone mineralisation and helps keep the whole skeletal complex healthy as well. From a nutrition point of view, these are the factors you need to get right.

Protein intake

Fifty percent of bone is made of protein, so it is important to get enough protein. Protein intake can also influence growth hormones and growth factors in the body, which indirectly affect bone health. Lack of protein also robs the muscle of strength, which increases the risk of falls. A large six-year observational study including over 140,000 post-menopausal women found that a higher protein intake was linked to a lower risk of forearm fractures and significantly higher bone density in the hip, spine and total body¹¹.

Calcium

Calcium is a major building block of the bone matrix. Bone contains about 99% of the body’s calcium. As bone is constantly being remodelled, it is important to consume enough calcium daily to protect bone structure and strength. That said, the calcium you consume cannot build a strong skeleton on its own. It needs to have the correct hormonal signals (such as enough energy and enough vitamin D), as well as mechanical signals (such as resistance exercise) to tell it where to go.

The recommended daily intake for calcium in the UK for adults aged 19-64 is 700mg. Adolescent boys and girls needs more (1,000mg and 800mg respectively), as do breastfeeding women (1,250mg). However, there are some things to keep in mind when it comes to calcium, which include bioavailability and absorption.

Top tips on calcium intake:

• It’s best to get calcium from food vs supplements.
• For maximum absorption of calcium from food, spread your calcium intake throughout the day.
• Avoid supplementing with more than 1,000mg of calcium daily.
• Excess supplemental calcium can actually be harmful.

Vitamin D

Vitamin D and calcium are like strawberries and cream. They are meant to go together. If your blood levels for vitamin D are under 30ng/ml (75nmol/L) your calcium absorption drops by 10-15%. This is why it is important to aim for optimal vitamin D levels. In the UK, current government vitamin D guidelines are that people take 10mg of vitamin D a day from autumn through winter and longer if you spend a lot of time indoors¹². Within my clinical practice, just to maintain healthy vitamin D levels in autumn and winter I recommend 1,000IU per day, which is 25mg.

Other vitamins and minerals

A host of other minerals are important in forming bone mineral. Vitamin K acts as a shuttle for calcium to get into the bone. Some evidence suggests that low vitamin K levels lead to low bone density and increased risk of fracture in the elderly. Vitamin K sources include leafy green vegetables such as kale, cabbage and spinach, as well as fermented cheeses and soybean products.

Zinc and magnesium are also both minerals involved in tissue renewal and mineralisation. Although deficiencies in both are rare, elderly people are at risk of deficiency of both these minerals due to a decreased absorption. Sources of magnesium include leafy green vegetables, legumes, nuts and seeds, and wholegrains. Zinc is found in lean red meat, poultry, wholegrain cereals, pulses and legumes.

Some new research suggests that high levels of the amino acid homocysteine may be linked to lower bone density and higher risk of hip fracture in the elderly. Vitamin B6 and B12, as well as folic acid, play a role in changing homocysteine into other amino acids for use by the body, so it is possible that they both play a preventative role in osteoporosis. Research is ongoing as to whether supplementation with these B vitamins may reduce fracture risk.

Vegetables and fruit

A diet that is rich in colourful vegetables and fruit has been linked to increased bone density too. One of the reasons is that these foods are rich sources of vitamin C, which stimulate the production of bone-forming cells. The vitamin C, alongside other phytonutrients (particularly flavonoids), has antioxidant effects that may protect the bone cells from damage. Some flavonoids also found in beans, wholegrains, nuts and seeds may also influence bone cell signalling and prevent oxidation. All these links with bone health have been shown to be protective during childhood until old age.

Collagen

While there is not strong evidence yet, this is an interesting area of research to watch. Preliminary studies suggest that collagen supplements may help protect the bone by reducing collagen breakdown. Collagen is the main protein found in bones.

Lifestyle for bones

Strong bones need the right nutrition and the right mechanical stimulus, which is why it is important to perform weight-bearing and resistance-training exercises. Research has shown that regular weight-bearing exercise can help to increase bone formation during bone growth and protect bone health in older adults, including those with low bone density. Similarly, too much alcohol and smoking are other lifestyle factors that have a negative impact on bone health.

Weight-bearing exercise can help to increase bone formation during bone growth

Take-home messages

For strong, healthy bones, follow these tips:

1. Keep on top of your vitamin D levels.
2. Consume several calcium-rich foods each day. If you are plant-based, ensure you focus on including bioavailable calcium sources in your diet too.
3. If you consider using supplements for bone health, be sure to speak to a health professional to guide you. High dose supplementation will not help you and be harmful.
4. Maintain a healthy bodyweight. Being too heavy or too light can negatively influence bone mass. If you need to lose weight, do so in a moderate way. Avoid extreme and excessive diets.
5. Ensure that you consume lean protein at each meal daily.
6. Keep it colourful: pigment-rich vegetables and fruits deliver vitamins, minerals, phytonutrients and flavonoids – all of which are crucial for bone health.
7. Drink in moderation. Stay within recommended limits.
8. Load those bones. Ensure you incorporate weight-based movement in your exercise routine. Lift weights. Jump. Run. Walk. Carry things.

Like to find out more about nutrition for healthy bones and longevity? Read more on the FitPro blog.

References

1. Osteoporosis foundation:Epidemiology of osteoporosis and fragility fractures | International Osteoporosis Foundation
2. Clarke B. 2008. Normal bone anatomy and physiology. Clinic J Am Soc Nephrol. S131-S139
3. Curtis, E., et al., Epidemiology of fractures in the United Kingdom 1988-2012: Variation with age, sex, geography, ethnicity, and socioeconomic status. Bone, 2016. 87: p. 19-26.
4. Munoz-Garach A. 2020.Nutrient and dietary patterns related to osteoporosis.Rev Food Sci Nutr. Nutrients.3;12 (7),1986
5. Konstantia D et al. 2020. Relative energy deficiency in sports (RED-S): elucidation of endocrine changes affecting the health of male and females. Hormones. 81); 35-47
6. Cashman K. 2002. Calcium intake, calcium bioavailability and bone health. Br J Nutr. Suppl 2:S169-77
7. Palak C et al. 2014. Weight loss and bone mineral density in obese adults: a longitudinal analysis of the influence of very low energy diets. Am J Clin Nutr.9984):934-40
8. Kanis, J., et al., A meta-analysis of previous fracture and subsequent fracture risk. Bone, 2004. 35(2): p. 375-82
9. Palacios C. 2012. The role of nutrients in bone health, from A to Z. Open Orthop. 6: 143-149
10. Price C et al.2018. Essential Nutrients for Bone Health and a Review of their Availability in the Average North American Diet. Clin Diabetes Endocrinol. 4: 14
11. Beasley J et al. 2009. Biomarker-calibrated protein intake and bone health in the Women’s Health Initiative clinical trials and observational study. 16: 32-48
12. British Dietetic Association, Vitamin D: https://www.bda.uk.com/resource/vitamin-d.html