In October of last year I wrote about eating for bone health and mentioned the clear and positive associations between fruit and vegetable consumption and strong bones (1). The post concentrated mainly on the way these foods act to effect the pH balance within the body. Fruits and vegetables contain a huge array of vitamins, minerals and phytonutrients/flavonoids (chemically active plant compounds) that may also act to strengthen bone.
Last month a paper was published in the American Journal of Clinical Nutrition (2) which points toward the bone protective effects of carotenoids. Previous evidence suggests that carotenoids may be acting to prevent bone loss and also to stimulate bone cell growth. Carotenoids, found abundantly in fruit and vegetables, act as antioxidants in the body and it is this mechanism that may be protecting the bones from damage by naturally occurring unstable oxygen molecules in the body, known as free radicals. Antioxidants may help to ‘quench’ the destructive free radical molecules and therefore protect against damage. As nutrients, antioxidants are ingested in the diet and are then distributed via the blood into various parts of the body tissues, including the bones.
The researchers involved in this latest study (2) looked at the potential effects on bone mineral density of overall and individual intake of several carotenoid compounds, including alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, lutein and zeaxanthin. The study scientists tracked the bone mineral density in the hip and spine of 213 men and 390 women over the course of four years. They found that carotenoid intake was associated with some levels of protection against bone mineral density losses at the hip in men and at the spine in women. The results suggest that carotenoids, especially lycopene, may be protective against bone loss in older adults. Further studies are certainly needed but the evidence adds further weight to the mounting data which shows just how important fruits and vegetables are to the whole body, including our bones.
A diet rich in colourful fruits, vegetables will provide plentiful amounts of antioxidants. Carotenoids are a family of over 700 naturally occurring yellow, red, orange and dark green pigments found in vegetables and fruits. Good sources include carrots, sweet potatoes, tomatoes, squash, peppers, cantaloupe melons, nectarines, papaya, mango and dark green vegetables such as spinach, kale, watercress and asparagus. Introducing a good mix of these fruits and vegetables on a regular basis in the diet will help keep carotenoid levels in the body high.
Absorption of carotenoids from foods into the body is greatly affected by fat. Without a fat source carotenoids are not easily absorbed. Fat acts as a carrier for these nutrients to allow them passage from the gut into our blood and bodily cells. I am certainly not suggesting that you drown your vegetables or salads in gallons of oil, however, I am a firm believer in using small amounts of olive oil in dressings and cooking. Including some nuts, seeds or olives in salads may also be helpful in order to gain maximum absorption of these important nutrients.
If you are looking at carotenoid supplements, especially lycopene, look for those that contain an oil carrier, these will aid maximum absorption. Of course fruits and vegetables contain far more than just carotenoids and a supplement cannot be seen as a substitute for good dietary habits, but if you feel that you do not get a good variety of vegetables and fruits in your daily diet you may wish to consider a supplement to help make up for any short-fall.
It is particularly important that young people look after their bone health, a balanced diet as well as exercise is vital in this respect. Recently the National Osteoporosis Society (NOS) produced a press release and report regarding their findings that young people in the UK are endangering their health by not looking after their bones. Prevention is the key to osteoporosis which affects up to three million people in the UK.
The NOS found that (3) that less than a quarter of people knew they should start looking after their bones before the age of 30, despite the fact that bone strength actually peaks during our 20s. Younger people need to ‘bank’ plenty of bone by the age of 30 as bones tend not to regenerate as quickly after that.
• Almost half (49%) of young people (18-24 yrs) did not know there were any steps they could take to keep their bones healthy;
• More than half were unaware that exercise can help reduce the risk of osteoporosis;
• One in three did not know about the positive role diet can play.
Professor Roger Francis, Chair of the charity’s Medical Board, states(3):
“Our bones are living tissue, much like our skin. New bone replaces old throughout our lives. But the most crucial years are when we’re young as this is when the cells building new bone are most active. Until our mid 20s our bones are gaining density and strength. From our 30s onwards our bones gradually lose their density. The more we can build up our bones when we are young the better we can help to protect ourselves against osteoporosis and fragility fractures in later life.” (3)
Women are more at risk of developing osteoporosis since their bones are smaller and also more vulnerable to hormonal changes. Being underweight, and having a low BMI (body mass index) is also a big risk factor. Currently many girls and women are striving to reach a low bodyweight and achieve the size zero that is touted by so many celebrities. The report found that only 21% of people knew that being underweight was a significant risk factor for osteoporosis development (3).
Encouraging young people to eat fruit and vegetables, as well as foods rich in calcium, magnesium and other minerals is very important for bone strength and development. Please visit the National Osteoporosis Society website for more information about bone health. A very informative document about osteoporosis can be downloaded from the site and my post about eating for strong bones may also be of interest.
(1) New SA. 2003. Intake of fruit and vegetables:implications for bone health. Proc Nutr Soc. 62:889-899
(2) Sahni S et al. 2009. Inverse association of carotenoid intakes with 4-y change in bone mineral density in elderly men and women: the Framingham Osteoporosis Study. Am J Clin Nutr 89: 416-424
(3) NOS press release
Written by Ani Kowal
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