Sunday, September 9, 2012

Flavonoids Increase Bone Mineral Density

When people ask me what is the most important thing they can do for improving bone health, I think they're expecting me to suggest a certain form of calcium supplement. There is no doubt, supplementing with quality calcium, such as that found in OsteoSustain and OsteoMineralBoost, is important, but remembering to take a few tablets each day is easy. What's more difficult is to remember to eat five to eight servings of fruits and vegetables, every day. So my answer to their question tends to be "EAT YOUR FRUITS AND VEGETABLES!" When you have bone loss, you need to do EVERYTHING you can to improve your overall health, and a diet rich in fruits and vegetables is the perfect place to start.

Fruits and vegetables are rich in vitamins, minerals, and phytochemicals called antioxidants. Without antioxidants we would not be able to neutralize the ravaging effects of free radicals and limit the oxidative stress that leads to cellular breakdown and aging. There are a number of classes (as well as subclasses) of naturally occurring phytochemicals: vitamins, carotenoids, curcuminoids, lignans and flavonoids. By consuming a diet poor in phytochemicals, we become susceptible to disease. In this month's issue of the Journal of Bone and Mineral Research, Welch et al. (2012) investigated the effect of different flavonoids on human bone density. Flavonoids are found in the pigments that give fruits and vegetables their rich yellow, orange, red and blue colors. Due to their extreme complexity, and variability in biological efficacy and availability, flavonoids have been further categorized into subclasses. These subclasses are: "flavonols, flavones, flavanones, flavan-3-ols and their oligomeric and polymeric forms (i.e. procyanides), isoflavones, and anthocyanins and other polymeric flavonoids."

One of the most intensely studied subclasses of flavonoids to be assessed for their effects on bone are the isolated components of soy called isoflavones. Supplementing with high doses (90 mg/day) of isoflavones have been shown to reduce bone loss (Ma et al. 2008) but this improvement may only be seen with high supplemental intake. When dietary isoflavones are studied for their effect on bone (for example, Mulligan et al. 2007) there is often no detectable improvement. With concerns that the estrogen-like effects of supplemental isoflavones can vary between estrogen-boosting and estrogen-blocking, depending upon the age and health of an individual, I have tended not to recommend supplemental soy isoflavones (including ipriflavone) to my patients. Soy in the diet is OK (unless you have a sensitivity to it) but I'm just not sold on them for inclusion in supplements.

What has become apparent to me with phytochemicals is that their value increases when consumed in their natural state (compared to extracting them and consuming them as supplements). There are over 4,000 flavonoids, and their beneficial effects are most powerful, and additive, when taken together. This is why a diet high in fruits and vegetables is superior to supplementing with individual phytochemicals. The reason is the "additive effect" from consuming the "whole."

In addition to confirming that a higher intake of plant-based flavonoids is associated with higher bone mineral density (BMD), Welch et al. found anthocyanins (a flavonoid and polyphenol) to be particularly important to bone health. They concluded that "a higher intake of anthocyanins was associated with a 3.4% and 3.1% higher BMD at the spine and hip, respectively."

My take home messages to you are: 1) the additive effect of flavonoids makes the consumption of fruits and vegetables superior to supplementing with extracts, and 2) the higher the anthocyanin content, the better that fruit or vegetable is going to be for bone health. Dried plumes, by the way, are rich in the purple flavonoids, anthocyanins.

Welch et al. 2012. Habitual flavonoid intakes are positively associated with bone mineral density in women. Journal of Bone and Mineral Research 27(9):1872-1878.

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