Fruit-vegetables and bone health
Without proper nutrition,
bones can become weak and brittle and joints can become damaged.
health related benefit of a high consumption of fruit and vegetables on a
variety of disease has been gaining increasing prominence in the literature over
a number of years. A number of observational experimental clinical and
intervention studies over the past decade have suggested a positive link between
fruit and vegetable consumption and the skeleton (or bones). The skeleton itself
has been referred to as "a giant ion exchange column loaded with an alkali
buffer," as 80% of body carbonate, 80% of body citrate, and 35% of body sodium
are contained in solution within the hydration shell of bone and are released in
response to metabolic acid.
A variety of population based studies published in the later part of the 1900s
and more recently between 2001 and 2003 have demonstrated a beneficial effect of
fruit and vegetable potassium intake on indices of bone health in young boys and
girls, premenopausal women, perimenopausal women,
postmenopausal women and elderly men and women.
Calcium can be found in foods
such as low-fat milk and yogurt, dark green, leafy vegetables such as kale and
broccoli, carrots, yams and fruits such as oranges.
- base homeostasis is critical to health and it is well documented that
extracellular fluid pH remains between 7.35 and 7.45. A major requirements
therefore of our metabolic system is to ensure that hydrogen ion concentrations
are maintained between 0.035 and 0.045 m Eq/L. Acid-forming foods (protein
and carbohydrates) drain calcium from the
bones; alkalizing foods (fruits, vegetables, seaweeds) neutralize the acids and
prevent calcium drain.
Major risk factors for
Advanced age, alcohol consumption, smoking, lack of
exercise, thinness, or being
underweight, use of pharmacological drugs, diet high
in protein, flour, and sweets, diet lacking vegetables,
high consumption of nightshade vegetables (potatoes,
tomatoes, peppers, eggplant).
Effect of dietary acidity:
On a daily basis, humans eat substances that both generate and consume
protons and, as a net result adult humans on a normal western diet generate
approximately 1 mEq per kg body weight of acid per day. Of course, the more
acid precursors a diet contains, the greater the degree of systemic acidity.
We know that as humans becomes older their overall renal function declines
which include their ability to excrete acid. Hence with increasing age
humans become slightly but significantly more acidic, leading to negative
calcium balance. Furthermore, osteoclasts and osteoblasts appear to respond
independently to small changes in pH in the culture media in which they are
growing. There is evidence that a small drop in pH close to the physiologic
range, causes a tremendous burst in bone resorption.
Role of potassium carbonate:
From a clinical point of view the study by sebastian and colleagues in
1994, which demonstrated that potassium bicarbonate administration resulted
in a decrease in urinary calcium and phosphorus, with overall calcium
balance becoming less negative or more positive is a very important study in
the investigation as to whether alkali is important for bone health. Changes
were also seen in markers of bone metabolism with a reduction in urinary
excretion of hydroxyproline (bone resorption) and an increased excretion of
serum osteocalcin (bone formation). Long-term studies looking at alkali
administration on indices of bone health throughout the lifecycle are now
The DASH Diet:
Further support for a positive link between fruit and vegetable intake
and bone health can be found in the
results of the DASH (Dietary Approaches to Stopping
Hypertension) and DASH sodium intervention trials. DASH diets rich in
fruit and vegetables were associated with a significant fall in blood
pressure compared with baseline measurements. However of particular interest
to the bone field were findings that increasing fruit and vegetable intake
from a 3.6 to 9.5 daily servings decreased the urinary calcium excretion
from 157 mm/d to 110 mg/d.
In summing up the evidence currently available, there is a positive link between
alkali administration and markers of bone health. Research is now required to
determine the long term clinical impact of alkalinity on bone health and
fracture risk as well as clarification of the exact mechanisms involved with
respect to this diet on skeletal protection.
Foods for improving bone health:
foods provide the major, readily absorbed sources of calcium. Women aged 40
and over should consume 3-4 serves of low fat dairy food daily. Other,
non-dairy sources of calcium include fortified breakfast cereals, canned
fish with edible bones, some nuts, seeds and green vegetables.
If calcium supplements are required, the best absorption rate is from a
dose of 500-600mg of calcium once or twice daily.
Avoid salty foods and adding salt to meals and during