Supporting bone health through the winter months; the role of physical activity and nutrition – conor raleigh

The winter months present a number of potential barriers and risks to bone health across the population and with World Osteoporosis Day occurring this month it is important to consider what we can do improve and protect our bone health.

Physical activity

Mechanical loading is considered the most potent stimulator of bone metabolism therefore physical activity has an extremely important part to play. Seasonal variations in levels of physical activity are well characterized and it is know that levels of physical activity decrease during the winter and fall months. This is possibly due to more inclement weather and less daylight hours in the northern hemisphere. However, a large population based study has shown that exercise for as little as 30 min per day has a positive influence on bone. The pattern and type of physical activity should also be considered. High impact, multidirectional, weight bearing movements (such as circuit training) are favoured over exercise that induces minimal load. These types of movements have a direct effect by positively stimulating bone metabolism, but also an indirect effect due to increases in muscle mass surrounding the bone which can then potentially magnify the gravitational load and apply muscle tension to the bone.

Vitamin D

The most important nutritional consideration for bone health during the winter months is Vitamin D. Vitamin D has a significant role in calcium metabolism and it is naturally synthesized in the lower layers of the skin epidermis in a chemical reaction that is dependent on exposure to UVB sunlight radiation. Reduced exposure to sunlight during the winter months means that the natural production of Vitamin D is reduced and it is highly recommended to supplement during this period. Vitamin D can be obtained from fortified food products such as milk and cereals or as a stand-alone supplement. The recommended daily intake of Vitamin D is 600 IU for most individuals but is slightly higher for those aged 70 and over at 800 IU . It should be noted that many supplements can contain up to 5000 IU of Vitamin D and hyper dosing should be avoided.

Other nutritional considerations

– 98 % of calcium in the body is stored in bone and it is important to protect this reserve with adequate dietary calcium to maintain good bone health. The recommended intake of Calcium again varies with age but most should be trying to consume 1000 mg per day. Dairy such as milk, yogurt and cheese are an excellent source of dietary calcium and 200ml of milk contains roughly 25% of the recommended intake – If you are exercising quite regularly or in a physically demanding job it is important to ensure that you are consuming enough energy to support this. Reduced energy availability (i.e. the energy available to the body after the energy used during exercise has been considered) is well known to have a negative impact on bone metabolism and if maintained for an extended period can lead to compromised bone health.