Nutrition is a very dynamic science. I look back to the 90’s when everything in my household was “fat free” and thought I was eating right! Luckily, most of the population has turned away from the low fat frenzy where bagels and pasta were unlimited and realized that carbohydrates may be a target of dietary modification.
Two specific nutrients I get many questions on are calcium and vitamin D. Below you will find some thoughts on the utility of dairy products and sun exposure!
Myth: You must eat dairy products to get calcium and keep bones strong
Calcium is found in a wide variety of foods, including dairy products. The problem with dairy is that some people have sensitivities (can present as eczema, acne, IBS), it tends to be pro inflammatory/mucus producing (chronic sinus or respiratory issues) and many people do not have the enzymes (lactase) necessary to digest dairy. The belief that dairy prevents fractures and supports bone health has not been supported by research. The Harvard Nurses’ Health Study, followed more than 75,000 women for 12 years, showed no protective effect of increased milk consumption on fracture risk. In fact, increased intake of calcium from dairy products was associated with a higher fracture risk.
Calcium is a very important mineral, but choose your sources of calcium wisely. Try to get a variety of calcium containing foods in your daily diet:
Bone strength depends on more than just calcium. Vitamin D, magnesium and vitamin K are also important for bone health.
Myth: You only need vitamin D supplementation in the winter.
It is true that our vitamin D levels can dip in the winter, which may be a cause for seasonal depression. When the sun is out in the summer months, are you getting enough D on a daily basis? Individual requirements for vitamin D vary widely, making follow up blood testing important to see if optimal blood levels are being achieved. Target blood values are usually > 70 on standard blood panels.
The ability to make vitamin D from the sun is dependent on our geographic location. In areas north of 35-37 degrees latitude, little to no vitamin D is made November to February. For reference, Chicago is at 41 degrees north and Phoenix is at 33 degrees. Also, any sunscreen over SPF 8 will block the sun’s ability to make vitamin D. Caucasians need approximately 20 minutes per day between 10 and 2pm of direct sunlight, most of skin uncovered (think bikini or swim trunks!), to make their daily dose of vitamin D. Darker skinned individuals need a longer duration in the sun to allow for absorption, approximately 40 minutes or more. During sunbathing, the body can make up to 20,000 units in this 20 minute time period.
Food sources that are high in vitamin D are fortified; therefore sun exposure and supplementation are critical.
Vitamin D is best absorbed and utilized with vitamin K (both K1 and K2), so I usually recommend supplementation containing D and K. Look for cholecalciferol (D3) which is the active form of D that you make from the sun!