Please seek advice from your physician if you think you need a calcium and/or Vitamin D supplement. This post is a sharing my of personal experience and thought process to help stimulate thought in others - not as a prescription!
I recently went to my doctor and at the end of our visit, she reminded me to bump up my calcium intake to reduce risk of osteoporosis. I sat there for a moment and thought to myself, "What? I get plenty of calcium from my diet already." Then I thought about it - I'm not that young anymore. I'm 46 years old and I'm going through menopause now. And that's not even early menopause (that would be age 40 years or younger). So, I pulled out my Dietary Reference Intakes (DRIs): The Essential Guide to Nutrient Requirements and reminded myself of the age categories for nutrient requirements. Since the average age of menopause is about 51 years, it is no wonder that the nutrient requirements for calcium and iron both change with the 51 - 70 year age group. Calcium requirement goes up with the decrease in circulating levels of estrogen and iron requirement does down with cessation of monthly blood loss. Vitamin D requirement also increases, in part to support serum (blood) levels that maximize calcium absoprtion (as well as for other reasons).
Since I really dislike taking pills, I decided to review my current dietary intake of calcium and vitamin D to see how it compares to the Dietary Reference Intake's "Adequate Intake" for my new age group of 51 - 70 years: 1200 mg/day and 400 IU/day, respectively.
I pulled out and examined the nutrition labels of all my foods that are typically great sources of calcium: milk, yogurt, cheese, fortified soy milk, and fortified orange juice. Unfortunately, amounts of calcium and vitamin D are not listed on Nutrition Facts labels - instead, the infinitely annoying "%DV" (Daily Value) is listed. As a dietitian, I'm supposed to be thrilled with this educational tool, but instead, I find it just confuses people. If the link I gave you in the previous sentence is not helpful, try the list I found on the Mayo Clinic's website - they have a chart of the actual nutrient amounts associated with each Daily Value. FYI, the Daily Value for calcium is 1000 mg, 30% DV = 300 mg, 10%DV = 100 mg, etc. After reviewing my typical daily intake of calcium-rich foods (1 cup skim milk, 1 part-skim cheese stick, 1 cup fortified soy milk, 1/2 cup fortified orange juice, and 1 container of Dannon Activia), I calculate my average intake to be ~1125 mg/day - perfect if I wasn't in menopause. Although I am likely getting some calcium from my dark green leafy veggies and beans, these are also typically high-phytate and/or high-oxalate dietary sources of calcium with much lower bioavailability so I won't bend over backwards to calculate or estimate calcium intake from these sources. Fortified breads also have calcium (e.g. Sara Lee Heart Smart bread has 60mg/slice) but homemade breads have a lot less (e.g. closer to 15 mg/slice). I don't eat a lot of bread, so it's not a signficant source of calcium for me.
My goal is to bump up to 1200 mg of calcium per day. To do that , I'm simply going to include an extra 1/2 cup of skim milk or fortified soy milk each day so that I average 1275 mg calcium. I am not concerned about going over 1200 mg/day - the DRI's Upper Limit (total from food/beverages and supplements) for calcium is 2500 mg/day. I'm not concerned about weight gain with this added 40 - 50 calories/day since I tend to eat less at a meal (especially dessert) if I include milk or soymilk.
For those of you who don't like dairy or fortified soy or orange juice, you might want to ask your doctor about the need for a calcium supplement. I like this guide from the University of Arizona Cooperative Extension.
Reading food labels was only mildly helpful. VItamin D is sometimes on the label, but often it is not. The Daily Value for Vitamin D is 400 IU, so 30%DV = 120 IU (e.g. fortified soy milk), 25% DV = 100 IU (e.g. fortified skim milk). Note that some of best sources of Vitamin D are found in foods that don't have food labels: fatty marine fish (the kind also high in healthy omega-3 fats such as salmon, tuna, and sardines). Cod liver oil is probably the singlest highest source - 1 teaspoon provides 450 IU Vitamin D.
In addition to food, sunlight exposure allows conversion to the active form of Vitamin D in the skin. Although I live in Colorado (tons of sunny days), it is now cool weather so my limbs are covered when I go outside. Also, I always wear sunscreen on my face, so I'm not getting very much UVB radiation right now. So, during the cold seasons, I won't rely on the sun to meet my Vitamin D needs.
If you want more information on Vitamin D, the National Institutes of Health has a nifty Office of Dietary Supplements that provides useful information on all nutrients. Note that Vitamin D is in the news these days and there is a lot of controversy over how much people in different age groups should be getting. The complaint is that the "Adequate Intake" of 400 IU is too low, and that the "Upper Limit" (tolerable upper intake level) of 2000 IU is also set too low (see Heaney's abstract for just one example).
Given my typical daily intake, I average around 320 IU of Vitamin D. Should I take a supplement? Given that I won't take cod liver oil, and as much as I love salmon, I won't eat it (or fish in general) every day. So, yes, I will start taking a Vitamin D supplement during the winter months. I'll try Vitamin D3 (cholecalciferol) and see how I tolerate that since some research shows that it is more effective than Vitamin D2 at increasing serum levels of 25-hydroxyvitamin D. I'll find a supplement that allows me to take 1 small pill daily (I hate large pills - they make me gag). I'll aim for about 1000 IU daily intake during the winter months.
I hope that this has been useful for those of you going through menopause or are postmenopausal. For the men, note that the DRI's "Adequate Intake" for Vitamin D and calcium is the same as it is for postmenopausal women but your risk for osteoporosis is a bit lower than it is for women.
Best to you - Kathy