Vitamin D and Skin Pigmentation

I was recently asked “How much is Vitamin D production reduced by increased skin pigmentation?”

I’ve been searched for a while in hopes of finding a more accessible source, unfortunately I haven’t found a review of the evidence that is as thorough as the one in Dietary Reference Intakes for Calcium and Vitamin D (2011), starting on page 101 (…/dietary-reference-intakes-for-calcium-…), in the section “Effect of skin pigmentation on synthesis”. The short answer to the question seems to be that, in comparing individuals with the least pigmentation to individuals with the most pigmentation, there can up to twice as much production of Vitamin D in the individuals with the lightest pigmentation, but that there is not a linear relationship between skin tone and Vitamin D production, meaning that you cannot predict Vitamin D production based upon skin tone alone (page 102). This is due to the other factors, including genetics which influence an individual’s ability to produce Vitamin D. Also interesting to note, from the same link above on page 106, is that low Vitamin D levels in African Americans are not related to with increased risk of bone fractures as they are for other ethnic groups. Why this is the case seems to be an area that is still being studied.

All that said, the Recommended Daily Allowance for Vitamin D is 600 IU/day for everyone from 1 year of age to 70, and 800 IU for those seventy and older. There are no separate recommendations based upon ethnicity or skin tone. I find a lot of variation in recommendations for sun exposure, and lot of hesitancy to recommend sun exposure due to concerns about skin cancer, but a fairly recent article from the Harvard Medical School relating to bone health and vitamin D (…/two-keys-to-strong-bones-ca…) says that 5-30 minutes outdoors in the sun twice a week with your face, arms, legs or back exposed is sufficient.

Calcium Supplements and Calcium Fortified Foods

Recently I was asked about the safety of calcium fortified foods. The person who asked the question was concerned because their physician had advised her to stop taking calcium supplements, and they were now unsure whether they should have foods that were fortified with calcium.

The short answer is, yes, according to the Institute of Medicine (IOM) the Food and Drug Administration, and a number of other sources, calcium fortified products are safe.

Now the long version:
Firstly, I want to say that if your doctor advises you to do (or not do) something, you should probably listen, and/or seek a second opinion from another physician. Without having access to a person’s medical records, and without being in the exam room for the conversation, I would be exceedingly presumptuous to comment on a doctor’s guidance related to a specific patient.

I do want to venture a guess at why the physician gave this advice, as I think it may shed some light on the question of safety. Speaking generally, some studies have shown an increased risk of heart disease related to calcium supplementation for adult women. However a recent study by the Brigham and Women’s hospital with more than 74,000 participants followed for 24 years, showed no increase in risk for heart disease for women using supplemental calcium.

That’s a huge amount of people followed for a long time by a very well-regarded institution, so I’m inclined to trust the results. The flip side is that calcium supplementation has not been shown to be particularly effective for reducing rates of osteoporosis in post-menopausal women. So if some studies suggest risk of heart disease, and most studies show no benefit for adults, why continue to supplement? I’m guessing that this may have been the basis of the doctor’s advice: Some indication of risk + no indication of benefit = why bother? Especially in terms of supplements, I agree with this approach. Taking dietary supplements should be done with a specific goal.

Back to the question at hand: Is supplemental/fortified calcium safe for children? The Institutes of Medicine (IOM) sets the Tolerable Upper Limit (“A Tolerable Upper Intake Level (UL) is the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals in the general population”) for calcium at 2500mg for 1 – 8 year olds and 3000mg for 9-18 year olds. They don’t make any differentiation between sources (i.e. whole food, fortified food, supplements) in setting this limit.

The Office of Dietary Supplements (ODS), of the Department of Health and Human Services has a great page on Calcium. You can also find the Recommended Daily Allowances for different age groups there. You’ll notice that calcium recommendations are higher during the adolescent and teenage years. As children are growing into adults, they are making a lot of bone that will need to last them for the rest of their life, so this time is critical for calcium intake. Milk is a significant source of calcium, so for children with milk allergies or lactose intolerance, finding an alternative source for calcium is important. Other calcium-rich foods are the first option for filling the gap, followed by fortified foods, and then supplements.

As noted on the ODS Calcium page linked to above, it’s unlikely that you’ll get excessive calcium from food. Non-dairy milks and yogurts are often fortified to match the calcium content of the products they are similar to, so it seems unlikely that you would end up providing excessive calcium from those source. That said, take care with adding to many calcium fortified foods to a diet.

Lastly, I think this page from Berkeley Wellness provides good information as well:

Body Mass Index – Behind the Scenes

Originally for my post on the Body Mass Index (BMI), I wanted to include a BMI calculator directly in the post.  I found a WordPress plugin, PHP Code for Posts that allowed me to use PHP code in the post and coded the calculator.  Unfortunately, when I tried to put the calculator on the page,  I ran into an issue with how the variables are passed from the form to the function that handles the calculations.  The code works on it’s own, but embedded in a post it fails.  I ended up making a link to the URL where I had tested the calculator.  I’m hoping to find a better solution in the future.

Here’s the code, in case you’re intersted (formatted with Preserve Code Formatting). Normally, I’d pull the style sheet and HTML into their own files, but for the purposes of displaying the code I have them all together.


Body Mass Index (BMI) Calculator for Adults

'; function bmiForm() { echo '

'; if ((empty($weight)) && ($_POST['done'] == 'y') || (empty($feet)) && ($_POST['done'] == 'y') || (empty($inches)) && ($_POST['done'] == 'y')) echo '

Please complete all fields above.

'; } function bmiResult() { global $weight, $height, $feet, $inches; $BMI = number_format((($weight / ($height * $height)) * 703), 1, '.', ''); echo '

Your Body Mass Index (BMI) is: ' .$BMI. '

'; echo '

Based upon a height of ' .$feet. ' feet, ' .$inches. ' inches and a weight of ' .$weight. ' pounds

'; if ($BMI <= 18.5) { echo '

Your BMI falls in the "Underweight" category.

Understanding your BMI: BMI is not intended to diagnose a problem, but to indicate when follow up with a healthcare professional is a good ideas. It is possible for a person to be healthy with a BMI that falls outside of the Normal range. However, you should consider seeking the opinion of a healthcare professional or registered dietitian.

'; } elseif (($BMI > 18.5) && ($BMI <= 24.9)) { echo '

Your weight is normal.

Understanding your BMI: BMI is not intended to diagnose a problem, but to indicate when follow up with a healthcare professional is a good ideas. A BMI within the Normal range is associated with reduced risk of diseases, including diabetes and high blood pressure, which are more common in overweight and obese individuals.

'; } elseif (($BMI >= 25) && ($BMI <= 29.9)) { echo '

Your BMI falls in the Overweight category.

Understanding your BMI: BMI is not intended to diagnose a problem, but to indicate when follow up with a healthcare professional is a good ideas. A BMI within the Overweight range is associated with increased risk of disease, including diabetes and high blood pressure. While it is possible to be healthy with this BMI, you should consider seeking the opinion of a healthcare professional or registered dietitian.

'; } elseif ($BMI >= 30) { echo '

Your BMI falls in the Obese category.

Understanding your BMI: BMI is not intended to diagnose a problem, but to indicate when follow up with a healthcare professional is a good ideas. A BMI within the Obese range is associated with increased risk of disease, including diabetes and high blood pressure. While it is possible to be healthy with this BMI, you should consider seeking the opinion of a healthcare professional or registered dietitian.

'; } else { echo "

Sorry, something went wrong

"; } } if ((isset($_POST['done'])) && ($_POST['done'] == 'y') && ($_POST['inches'] != NULL) && ($_POST['weight'] != NULL) && ($_POST['feet'] != NULL)) { bmiResult(); } else { bmiForm(); } echo '

This calculator is intended for use by individuals over 20 years of age. More Information about BMI from the Centers for Disease Control and Prevention

'; ?>

Body Mass Index

Body Mass Index (BMI) is frequently misinterpreted.  Looking around the internet you’ll find plenty of articles and blog posts talking about its failures.  Often, the key complaint will be that it can misidentify very muscular individuals as being obese. Additionally, BMI doesn’t take frame size into account, which can be another important factor in assessing weight.  The complaints against BMI usually stems from a misunderstanding of the intended use of BMI.  The intent is not to attach a specific label to a individual,  rather it is used to evaluate populations, and as a screening tool in healthcare settings.

As screening tool, it’s intended to identify individuals who may be in need of further assessment.  In the hospital setting, dietitians may use BMI as one criteria for taking time to do a more in-depth review of the patient’s record.  The 2008 study Accuracy of Body Mass Index to Diagnose Obesity In the US Adult Population found that, when evaluating obesity,  the BMI has 95% specificity for men and 99% specificity for women.  This means that if the BMI indicates obesity its highly likely to be correct.  This is a great counter-argument against those who bring up false positives like the elite athlete.  The sensitivity of the BMI is low, so using it  as the sole evidence to rule out obesity would be a problematic.

So, what does the Body Mass Index say for you?


Magical Rice Preparation?

My wife brought and interesting article in the Washington post to my attention. An undergraduate researcher and his mentor at the College of Chemical Sciences in Sri Lanka report that they have found a way to reduce the calories in rice.

This is the process as stated in the article.

  1. Bring the water to a boil
  2. Add an amount of coconut oil equivalent to 3% the weight of the rice being cooked
  3. Add the rice and cook until complete
  4. Cool and store the rice under refrigeration for 12 hours
  5. Enjoy! (ok, I added this step)

According to the article, this cooking process converts some of the starch in the rice to resistant starch. This is important because resistant starches cannot be broken down by the human digestive tract. Because of this there would be a decrease in calories from carbohydrate. Sounds pretty good, right?

The article suggests that this process could reduce the calories in a given amount of rice by as much as 50%, but then goes on to say this:

So far they have only measured the chemical outcome of the most effective cooking method for the least healthful of the 38 varieties. But that variety still produced a 10 to 12 percent reduction in calories. “With the better kind, we expect to reduce the calories by as much as 50 to 60 percent,”

So, I see some pretty big issues here:

  1. So, lets say you want to make a cup of rice. You need about 56g of dry rice, That’s going to be about 204 Calories. A 10-12% reduction in Calories saves you about 20 to 25 Calories. Ok, but you’ve also added about 3% of the weight of the rice as coconut oil, 1.68 grams at 9 calories a gram for a total of a little over 15 calories. Your net calorie reduction is somewhere between 5 and 10 calories, or somewhere between 2-5% reduction.
  2. They’ve tested 38 varieties of rice but only have results for one, which seems a little odd. Where does the claim for up to 50-60% reduction come from then? Why did they lead with the least healthy?
  3. Let’s say there’s some support for the the 50-60% claim. Would you want to consume rice that was made up of 50-60% resistant starch? My guess is “Maybe”. Just because you can’t digest the resistant starch doesn’t mean the bacteria in your gut can’t. This would be a field day for them. Assuming the same portion as in 1), that would be about an ounce of resistant starch bacteria chow in your gut. A recent study showed a “mild but significant”(1) increase in flatulence in test subjects receiving 40 grams of resistant starch as part of a test protocol. That said, a number of recent papers have shown health benefits for consumption of resistant starch, so maybe a little extra flatulence will turn out to be worth it.
  4. Some may argue that any reduction in the glycemic index of the rice would be a benefit, but a better route to reducing the glycemic index of starchy foods is to make sure you consume them with fat or protein.

So the short version of all this is that the researchers are promising a lot, but what they’ve measured so far is pretty small. 5-10 Calories isn’t particularly significant in terms of an entire day, or even a meal. You’d be better off having more vegetables and less rice the next time you make a dish involving rice.  Maybe the increase in resistant starch would be beneficial, but it seems pretty modest as well.  Focus on bananas, oats, and legumes until they  prove their claims.


Slow Down in Posting

I’m still working on writing blog posts, but my work time has recently been absorbed by another project. As a result I haven’t posted in way too long. I’m currently in the process of developing an application to assist the family and caretakers of a young girl with an Inborn Error of Metabolism (IEM) in tracking key nutrients in her dietary intake.

IEMs dramatically alter the way the the human body processes nutrients. The conditions can be very serious, and are potentially fatal. Strict management of dietary intake is required. It takes an incredible amount of effort.

Out of respect for the family’s privacy, I won’t be discussing the specific situation. Hopefully, once I get out of the first stages of development, I’ll have more time to devote to this blog.

Measuring in Recipes

When your first learning to cook by following recipes. it’s important to measure. It takes a lot of practice to get familiar with the ratios of ingredients that make up a good recipe. Later on you get to be more lax. You make mistakes and learn by experimentation. In the end though, it may be useful to measure the ingredients that are going to be most important to you.

Fats – It can be easy to add a lot of oil to a food you are cooking. 1 tablespoon of fat contains about 120. Fats are the most dense source of calories, containing about 9 calories per gram, compared to about 4 calories per gram from protein and carbohydrates, and about 7 calories per gram from alcohol. If you watching calories, monitoring the amount of fat you add while cooking is a good idea.

Salt – 1 teaspoon of salt is 97% of the Recommended Daily Allowance (RDA). It’s a challenge to keep below 2300 grams a day as the United States Department of Agriculture (USDA) advises, since so many of the processed foods that are common in America are high in sodium. The USDA advises using no added sodium when cooking. I’d rather try and reduce the amounts of high-sodium processed foods in my diet and use salt carefully when I cook.

Meat – Lean meats are a great source of protein, but how much do we really need? The RDA for protein is 46 grams of adult females and 56 grams for adult males. Each ounce of cooked meat contains about 7 grams, so about 7-8 grams of meat is all we need in a day. Getting more than the RDA isn’t a big deal so long as the protein comes from vegetable sources like beans, rice and tofu. Animal sources of protein tend to add saturated fats and cholesterol to our diets which we want to avoid, and are a strain on the environment. So both for ourselves and the planet, I think it’s worth-while to be aware of how much we are eating by measuring when we cook.

Facts of Flavor: A Series

I’m starting an ongoing series of posts I’m going to call “Facts of Flavor”.  I want to dig a little deeper into good culinary techniques and talk about how good technique creates great tasting food, with an emphasis on how we can use good technique to create healthy food, as well as the occasional treat.

Here are some of the topics I plan to cover

  1. How the human body senses taste and flavor, and how the two interact
  2. Just enough organic chemistry technique to understand some of the things that happen as we cook
  3. The roles that different foods play as we cook
  4. The scientific basis of good technique
  5. Whatever else seems to fit

I’m hopeful to come up with some fun experiments you can do to see the difference that technique can make as well.  I’ll be kicking the whole thing off in the next few days by starting to talk about our sense of taste.

I hope you’re having a great holiday season, and that you follow it up with a happy new year! Stay tuned!

Vermouth Steamed Green Beans

In my last post I talked about the ways that dry vermouth can be used in cooking, and said I’d follow up with an example.  This is a fairly simple recipe, which uses the sweetness of the vermouth and shallots to compliment the flavor of the green beans.

Picture of green beans from recipe

Fresh green beans, lightly steamed with dry vermouth

Cooking Time: 20 minutes

Yield: 4, 1 cup servings


  • 1 tablespoon olive oil
  • 3 tablespoon diced shallot (or substitute 1 teaspoon garlic)
  • 1 teaspoon dried chili flakes1 pound fresh green beans, trimmed
  • 1/4 cup dry vermouth

Recommended Equipment:


  1. Heat the olive oil over medium heat on the stovetop
  2. Add the shallot and chili flakes.  Saute until the shallot becomes translucent
  3. Add the green beans stir to coat with oil
  4. Allow the green beans to cook for about 5 minutes, sirring once or twice. Be sure to scrape the bottom of the pan to move the shallots, or they may burn
  5. Add the vermouth and cover the pan
  6. Cook for another 5 minutes until the beans have turned light green.
  7. Uncover and cook for another 2 minutes to allow more of the alcohol to evaporate
  8. Serve immediately, or cover and hold over low heat.
Nutrition Facts
Calories 80.52   Calories from Fat 31.5
% Daily Value
Total Fat 3.5 g 5%
   Saturated Fat 0.5 g 3%
   Trans Fat 0 g
   Cholesterol 0 g 0%
Sodium 9 g 0%
Total Carbohydate 11.05 g 0%
   Dietary Fiber 4.025 g 16%
   Sugar 2.275 g
Protein 2.3 g 5%

Food Safety:

Cool below 70° within 2 hours, and below 41° within 4 hours.  Store for up to 7 days under refrigeration (less than 41°).