Discussion Board

As always, I very much enjoyed reading the newsletter. However, this time I wasn't quite sure about the statements on testing and interpreting vitamin D levels. I agree that often the standards are set rather high, which tends to promote disease mongering, but I'm not sure whether or not this is the case for vitamin D. John argues that sunlight is the source of vitamin D, so if you get enough sunlight, you should produce enough vitamin D. But is that really true? The real source of vitamin D is cholesterol, which under the influence of sunlight gets converted into vitamin D. Cholesterol is the precursor to all our hormones: estrogen, progesterone, testosterone, cortisol, DHEA, and yes also vitamin D. When you're on a low-fat, plant based diet, all cholesterol has to come from the body's own internal production (mostly by the liver). So, I can see a situation in which people on such a diet (this includes me, by the way) can run into vitamin D deficiency despite getting enough good quality sunlight. I'm thinking about situations of increased stress (more cortisol needed), strongly increased physical exercise (stress hormones and steroid hormones), and women in menopause (more steroid hormones needed). So, my question would be, how can we really know what is too low?

Tineke Grent-'t-Jong

Reading Dr. McDougall's writings, Dr. Welch's book Overdiagnosed, and hearing Dr. Hadler's lectures and reading some of his book, Worried Sick, the picture I'm beginning to so is that diagnosis and treatment (D&T) helps some people who really need it and harm some who really don't need it.

Of course, the ideal would be for D&T to be targeted accurately enough that it's only applied to the people who will really benefit. But that's not the world we live in. At this time in developed countries, the pattern these doctors are pointing out is that for every one person helped by D&T, some significant number are overdiagnosed/overtreated. And the more liberal the cutoff numbers become (the lower the cutoff for "normal" blood pressure, cholesterol, etc., and the higher the cutoff is made for vitamin D, HDL, etc.) the more people who would never develop disease from their "abnormal" numbers are pulled into the category of overdiagnosed/overtreated.

The recommendation for combatting this trend, as I understand it, is to stop looking so closely at the numbers for individual markers and pay attention to whether the body is manifesting disease. Maybe my vitamin D looks low according to the lab test. Am I having symptoms that one would expect from low D? If not, there may not be a problem.

Nothing is 100% in this world. Overreacting to perceived risks just puts us at greater risk.

"So, I can see a situation in which people on such a diet (this includes me, by the way) can run into vitamin D deficiency despite getting enough good quality sunlight."

I'm not sure how your statements two pieces fit each other. Why does a low fat plant based diet compromise the conversion of vitamin D? How does just being on this diet stop that process? We know that cultures, following a relatively close approximation of this diet have extended longevity. If anything the opposite seems to be the norm.
f1jim

As I said, cholesterol, not sunlight, is the precursor to vitamin D production. And cholesterol is also the precursor for all other hormones the body produces. Add to this the fact that the amount of cholesterol that the body can manufacture is limited and you get into the problem of "demand and availability". My reasoning was that, if, for whatever reason, the body is running low(er) on cholesterol, it will use the available cholesterol for the production of hormones that are most needed, and this might not be vitamin D. I don't know where vitamin D would fit the body's priority list for hormone production, but my guess is that it doesn't top the list (stress hormones likely have higher priority). Does that make sense to you? I'm also just brainstorming about this issue. Maybe "deficiency" wasn't the best choice in wording to describe a low vitamin D status; "insufficiency" would have been better. My point/question was how we can know what "too low" means.

I understood your points. But where do we start the chain of events in the process of vitamin D production? With cholesterol? Or perhaps the building blocks of cholesterol? Or perhaps in the cell structure process that builds the liver? In other words, a breakdown anywhere in the chain is a possible impact on vitamin D production. But that is true of any nutrient including absorption in the gut of various nutrients. We don't automatically assume a problem with these nutrients do we?
So you are asking the question that if we have no dietary intake of cholesterol are we at risk for vitamin D insufficiency? That was the point of my comment that the longest lived peoples have the lowest intake of animal proteins. I think that is an interesting point that bears some thought. If vitamin D deficiency adversely impacted lifespan would we see this relationship to longevity and animal protein intake?
What indication do you have that we are in any way running low on cholesterol? What indications are there that the liver is producing insufficient cholesterol? I just think it makes no sense to create a problem when we don't know one exists. It makes more sense to question a level unachievable through common sense approaches.
f1jim

I agree with you that there is indeed always the question where to start the chain of events. Also, I agree that there can be a breakdown anywhere in the chain of production of any nutrient, including absorption in the gut. I disagree that we don't assume a problem with other nutrients that are absorbed. For example, the ability to absorb nutrients in the gut is known, already for a long time, to decline with age. So even if you would still eat the same diet (no matter which diet that is), starting from the age of approx. 50 you would be more likely to run into deficits in some vital nutrients. This would of course especially be true for nutrients that are low or absent in the diet (e.g., vitamin D, vitamin B12).

You perfectly interpreted my question by the way: I'm indeed looking for an answer to the question whether low cholesterol can lead to low vitamin D status. I had my vitamin D levels tested recently and they were "low normal". I decided to try supplementing vitamin D for a while, just to see whether I would feel or see a difference. I did notice a difference in that it resolve an issue with increased blurry vision and light sensitivity. I had never heard of a link between these symptoms and vitamin D status and have yet to find any literature to support it, but it's an interesting observation. In addition, I noticed a slight increase in energy. So, who knows, maybe my vitamin D status was indeed not optimal (how would I know?). If I take into account a slightly higher stress level at the moment, because of my upcoming thesis defense and an increase in the amount of exercise I get, I was just wondering whether I could take this as a sign of unbalanced "demand and availability of cholesterol", the precursor of all hormones.

Has naturally (i.e., non-medicated) low cholesterol ever been shown to be detrimental? I would think, all other things being equal, the body would manufacture as much cholesterol as it needs for hormone production.

I think it's a big jump to go from the position that absorption declines with age to the position that no matter the diet you may be deficient in certain nutrients. That's a wide chasm and I am not sure it's supported by any data. If it is I'd like to see it. I agree many may be low on particular nutrients, especially on the SAD, but looking at the levels for most nutrients provided by this way of eating(excepting B12) shows more than adequate levels.
I remain open to research showing otherwise.
f1jim

In response to the last question: "Has naturally (i.e., non-medicated) low cholesterol ever been shown to be detrimental? I would think, all other things being equal, the body would manufacture as much cholesterol as it needs for hormone production."

There are numerous websites claiming that low total cholesterol might be just as detrimental to our health than high total cholesterol, but I don't know how reliable these reports are. Maybe John McDougall can comment on this? Are there any reliable scientific reports on possible negative effects of a too low cholesterol level, and how low is too low?

There are reports that show some cancer patients have a low cholesterol level. The consens seems to be that it's not the low cholesterol causing the cancer but jut the opposite...The cancer causing the low cholesterol level. It might just be the body wants the low cholesterol level when fighting cancer? Who knows.
f1jim

I'm not sure this is the same cholesterol that is ingested from eating meats.

According to wikipedia - it's 7-dehydrocholesterol that makes vitamin d and it's actually a zoosterol - a precursor to cholesterol - a steroid???
http://en.wikipedia.org/wiki/7-Dehydrocholesterol

And it seems to be more important that the 7-dehydrocholesterol is in the skin.

Well now I'm more curious - what kind of cholesterols are measured in a lipid panel? Are they all lumped together??? How many different steroids does our body make.

And instead of talking about it in the broad spectrum of cholesterol deficiency - wouldn't it be more accurate to talk about it in terms of 7-dehydrocholeseterol deficiency.

What covers this - organic chemistry???

Interesting.
Vic

I'm very curious about this topic as well as I just came from a doctor's appointment complaining of fatigue, and one of the suggestions was Vitamin D supplementation. I mentioned the newsletter article (though not in detail) and said that I would be willing to have my Vitamin D levels checked along with all of the other blood tests being done, but wasn't willing to supplement outright until getting the results back.

One thing the doctor (who was not my regular physician, but still holistic and supportive of my lowfat mostly-vegan diet otherwise) said that concerned me was that in order to get enough Vitamin D from sunlight, a person needs 85% of their skin exposed for at least 30 minutes a day. I said I didn't see how this would be possible or practical without daily nude sunbathing! She agreed and said this is why most people are low on Vitamin D.

This assertion sounded very fishy to me. My doctor's office is filled with holistic practitioners who do not usually buy into the fear mongering and over-prescribing of many Western doctors, but I'm skeptical that even with my medium-tan skin I cannot get enough sun in sunny San Francisco to have adequate Vitamin D levels without supplementation.

Anyway, we'll see when I get the lab results back if I have low levels or if my persistent fatigue might be caused by something else. I hate taking supplements (other than B12) and am eating iron-rich foods, so I doubt I have anemia, but we'll have to wait and see.

Just a couple more thoughts on this issue:

1) Getting enough sunshine per day might be doable in San Francisco, but it certainly is not possible where I live, in the Netherlands! Even if the sun is shining for us, it often isn't strong enough to help with vitamin D production in the skin (despite our fair skin adaptation!). Therefore, Dutch doctors recommend all citizens - independent of diet - to supplement vitamin D during the months that the sun is not strong enough, which boils down to months that contain an "r" in their name (i.e. from early September to late April). In addition, vitamin D is added to all dairy products and dairy substitutes.

2) Knowing your vitamin D levels is only part of the story, if you have symptoms that could signal some deficiencies you might also want to know your serum calcium, your phosphate and magnesium levels, maybe even your parathyroid hormone levels, because they are all related. Knowing the whole picture is more informative and can provide a better answer as to whether to supplement vitamin D or not. In general though, if you have no symptoms, don't even consider checking your vitamin D status. Why would you want to know if you don't want to treat it anyway if it turns out to be low?

3) What is regarded as "too low" is very dependent on a populations normalized values. Just to give an example, a cholesterol of 100-120 would be very low in the USA, but not in rural China. In other words, these values are very relative. As already mentioned by "TominTN" earlier: "The recommendation for combating this trend, as I understand it, is to stop looking so closely at the numbers for individual markers and pay attention to whether the body is manifesting disease." Very wise words.

4) I can recommend to keep a daily diary of how you feel in general. If there is a downward trend over a substantially long period of time, start looking for ways to reverse that trend. You don't have to be technically ill to work on optimizing your health! Who knows, maybe supplementing vitamin D, vitamin B12, or omega-3 fatty acids (preferably in the form of algae-derived EPA/DHA) for a while brings you back up to a more optimal health level.

Checking serum magnesium levels will not tell you if you have a magnesium deficiency since only 1% of your magnesium stores are in your blood.

[This is according to the book "The Magnesium Miracle" written by Carolyn Dean, M.D., N.D.]