#29 Is it a coincidence that a female's menstrual cycle is equivalent to the moon's orbital period? Are they connected?

This question comes from Tom S. via the blog.

There are a couple things in this question I want to address. First, if it is a coincidence it is not connected. In science there is a concept of "coincidence or correlation does not imply causation or connection". There is a great humor blog called Spurious Correlations that shows that you can make anything correlate.

That aside, the second and more important concept to address is that this assumes all women have the same menstrual cycle. This is an assumption that is often made but not reality. What it comes down to is that this concept is comparing two estimates as if they are real, measured and accurate numbers. I think this is what we will address, as well as the moon cycle itself.

How long does it take the moon to orbit the Earth?

This in itself is a complicated question because the moon phase appearance is influenced by the moon orbiting the Earth and the Earth orbiting the Sun. The moon orbits the Earth in just over 27 days. However, it is 29 and a half days for the moon to pass through all the phases. (Discussion of Lunar cycles) Which of these would we consider the moon cycle? The 28 days we usually hear is an average of these two time lengths. (We will see in this discussion that a lot of common knowledge on the subject is based in comparing multiple averages and not real numbers.) In truth, every common calender lists the moon cycle as 29.5 days and not the 28 that we associate with the menstrual cycle. You can read about all the calender relations and much more on lunar cycles here.

The female cycle

There is a huge misnomer in common knowledge that a female cycle is fixed at a certain number of days. This is not true. The length of a female cycle changes for many reasons and may change over a woman's life time. To this discussion I think it is important to look at some of the many things that can change the length of a woman's menstrual cycle. Most women fall in a 21 to 35 day cycle while it is not uncommon for women to exceed the 35 days as well. This time period is for the average woman without the influence of medications, such as birth control, or other influences from the list we will be discussing below. Of those 21-35+ days, 2-7 days is spent bleeding. This is the numbers for adults. However, for teens and pre-teens the range is even greater and may be 21-45 days or longer between periods.

Circadian Rhythm and Sleep

Our natural internal rhythms can alter the frequency and duration of a menstrual cycle. Sleeping excessively or not enough can have an impact on menstrual cycle length. Chronic insomnia can affect the length of a menstrual cycle causing a woman's normal cycle to be longer than the 35 days at the upper end of the average. Melatonin levels can change the length of a cycle too. This is important because of the use of over-the-counter melatonin for sleep which makes this influence more common than in the past. There is plenty of research that shows sleep rhythms can have such an effect on the cycle that it can impact fertility.
A research paper about circadian rhythms and menstraul cycle

Eating and Weight

The amount one eats can impact length of menstrual cycle. Decrease in food due to starvation, be it external such as famine or internal such as anorexia or bulimia, can  decrease the frequency of menstrual cycles. In some cases lack of food can eliminate the menstrual cycle completely. On the other side, over eating and being obese can decrease frequency of menstrual cycles. Types and quality of food can also affect menstrual cycle duration. Other things such as alcohol and caffeine consumption can alter period length.
Research paper weight and sex-hormones
Research on anovulation
Bariatric surgery and menstrual/fertility issues

Exercise

Intense exercise can alter fertility and menstrual cycles as well. Called exercised induced Amenorrhea, this is a complete lack of menstrual cycle but it can also be a decrease in frequency.

Medications and Illness

A large number of illnesses can affect period duration. Everything from anemia to uterine cancer can alter menstrual cycles. Medications can also affect the duration and intensity of menstrual cycles. Many mood stabilizing medications such as anti-depressants can increase or decrease the length of menstrual cycles.
Diseases and conditions that are effected by or affect menstrual cycles.

Age

Young and old women both experience irregular menstrual cycle lengths. Between the ages of 25 and 40 women experience the most regularity in periods. Prior to the age of 25 menstrual cycle irregularity is related to the hormone imbalances related to sexual maturity and development. After 40 the irregularity is due to peri-menopause.

Stress Levels

High stress levels can trigger less frequent or erratic menstrual cycles. At the root of this is the body mechanism, the same one in play with starvation, that signals that this is a poor time to conceive a child.This body stimulus can reduce the amount of menstrual cycles, which reduces the number of ovulations or chances to become pregnant.
Stress and Menstration
Affects of stress on women's health
Research paper on job stress and menstrual length

Other considerations.

The often cited study by Winnifred B. Cutler in 1980 that is used as proof that women's cycles are related to the moon doesn't prove anything. In the study it was shown that 40% of the studied women had a period start within 2 weeks of the full moon, i.e. within half a month of the full moon. The two week time frame is very large considering this is half of the entire moon cycle. The other thing to consider is most of the women, 60%, showed no relationship at all with time of period and full moon.

More reading:

Exercise and weight and menstrual cycles
Missed periods, exercise and osteoporosis
Stress, ovulation and bone health
List of everyday things that can affect periods.
Causes of Amenorrhea
The moon and activities
Moon cycle length and estrus length in multiple animals.
Do women who live together actually synchronize?

#25 What is lactose intolerence?

I think we should start with defining some things first. Lactose is a type if sugar found in dairy products. Lactose intolerance is a word that is often misapplied to a wide variety of conditions from dairy allergies, milk fat intolerance and the actual intolerance of the lactose sugar. Commonly people will apply the term lactose intolerance to anyone who has difficulty with milk products.  All of these conditions have varied intensity depending on the body.

Does dairy cause lactose intolerance?

No. Dairy does not cause lactose intolerence.  Any of the above definitions of lactose intolerence have a biological and often genetic deficiency in the body that interacts with the presence of milk. The condition itself is not caused by milk.

What is lactose intolerance?

Someone who has lactose intolerance either doesn't produce enough lactase or produces no lactase at all. Lactase is an enzyme that breaks down lactose. Someone who doesn't produce enough may just feel a little nausea when dairy is consumed. Someone who produces no lactase may have severe symptoms such as vomiting,  fever and diarrhea.  Several over-the-counter medications exist to help individuals consume dairy without issues.

More info on Lactose Intolerance as a Digestive Disease 

What is an intolerance to milk fat?

There isn't much research on milk fat intolerance but the research available suggests that approximately 5-9% of those who believe they have lactose intolerance may have both lactose and milk fat intolerance or just a milk fat intolerance. Since research is very limited it is hard to say much more about this condition.

What is milk allergy?

An allergy means your immune system has labeled an otherwise harmless substance as something that is dangerous to the body. In the case of dairy allergies it is usually one of the proteins that trigger the allergy. When a non - allergic person consumes dairy the body simply digests it.  When an allergic person eats dairy they digest it but one or more compounds in the dairy triggers an immune response. This immune response can be mild, sometimes termed milk or dairy sensitivity.  In some the immune response can be so intense that it can cause severe illness or even death.

Milk allergies are also most common in children. Most often the milk allergy develops before one year of age and most children grow out of the allergy by 4 or 5. Findings have shown that some infants produce large quantities of antibodies that are related to one or more types of milk...cow and breast milk allergies are the most common.

Sometimes the allergy persists into adulthood and allergy tests are required to determine which components of the dairy (sugars, proteins or fats) are causing the reactions do that diet can be more appropriately managed.

Common allergic symptoms include swelling of the lips, tongue or face or rashes, hives or skin irritation when one comes in contact with the allergen. In some cases anaphylaxis occurs or other life threatening symptoms such as airway constriction from the swelling.

Casein reactions and intolerance.
Casein is a large group of phospoprotein found in all mammalian milk. These proteins make up about 80% of cows milk and 45% of breast milk. Casein is present in many foods including dairy,  breads, pancakes, margarine,  non - dairy creamers and many other foods. Casein is present in higher quantities in dairy which means there will be a greater reaction to dairy products. This can often lead individuals to believe they have lactose intolerance. Casein allergy and intolerance is very uncommon some studies suggest 1% or less of the individuals who have reactions to dairy are reacting to casein.

Milk and other conditions
As a sugar lactose can interact with diseases where sugar is concerned such as diabetes. Other conditions such as Cerebral Folate Deficiency which interacts with the antibodies present in various types of milk, including breast milk. In addition some medication interact with or are less effective when taken with milk or with milk in the stomach. If you are ever concerned about any of these interactions you should be sure to talk to your doctor and pharmacist.

 More information:

Research on milk fat interactions with Lactose Intolerance

Information on Milk Allergy

Milk Allergy site geared toward helping children understand their allergy

Kid's Site about Lactose Intolerance

How to manage diet with a milk fat/Dairy/Dairy Protein Allergy

Huge list of sites, books, cookbooks, blogs and forums for lactose intolerance, milk allergies and casein allergies

Question #11: What does it mean to be Vegetarian? All the terms confuse me.

You are not alone in the confusion. Due to the wide range of diets considered "vegetarian" it can be difficult to sort through what people mean. I will try to define as many of the terms as I can to help you sort through this mess.

Vegetarian in general means that the individual avoids eating meat.

When most people say vegetarian they are referring to what is often called a Lacto-ovo Vegetarian. Lacto refers to lactose or milk and ovo to eggs. This is someone whose diet consists of plant foods and non-meat animal products. Non-meat animal products include milk products, eggs and honey. (There is a debate about Jello and gelatin though. As a product made of collagen from bones and other animal parts some vegetarians steer clear of it and others do not.)

Two closely related and more narrow diets fall under the traditional term vegetarian. These are vegan and raw food diets.

Vegans are those vegetarians who choose to eat no products derived from animals. These diets do not include eggs, milk products or, in most cases, honey. Vegans rely solely on plants for nutrition.

Raw Food diets can be vegan, vegetarian or in the gray area I will discuss below. Those on raw food diets choose to limit or eliminate cooking of foods because they believe this maintains the nutritional integrity of the food. As you can imagine, most of those on raw food diets avoid meat though some will eat sushi, kibbeh and/or carpaccio which are raw meat dishes. Many raw food diets also include honey and milk. In essence, raw food diet describes food preparation styles and not necessarily what types of foods are taken in. For example, someone who consumes only grains and raw fruits and vegetables would be on a raw food diet... another who ate raw fruits, raw vegetables, milk, yogurt, honey and grains could also be termed on a raw food diet. Yet the first individual is vegan and the second is a lacto-ovo vegetarian. (Hope that is not too confusing.)

Then there is a gray area. These are diets termed vegetarian but that do not fit the traditional (Standard?) definition of vegetarian. Many refer to these diets as semi-vegetarian diets.

Pescatarian are individuals who have the diet of a lacto-ovo vegetarian (or vegan in some cases) and in addition include fish and fish products in their diet.

Related there are diets where it will include all the lacto-ovo vegetarian diet plus chicken (and sometimes fish).

Venn Diagram of diets

These gray area diets spark a lot of concern for many vegetarians because it makes it more difficult to make themselves understood when it comes to discussions of dietary requirements. I have heard from many vegetarians (and have had this happen to me as well) express their dismay when they comment about being vegetarian only to have someone ask them if they would like fish or chicken.

Hope this clears up some of the terms associated with a vegetarian diet. Here at the end I've included  great resource from Harvard University that discusses all sorts of diets and diet concerns.


Resource: Harvard's The Nutrition Source

Question #10: Does eating sugar make you more likely to get sick?

A question from email and a complicated one.. the answer is yes... and well no.

One thing we must consider is the health of the person consuming the sugar in question. Those with immune diseases, diabetes, leukemia and digestive disorders (among other conditions) are going to have different experiences on health in this case than the average, healthy individual. Age and body size can also affect the case related to this question, partially, due to the body mass to sugar intake ratio. Of course a 40lbs child will be more effected by the large quantities of sugar than a 150lbs adult.

So, for the sake of this discussion we are going to assume that the individuals consuming the sugar is a healthy, average sized adult with no health conditions that will increase or decrease the effects of the sugar on the body.

The background

The only study discussing sugar and the immune system revolves around the behavior of neutrophils. Neutrophils are one type of immune cell found in the body. They are often in the blood but can also be found at sites of infection or cancer. These cells are usually the first ones to respond to infection or cancer due to their phagocytic nature, i.e. they come in and devour  the foreign or cancerous cells. There are several types of neutrophils that respond to different stimuli. The study does not seem to list which type(s) of neutrophils they are observing. This is problematic for deducing the actual impact of the sugar on the specific parts of the immune system.

The 1973 study I read started with individuals who have fasted. This means that they have not consumed food in 12-24 hours. Their body would be processing stored sugars at this point after exhausting the blood sugar (sugar in the blood). The subjects are then dosed with 20 or more teaspoons of sugar (different sources are used in studies such as honey, fructose, glucose, etc.) are then administered. After a wait time blood is drawn and added to a culture of bacteria. The neutrophil or other white blood cell activity is observed.

What did I find?

Aside from the 1973 study, which by science standards would be considered way out of date, I didn't uncover any scientific papers in peer reviewed journals that discussed humans and sugar intake. I was very disappointed as I searched around many distributors such as PubMed, EBSCOHost and several others and found nothing. I even tried different sugars to see if there would be papers for glucose or fructose instead of just sugar. I had no luck. I did find lots and lots of blogs and unreferenced sources that harken back to the 1973 study or no study at all.

What does that mean? Well there is one, outdated source, that suggest there may be a link. I say outdated because in most fields, particularly medicine, articles over 10 years old are considered sketchy to use and those 20 years or more are considered obsolete. The study suggests that it is the large inflow of sugar into the blood stream after fasting that depresses the immune system. The neutrophils are still working just a little slower.

Does this mean I will get sick from drinking a can of soda? No, probably not. Everything in moderation is how I have always felt. Perhaps with the recent interest in the subject more studies will be done to clarify what the outcome truly is. Below are links to the study and some relevant sources. Sadly, I can't give a better answer to this question until there is more research to read.


Sources:
Information about White Blood Cells
Blog Post about Immune System Cells
1973 Study most often cited
Blog post summarizing the study.
USA Today discussion of the study
Mouse Study - Note that the mice here are give 50g/kg of sugars which is much, much higher sugar to body weight dose than was used in the human study.
Another article that examines the study and raises the fact that no studies have really been conducted since 1973.
Another mouse study but it isn't only high sugar given but also high fat and cholesterol.