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Caffeine Facts for Women
FACT: Iron deficiency, inadequate calcium intake, osteoporosis, and depression are devastating problems for women.
Fact: Caffeine dramatically reduces iron absorption.
Fact: Caffeine increases calcium loss and risk of osteoporosis.
Fact: Caffeine produces shortterm mood elevation, but contributes to rebound depression.
Reduced Calcium Absorption
Over 65 percent of American women have low calcium intake, a condition that is aggravated by caffeine’s ability to accelerate the loss of calcium through the urinary and intestinal tracts.
One recent study provides a smoking gun to implicate caffeine in calcium deficiency. Researchers at Central Washington University investigated consumption levels of calcium and caffeine in women thirty-one to seventy-eight years old. All women consumed approximately 200 milligrams of caffeine daily, “the equivalent of one to two cups of coffee.” This study showed that total urine output of water, calcium, magnesium, sodium, and potassium increased significantly for more than two hours following caffeine ingestion.11
Osteoporosis
Even with this conclusive evidence of caffeine-related mineral loss, health authorities hesitate to affirm that caffeine is a risk factor for osteoporosis. That’s because the caffeine industry has created a smokescreen around the issue, using studies that supposedly show that no danger exists. Let’s take a closer look.
One study commonly cited by caffeine proponents is titled “Caffeine Does Not Affect the Rate of Gain in Spine Bone in Young Women.” But if you read the study itself (and not just the title) you will find that the subjects were college-aged women who consumed one cup of coffee per day. To say the least, this level of caffeine intake is representative neither of college students nor of most other American adults. Even the authors admit that the study does not in any way vindicate caffeine. They state only that “one cup of coffee per day, or 103 mg, appears to be safe with respect to bone health in this age group.”12
Surveys suggest that most American women consume that much caffeine before noon.
Besides, if you’re trying to evaluate risk of osteoporosis, wouldn’t it be important to look at postmenopausal women? Researchers at the University of California in San Francisco who did just that found a significant association between caffeine consumption and reduced bone mass. In fact, the caffeine—low bone density connection was found even in those women who took calcium supplements.13
Another way to explore the issue is to study middle-aged but still premenopausal women. In this category, leading researchers found that caffeine intake produced a double whammy on calcium levels. The drug increased calcium lost in the urine and increased calcium loss through the intestinal tract.
Again, the amount of calcium lost was directly proportional to the amount of caffeine consumed.14
For the skeptic who wants to see proof that such calcium loss results in greater risk for osteoporosis, a very recent study conducted with women aged forty to fifty found that caffeine intake was conclusively associated with decreased bone density,15 and research by the United States Department of Agriculture confirms the findings. Results from the USDA study indicate that women who consume less than the RDA for calcium (65 percent of all women in the United States) face dramatic reductions of bone strength, especially when
they consume more than two or three servings of coffee per day.16
Another research strategy is to take habitual caffeine users and see what happens when they stop. As expected, after only two weeks off caffeine, women showed significant improvements in calcium status even while consuming a lowcalcium diet.17
Still another perspective (if you need one) may be gained by looking at the association of caffeine intake and hip fracture. Sure enough, data from studies covering nearly 90,000 U.S. women show a positive correlation between caffeine intake and hip fracture. The largest of the studies found that the risk for hip fracture for those who consumed the most caffeine was three times (300
percent) greater than it was for the group that consumed little or no caffeine.18, 19
There are actually two contributing factors that weaken a caffeine user’s bones. We’ve discussed the direct factor of increased calcium loss, but there are also indirect factors associated with the increase in stress hormones. Caffeine raises cortisol levels, and with daily intake, that stress hormone may remain elevated for long periods of time. We also know that caffeine contributes to depression, and the combination of these two factors has telling effects. Women with a history of depression, for example, have weaker bones compared to agematched women without depression.20 Again, this is due simply to the chronic elevation of stress hormones that is part of the caffeine/depression scenario.
The goods news is that medical review articles are finally listing caffeine as a risk factor for osteoporosis.21–22, 23, 24, 25, 26, 27 The bad news is that no one seems to be paying attention. Material from the National Women’s Health Network states that the negative effect on bones from a cup of caffeine is “more than adequately offset by a tablespoon or two of milk,” and the position statement by the National Osteoporosis Foundation in Washington, D.C., states, “If calcium intakes meet NOF standards, NOF considers caffeine intake in the range of 2–4 cups of coffee per day to be without harmful effect on the skeleton.” I do not mean to denigrate these organizations, both of which provide an extremely valuable service. It’s just that in regard to caffeine, they are, like almost everyone else, unwilling to examine the evidence.
Caffeine, the Iron Robber
Not only does caffeine contribute to the loss of calcium, magnesium, zinc, and other valuable minerals, but it also contributes to serious iron loss. The data is incontrovertible. A 1983 study showed that one cup of coffee “reduced iron
incontrovertible. A 1983 study showed that one cup of coffee “reduced iron absorption from a hamburger meal by 39%.” The study went on to state: When a cup of drip coffee or instant coffee was ingested with a meal …
absorption was reduced from 5.88% to 1.64% and 0.97% respectively, and when the strength of the instant coffee was doubled, percentage iron absorption fell to 0.53% … The same degree of inhibition as with simultaneous ingestion was seen when coffee was taken 1 hour later.28
I must explain the consequences of this astounding finding. Most women spend their entire lives malnourished in iron, and nearly 30 percent will be frankly anemic until they stop menstruating. This is because it is very difficult to absorb iron from food, and unless a woman has a great diet and perfect digestion, her monthly blood loss will tend to exceed her absorption of this essential mineral.29
Add caffeine to that equation and the likelihood of insufficient iron approaches certainty. Depending on the composition of a meal, a caffeinated beverage can reduce iron availability by a whopping 50 percent.
What’s more, caffeine impairs the absorption of any iron supplement taken to correct the deficiency. Documented cases have appeared in the medical literature showing that anemia wasincurable until the patient stopped consuming caffeine.30
”Considering the high incidence of iron deficiency anemia worldwide and its likely association with immune function and mental development, these findings indicate that dietary habits such as coffee and tea consumption deserve as more attention potential causative factors.”
Source: American Journal of Clinical Nutrition, 1988;vol. 48:645–51.
As you might know, the statistics on iron deficiency are alarming. Research shows that iron deficiency is the most common nutritional deficiency in the United States, Canada, Australia, and western Europe.31 But what exactly does that mean? We’re used to hearing about “iron-poor blood” causing a certain lack of zip and energy, but iron deficiency is much more than that. In fact, there are three distinct levels of iron deficiency, and I’ll bet you’ve heard only about one.
Don’t feel bad. Your doctor may not know any more about this important issue
than you do
.
Anemia as a Measure of Iron Sufficiency… and Other
Myths
Imagine that you had a financial adviser to manage your estate. One day, he calls you and announces that you will have to file bankruptcy because you are broke.
“What?” you exclaim. “How is that possible? When you started managing my account, I had two million dollars!” “Well,” he says, “about three years ago, I put all of your money in a gold-mining operation. Over the years, it has done quite poorly.” “Why didn’t you tell me I was losing enormous sums of money for three years?” you ask. To which he replies, “Well, technically speaking, you weren’t completely broke, so as long as you had some money, I didn’t think of bringing it up.”
If this scenario sounds absurd and unbelievable, you have to understand that most doctors have followed this approach for decades with their female patients in regard to the precious commodity known as iron. That’s because doctors have been looking only at the woman’s complete blood count (CBC). If she’s anemic (bankrupt), they tell her. If she’s not anemic, they let it slide. The fact of the matter is that a woman will typically be iron deficient for two to three years before she becomes anemic.32 At that point, anemia is difficult to cure. But if iron deficiency is identified in its early stages, it can easily be treated and anemia avoided.
Shocked reader: “It must be that there is no reliable way of determining the early stages of iron deficiency. “ Ah, but there is. It’s a simple and inexpensive blood test that measures body stores of iron, called serum ferritin.
Shocked reader: “But my doctor does measure serum iron, and he always told me it was normal.” Serum iron is a meaningless test. It only tells you how much iron is traveling through your blood. You can be frankly anemic—hardly able to get out of bed—and have normal serum iron.
Shocked reader: “Gosh, this serum ferritin must be a new test.” Actually, the test has been available for nearly thirty years. Studies confirming its value as the definitive test for iron status were published in 1979, and verified repeatedly for the past two decades.33–34, 35, 36, 37 By now, the consensus among experts is that the only accurate way to determine iron nutriture is by evaluating ferritin and other iron parameters. What’s more, serum ferritin is also the only iron indicator
that is able to differentiate between true iron deficiency and anemia due to infection.38
Shocked reader: “If this is such a critical issue, why in the world has it not been diligently pursued?” Well, iron deficiency is primarily a problem for women, and most physicians and researchers are men. Additionally, the cure for the problem is a nutritional supplement and not a prescription drug, so the issue doesn’t get much attention. There is, however, a growing body of research showing that ferritin is a critically important factor in evaluating (and even preventing) atherosclerosis,39 so we may yet see the test performed routinely.
The takehome message here is that there is a progression of iron deficiency.
You’re not optimally nourished in iron one day and anemic the next. It’s important to have a sensitive marker for iron status because there are clear symptoms way before the anemic state. Most symptoms are related to energy and mental alertness, so the connection with caffeine is more than casual.
For example, a woman with low iron stores is likely to have low energy and a hard time concentrating. Chances are she will also be depressed. And since she doesn’t know these conditions are related to malnutrition, she will most likely chalk it up to growing older or her personality. What’s more, she will probably resort to using caffeine in order to cope with these feelings, and that brings us to the next vicious cycle:
Iron Alert Action Plan
1. Monitor your serum ferritin level starting at menarch (the onset of menstruation). Make it a part of your yearly physical, or test at least every two years. Use the following guidelines derived from the latest bio-medical information:
Ferritin Level
Iron Status
0–10
Severe iron deficiency
0–18
Marginal iron deficiency
18–40
Adequate
40–100
Optimal iron nutriture
2. If your ferritin is less than 10, I suggest that you work with your physician to correct the problem. You will need an effective iron supplement and follow-up. The most bioavailable form of iron I have found is a chelated iron, known as iron glycinate (see Appendix A). But be careful. Too much iron can cause constipation and abdominal cramping. This can be avoided by staying in the 30-to-90-milligrams-perday range.
3. If your ferritin is between 18 and 40, premenopausal women should still consider iron glycinate at 30 milligrams per day.
4. In all cases, it is imperative that you maximize iron absorption from the food you eat, and that means reducing caffeine intake. If you continue drinking coffee, tea, or soft drinks with meals, the caffeine will reduce absorption of iron from any tablet you take as well as the meal. The only sensible approach is to get off the caffeine and soft drinks. If you’re drinking tea, have it at “teatime” (midmorning or midafternoon), not with meals. Caffeine-free herbal coffee and herb tea, of course, will not interfere with iron absorption.
5. Vitamin C has been shown to enhance iron absorption. If your supplement does not already contain vitamin C, take a 200milligram tablet of vitamin C with your iron.
6. Avoid other iron robbers: sugar, high doses of calcium supplements (especially calcium carbonate), phytic acid (wheat bran), and oxalic acid (spinach, beet tops).
Suboptimal Iron Affects Mind, Mood, and Learning
Researchers at the Johns Hopkins School of Medicine, recently highlighted an important defect associated with suboptimal iron status. In their study, seventy-three anemic girls who were “merely” iron insufficient were selected from four Baltimore high schools. They took either an iron supplement or a placebo for eight weeks. In just eight weeks, there were remarkable differences between the treatment group and the placebo group in memory, attention, and learning skills.40 It turns out that iron is essential for the activation of enzymes that turn on key brain functions, including the secretion and activity of serotonin and dopamine, two neurotransmitters that affect mind, mood, and behavior. We now know that even marginal iron deficiency—what I call iron insufficiency—can contribute to mood, memory, and learning disorders long before anemia ever develops.
Premenstrual Syndrome (PMS)
Almost one-third of premenopausal women suffer from some degree of PMS—and recent research has confirmed that caffeine intake is related to both its presence and its severity.41 Basically, the more caffeine you ingest, the worse your PMS will be.
One study, based on 841 responses to a questionnaire sent to female university students in Oregon, showed that caffeine consumption—whether coffee, tea, or soft drinks—was strongly related to PMS. The association started at one cup per day, and those consuming eight cups per day were seven times more likely to suffer with PMS as compared to abstainers.42
Ironically, women often try to deal with that worn-out feeling and other symptoms of PMS by increasing their caffeine consumption, which only makes the problem worse. One study confirmed that women with moderate or severe PMS have markedly different patterns of caffeine consumption than women with few or no symptoms.43 And what about that depressed feeling that so often accompanies PMS? You guessed it: Episodes of depression during the luteal phase of the menstrual cycle have been linked with elevated cortisol and caffeine consumption.44
I urge women who suffer from PMS to prove or disprove these findings in the laboratory of their own bodies. Try eliminating all caffeine from your diet for a few months (it will take at least two months for a fair test). Then drop me a card, E-mail, or fax with your findings so I can tabulate the results.
card, E-mail, or fax with your findings so I can tabulate the results.
RESEARCH CAPSULE Tea
Drinking Linked to PMS
; A team of Chinese physicians and Annette MacKay Rossignol, an epidemiologist from Oregon State University, measured tea consumption of 188
women nursing students and tea factory workers in China Over 90 percent of these women rode bicycles every day, and none used alcohol, tobacco, or oral contraceptives. Their diets were virtually identical: vegetables, rice, pork, no beef, and very little refined sugar. Approximately 40 percent of the nursing students reported PMS, but in the tea factory, where much more tea was consumed, nearly 80 percent reported PMS. Women who consumed more than 4.5 cups of tea per day were almost 10 times as likely to suffer from PMS as women who drank none.45
Menopause
If you are suffering from (or trying to avoid) the negative side effects of menopause, you’ll be very interested to know that caffeine is associated with decreases in levels of estradiol.46 In other words, the more caffeine you consume, the lower your estradiol—and the more likely you are to experience the concomitant changes associated with low estrogen production.
In addition, caffeine ingestion also tends to lower blood levels of bioavailable testosterone in women, and raises levels of sex hormone binding globulin.47
Since testosterone contributes significantly to a woman’s libido and sense of strength and power, the result of these hormone changes at menopause may include androgen (testosterone/DHEA) deficiency and a decreased zest for life.
For women just entering menopause, caffeine is a significant factor in determining whether the experience will be easy or difficult. Research shows that during this period (known as perimenopause) a woman becomes more sensitive to the stimulant action of caffeine. Blood pressure, heart rate, and stress response (together known as cardiovascular reactivity) are all greater compared to premenopausal women.48 In addition, caffeine appears to be a factor in the incidence of hot flashes. Research shows that eliminating caffeine can help reduce both the number of hot flashes and their intensity.49