Sleep Differences in African Americans

There are racial disparities in sleep with African Americans having a shorter sleep duration, a harder time falling asleep, and a tendency to wake up more easily after falling asleep.  There is also a decreased ability to phase shift African Americans sleep cycles when exposed to jet-lag and shift work situations, and the total duration of the cycle was smaller, a study by Eastman and colleagues at Rush University Medical Center found.  Sleep differences in African Americans cause a good deal of suffering.

These researchers surmised that the differences in sleep architecture grew from thousands of years of genetic modifications resulting from, for African Americans, exposure to year-around consistent 12-hour light-dark cycles, versus whites coming for northern regions with significant variability in the day length, dawn, and dusk times.

For example, in Ohio the day length changes from as short as eight hours in the winter to as long as sixteen hours in the summer.  Ohioans are constantly adjusting to time shifts. With thousands of years of exposure to time changes, Ohioans would develop an increased ability to tolerate the changes.  Closer to the equator (like western Africa), the time doesn’t shift nearly as much. The days are 12 hours long all year and there is no need to have an ability to tolerate time shifts.

Therefore “the shifting circadian periods in non-equatorial regions left a genetically modified increased tolerance for variable light-dark productivity hours.” Put simply, people who genetically come from regions near the equator are less able to adjust to time shifts, daylight savings times, jet lag, or anything else that causes a shift in sunrise and sunset.

Everyone has a “circadian period” which is an innate sleep wake cycle.  We also have an ability to shift that cycle somewhat.  People whose genes come from northern areas of the earth (Europe, Canada, etc.) have an ability to tolerate shifts in time whereas those of us from Caribbean, African, South American regions have much more difficulty adjusting.

In another study, researchers exposed African Americans and White Americans to a 9 hour delayed light/dark sleep/wake and meal schedule, similar to traveling from Chicago to Japan.  Essentially what would take 10 days for full adjustment in White Americans, would take 15 days for African Americans to adjust.

Swing shifts are bad for your health!

The need to adjust to time zone changes is only occasional in most people, and there are methods to make this adjustment smoother, but shift work seen in factory workers, police and fireman, healthcare staff, and other positions place an additional health burden on these workers. Shift working was found to add an additional 40 percent risk of heart disease as compared to non-shift work.

There is also increased weight gain as a result of decreased glucose tolerance from meals consumed in the night.  When eating at night, your body tends to store more of the calories rather than burn them.  Therefore night workers (who have to eat sometimes) tend to be more overweight.  Researchers have also found that shifts workers have worse cholesterol results.

All of this contributes to increased health problems and premature death.

Shift work is more prevalent in the African American community and is also associated with worse health outcomes including:

• increased smoking
• elevated blood pressures
• obesity
• increased alcohol use
• decreased physical activity
• depression
• work stress

By incorporating a planned exercise schedule and diet, emphasizing the dangers of smoking (particularly in shift workers), and providing better insight into the social impact of these schedules, can help many shift workers.  And the few individuals that continually fail to adjust to shift work may feel better knowing there is a simple explanation for their troubles.

It’s in their genes.

Low Vitamin D in African Americans

Vitamin D is acquired through diet and skin exposure to ultraviolet B light. The skin’s production of vitamin D is determined by length of exposure, latitude, season, and degree of skin pigmentation.  African Americans produce less vitamin D than do White Americans in response to equal levels of sun exposure, and have dramatically lower vitamin D concentrations with some studies indicating up to 96 percent of the African American population as low.  Yet both races tend to have similar capacities to absorb vitamin D and to produce vitamin D when exposed to light. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4030388/)

Overall when measured, African Americans tend to have lower vitamin D3 levels and are very frequently labeled “vitamin D deficient”, but also have confirmed stronger bones and fewer fractures. Powe and colleagues at the Brigham and Woman’s Hospital in Cambridge Massachusetts looked specifically at this paradox and looked at vitamin D3 and vitamin D-binding proteins.

“Lower levels of vitamin D–binding protein in blacks appear to result in levels of bioavailable 25-hydroxyvitamin D that are equivalent to those in whites. These data . . . suggest that low total 25-hydroxyvitamin D levels do not uniformly indicate vitamin D deficiency and call into question routine supplementation in persons with low levels of both total 25-hydroxyvitamin D and vitamin D– binding protein who lack other traditional manifestations of this condition.”

The result of these studies suggest that having both a low vitamin D level and a low vitamin D-binding protein in African Americans actually causes a ‘re-set’ of true deficiency.  With both being low, it is vitamin D’s bioavailability that drives calcium levels, parathyroid hormone levels, and true bone risk.

Dr. Powe concluded:

“Vitamin D deficiency is certainly present in persons with very low levels of total 25-hydroxyvitamin D accompanied by hyperparathyroidism, hypocalcemia, or low BMD (bone mass density). However, community-dwelling blacks with total 25-hydroxyvitamin D levels below the threshold used to define vitamin D deficiency typically lack these accompanying characteristic alterations. The high prevalence among blacks of a polymorphism in the vitamin D–binding protein gene that is associated with low levels of vitamin D–binding protein results in levels of bioavailable 25-hydroxyvitamin D that are similar to those in whites, despite lower levels of total 25-hydroxyvitamin D. Alterations in vitamin D–binding protein levels may therefore be responsible for observed racial differences in total 25-hydroxyvitamin D levels and manifestations of vitamin D deficiency.”

So all of this would suggest that African Americans don’t need Vitamin D replacement or supplements.

Do we need additional Vitamin D or not??

Ken Batai and colleagues at the University of Arizona, after studying over two thousand people, found a direct benefit to Vitamin D supplements to preventing prostate cancer in African American men and a pro-carcinogenic effect (inducing effect) of calcium supplementation on the prostate. These findings were strongest in African Americans.

“Calcium and vitamin D are important nutrients, and they may have preventive effects against many health conditions. Although toxicity from high vitamin D supplementation may be low, high calcium intake is associated with increased prostate cancer risk as well as risk of cardiovascular disease and kidney stones. High calcium consumption might be harmful and for prostate cancer prevention, high dose calcium supplementation and fortification should be avoided, especially among AA (African American) men.”

High calcium intake in African American men may actually increase the risk for prostate cancer, but taking vitamin D can reduce the risk.

Now there is a multivitamin designed just for African Americans. Sequence Multivitamins has high vitamin D, vitamin C, magnesium and much more of what African Americans need, while leaving out those substances that may be harmful.

Diabetes Differences in African Americans

There has been some startling discoveries lately in the differences in how diabetes is diagnosed and treated in African Americans. Because of genetic nuances that we normally may ignore as insignificant, hundreds of thousands of African Americans remain  under-diagnosed and under-treated for diabetes.

Diabetes already occurs at an unusually high rate in African Americans and we are 80 percent more likely to be diagnosed than White Americans.  Of those with diabetes, there is a higher tendency for organ damage (heart disease, kidney failure, or blindness, for example) than Whites.  The prevalence of visual problems, kidney problems, leg amputations, and overall hospitalizations are dramatically higher in African Americans with diabetes.

The CDC reports that African American men die at over twice the rate of any other race or gender group from diabetes. It was also found that these differences were not solely due to the African American diet, genetic differences played a part as well.

Diabetes is diagnosed at an earlier age (median age 49 vs. 55.4 in White Americans) and this earlier age is significant because the development of diabetes complications is directly related to both blood sugar control as well as the total time a person has the disease.  By getting diabetes earlier, there is more time to get complications.  Make sense??

Most research dealing with the increased diabetes in African Americans points to increased insulin resistance when compared to White Americans. This means your body has insulin but is “resistant” to its normal function.

A recent study of over five thousand African Americans curiously showed that heavy smoking (more than a pack of cigarettes a day) significantly increased their risk for diabetes by worsening the insulin resistance.  Former smokers and people who never smoked had a much lower risk for diabetes compared to the heavy smokers.

HbA1c (Hemoglobin-A-One-See), the blood test used to diagnose and track diabetes, is generally a point higher in African Americans (8.9 in White Americans and 9.8 in African Americans), and when controlling for socioeconomic status, quality of care, self-management behaviors, and access, African Americans still have higher HbA1c levels.

Another study by Saaddine and colleagues looked at younger patients age 5 to 24 years and found that African American youths consistently had higher HbA1c levels even without diabetes.

HbA1c is Different in African Americans

In all, HbA1c value differences in African Americans essentially equates to a 0.4% difference (higher) for glucose matched White American patients.  So a HbA1c of 7.0, the normal threshold to diagnose diabetes, is really 7.4 in African Americans.  Diabetes should have been diagnosed when the HbA1c was 6.6.   Put simply, the accepted relationship between HbA1c and the coinciding blood glucose used by doctors and laboratories is different for African Americans.

“The relationship between mean blood glucose and HbA1c may not be the same in all people. Indeed, the published regression line from the “A1c-Derived Average Glucose” (ADAG) Study demonstrated a wide range of average glucose levels for individuals with the same HbA1c levels.” 

If these facts aren’t confusing enough, another study found the HbA1c levels are “less dependable” when they are “near normal” in African Americans.  High and low HbA1c levels tend to be much more accurate when estimating the average blood sugars.

Because of the limitations of HbA1c measurements in some situations and the racial differences discussed above, some of the patients with a HbA1c level between 5.5% and 7% will clearly have diabetes, and others will not.

Another curiosity with HbA1c has to do with patients with a sickle cell trait:

“Among African Americans from 2 large, well-established (studies), participants with sickle cell trait had lower levels of HbA_1c at any given concentration of fasting compared with participants without sickle cell trait. These findings suggest that HbA_1c may systematically underestimate past glycemia in (African American) patients with sickle cell trait and may require further evaluation.” 

Given that one in ten African Americans have sickle cell trait, it is important to consider their trait when interpreting the results of a HbA1c.  In the end, people with sickle cell trait can be tricky to diagnose diabetes.  Many doctors neglect to ask if someone has sickle cell trait because, outside of genetic counseling before having children, there has conventionally been little impact on other disorders.  Is your doctor aware of this genetically-based difference?

More Genetic Differences . . .

A recent study of over 160,00 patients looked at specific genes and how they impacted the diagnosis of diabetes. One in particular, the G6PD gene variant, was found to significantly impact the results of HbA1c tests in African Americans. This specific gene variant is almost totally unique to people of African ancestry.  In fact, about 11 per cent of African Americans carry this gene variant.

“The issue with the G6PD genetic variant is it artificially lowers the value of blood sugar in the HbA1c test, and can lead to under-diagnosis of people with type 2 diabetes. We estimate that if we tested all Americans for diabetes using the HbA1c test, we would miss type 2 diabetes in around 650,000 African Americans.”

Between the 10% of African Americans with sickle cell trait and the 10% with the G6PD gene variant trait, a huge number of African Americans with diabetes are being un-diagnosed or diagnosed late with advanced diabetes.   Diagnosing diabetes as soon as it strikes, gives everyone (the doctor and patient) adequate time to prevent complications before they occur.

If you have just been diagnosed with diabetes, I have a great video that will get you off to a good start below.

If you want to know about other genetic differences look HERE.