Do you know who can donate blood to you or who can you donate blood to? Blood donation may not be complex, but it does need to be compatible with yours and vice-versa. The blood types are determined by the presence or absence of certain antigens - substance that can trigger immune response if they are foreign to the body.

There are four major blood groups which are determined by the presence or absence of two antigens, A and B, on the surface of red blood cells. There is also a protein called the Rh factor, which can either be present (+) or absent (-), which creates A+, A-, B+, B-, O+. O-, AB+, AB- blood types.

Group A blood type has only A antigens on red blood cells and B antibody in the plasma. B has only B antigen on red cells and A antibody in the plasma. AB has both A and antigens on red cells, but neither A nor B antibody is present in the plasma. O has neither A nor B antigens on red cells, but both A and B antibody are present in the plasma.

Blood Type And Who Can You Donate To?

Your blood type determines who can you donate to. This is because there are very specific ways in which blood types must be matched for safe transfusion. The right blood transfusion could actually save you, while the wrong one could be lethal. Also, Rh-negative blood is given to Rh-negative patients and Rh-positive or Rh-negative blood can only be given to Rh-positive patients.

If you are O blood type, you can donate to O, A, B, and AB, if you are A blood type, you can donate to A and AB, if you are B blood type, you can donate to B and AB, however if you are AB, you can only donate to AB.

Who Can You Receive Blood From?

If you are O blood type, you can only receive from O. If you are A, you can receive from type A and O. If you are blood type B, you can receive from type B and O. If you are AB, you are lucky, you can receive blood from O, A, B, and AB.

There are more than 600 other known antigens, the presence or absence of which creates "rare blood types". Certain types are unique to specific ethnic or racial groups, this is why an African-American blood donation can be the best hope for the needs of patients with sickle cell disease, as per the Red Cross Organization.

Universal Blood Donor

Type O is one in high demand, as it can donate blood to anyone. O negative blood type is the universal blood type, which can donate to everyone, especially during the emergency transfusions and for immune deficient infants.

Who Have These Blood Types In US?

In the US, 37% Caucasian, 47% African-American, 39% Asians, and 53% Latino-American are O-positive. However, only 8% of Caucasian, 4% of African-American, 1% Asian, and 4% Latino=Americans are O-negative.

A+: 33% Caucasian, 34% African-American, 27% Asian, 29% Latino-American

A-: 7% Caucasian, 2% African-American, .5% Asian, 2% Latino-American

B+: 9% Caucasian, 18% African-American, 25% Asian, 9% Latino-American

B-: 2% Caucasian, 2% African-American, .4% Asian, 1% Latino-American

AB+:3% Caucasian, 4% African-American, 7% Asian, 2% Latino-American

AB-: 1% Caucasian, .3% African-American, .1% Asian, .2% Latino-American

Fentanyl is an FDA-approved, quick-acting narcotic painkiller that is nearly 100 times more potent than morphine and 50 times stronger than heroin. While it has important medical uses, widespread illicit use has created a public health crisis, with researchers now warning that commonly used addiction treatments are struggling to keep pace.

A study by researchers at the University of California, Los Angeles, found that people who regularly use illicit fentanyl consume opioid doses equivalent to morphine levels hundreds of times higher than the fentanyl doses used in hospitals—far beyond what current addiction treatment protocols were designed to address.

Published in the journal Drug and Alcohol Dependence, the findings suggest these extreme exposure levels contribute to high opioid tolerance, making medications for opioid use disorder (MOUD) less effective and increasing overdose risk.

Although methadone and buprenorphine remain highly effective at reducing overdose deaths, many patients have struggled to start and remain on treatment since fentanyl replaced heroin as the dominant illicit opioid in the US because of the severity of fentanyl withdrawal, the team said.

Daily Intake Far Exceeds Treatment Protocols

The researchers estimated fentanyl exposure using morphine milligram equivalence (MME), a standardized measure that compares the potency of different opioids.

The analysis combined purity data from more than 500 fentanyl samples collected by Drug Checking Los Angeles between September 2023 and January 2026 with surveys of 47 people who regularly used fentanyl.

The researchers estimated that participants consumed an average of 8,887 MME per day.

According to the US Centers for Disease Control and Prevention (CDC), just 2 mg of fentanyl can be lethal for an opioid-naïve person. The study found that the average fentanyl user in Los Angeles consumes roughly 60 times that amount each day.

Tolerance develops not only to the drug's intoxicating effects but also to the respiratory depression that causes overdose, said Dr. Chelsea Shover, associate professor in the Department of Health Policy and Management.

"Now, we find that people are regularly exposed to doses of opioids that would have seemed impossible to me before I started this work," Shover said.

"To put it in perspective, in hospital settings, fentanyl is often dosed in 100-microgram vials. One gram of average-purity fentanyl that we tested had a dose equivalent to more than 1,200 of these vials. So people are getting daily doses that are on par with injecting hundreds of the hospital vials or taking 440 Percocet pills."

Why It Matters for Addiction Treatment

According to the researchers, the potency and variability of illicit fentanyl mean that people are consuming opioid doses far beyond what existing treatment protocols were designed to manage.

"Of course, starting MOUD is going to be harder for fentanyl than it is for heroin," Shover said.

"This study is a great example of where our science was directly informed by lived experience. It is a call to take withdrawal management seriously, with adjuvant therapies, and compassionate approaches."

As a fully synthetic drug, fentanyl is cheaper and easier to produce than heroin. Its high potency also increases the risk of unintentionally consuming dangerous amounts, raising the likelihood of overdose.

"It's no longer, 'how do we treat someone who smokes a gram of fentanyl per day,' it's 'how do we treat someone using thousands of MMEs of oral morphine in fentanyl per day?' That question and its answers feel more accessible, less abstract to clinicians," Shover said.

Standard Treatment Guidelines May Need Updating

The study reinforces concerns among addiction experts that standard treatment regimens for opioid addiction may no longer adequately address patients with extremely high fentanyl tolerance.

Current doses of medications such as buprenorphine and methadone were originally developed to treat heroin and prescription opioid addiction. The findings add to growing calls from clinicians to update treatment guidelines to reflect today's illicit fentanyl market.

"When patients say their withdrawal is not being treated well, it's important to listen," Shover said.

Athletes who spend years training their bodies undergo remarkable physiological changes. Athlete's heart is one of them. It becomes stronger, more efficient, and sometimes even larger. This natural adaptation is known as athlete's heart, a condition that is completely normal in most cases but can occasionally resemble serious heart disease.

What Is Athlete’s Heart?

Understanding the difference between a healthy athletic heart and an underlying cardiac disorder is crucial, especially as awareness grows around sudden cardiac deaths in young athletes.

HealthandMe spoke to Dr. Ruchit Shah, Interventional Cardiologist at Saifee Hospital, Mumbai, who said, “If a person exercises too much, normally more than 60 minutes in most days of the week for a prolonged period of time, the body's need for oxygen and for blood to supply the oxygen rises significantly. This can often be seen in the very intense training regimens of competitive athletes. The heart muscle responds to this extra demand by getting "conditioned" and thickening with time.”

Just like skeletal muscles that get bigger and thicker and with training and exercise, the heart muscle can get bigger and thicker too.

Athlete's heart is usually characterised by a “conditioned heart rate”. People with athlete's hearts will now show symptoms or serious warning signs and thereby won't need a specific treatment for the condition.

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Common Signs Of Athlete’s Heart

Signs include:

• Slow resting heart rate (bradycardia)

• Mild enlargement of the heart on imaging

• Changes on an electrocardiogram (ECG)

• High exercise capacity with no symptoms

Athlete’s Heart Is Different From Cardiac Diseases

The expert also says that athlete's heart is different from serious cardiac diseases like cardiomyopathies, especially hypertrophic obstructive cardiomyopathy (HOCM).

He says, “HOCM is a serious disease, with heart muscle thickening also occurring and causing the left ventricular cavity to narrow. The left ventricle's outflow tract can also become obstructed from this excessive thickening. Athletes with HOCM have a risk of sudden cardiac arrest and death, unlike athletes with athlete's heart.”

An athlete‘s heart, by itself, is considered a benign physiological adaptation and does not require medical intervention.

However, it becomes important to investigate further if an athlete experiences:

• Chest pain during exercise

• Unexplained fainting

• Palpitations

• Shortness of breath out of proportion to exertion

• Reduced exercise performance

• A family history of sudden cardiac death or inherited heart disease

Ignoring these warning signs can delay the diagnosis of potentially serious cardiac conditions. Those who have an athlete’s heart must get periodic cardiac evaluation, do a temporary reduction in training if the diagnosis remains uncertain, and monitor when minor abnormalities are present.

Athlete's heart is proof of the body's extraordinary ability to adapt to sustained physical activity. For most athletes, it represents a healthy, efficient cardiovascular system rather than a medical problem. The challenge lies in distinguishing these normal adaptations from potentially dangerous heart conditions that can look remarkably similar.

Adults under 40 with obesity continue to face a higher risk of cardiovascular disease than their peers with a normal Body Mass Index (BMI), according to a new study published in The Lancet.

The international study, led by researchers at Imperial College London, found that differences in blood pressure and unhealthy cholesterol levels between older adults with obesity and those with a normal BMI have narrowed—or even disappeared—in several high-income countries over the past three decades. In contrast, little or no such improvement was seen among younger adults.

Younger Adults Show No Similar Improvement

The findings suggest that adults under 40 with obesity continue to have higher blood pressure and unhealthy cholesterol levels than those with a normal BMI.

Obesity is a key risk factor for heart disease.

Researchers also found that the use of cholesterol-lowering and blood pressure medications remains low in this age group, supporting the idea that medication has played a key role in reducing cardiovascular risk among older adults.

"While good news for older adults with obesity, our results suggest that cardiovascular health risks remain higher for adults under 40 than for their counterparts with a normal BMI,” said author Ysé d'Ailhaud de Brisis, from the School of Public Health at Imperial.

"Early lifestyle interventions, screening, and, when appropriate, medication in this younger group should be considered to prevent long-term cardiovascular complications linked to obesity," de Brisis added.

Older Adults See Reduced Risk

Since the 1990s, blood pressure and unhealthy cholesterol levels have fallen more rapidly among adults aged 40 to 79 with obesity than among those with a normal BMI in most of the seven high-income countries studied, including England and the US.

The greatest improvements were seen among adults aged 60 to 79. In England and the US older adults with obesity—particularly those with severe obesity—had similar or even lower blood pressure and unhealthy cholesterol levels than those with a normal BMI by the end of the study period.

Heart Medications May Explain the Trend

The researchers said the narrowing gap is largely due to increased use of cholesterol-lowering medications, such as statins, and blood pressure medicines among adults over 40 with obesity.

For example, by the early 2020s, around 70% to 72% of older men with severe obesity in England and the US were taking cholesterol-lowering medication, compared with 40% to 48% of older men with a normal BMI.

“This latest analysis suggests that the observed convergence in cholesterol and blood pressure levels between people aged over 40 with obesity and those with a normal BMI is largely due to statins and other widely accessible medications to reduce cardiovascular risk. That is a significant public health success story, and one we should not lose sight of as new weight-loss medications enter the picture,” said author Lakshya Jain, from the School of Public Health at Imperial.

How Was the Study Conducted?

The researchers analyzed blood pressure and cholesterol data from nearly one million participants across 110 health datasets collected between 1990 and 2024.

The study included people with obesity, overweight and normal BMI from seven high-income countries: England, the US, Japan, South Korea, Taiwan, Thailand and Finland.

The authors also acknowledged limitations of the study such as, the findings may not apply to low- and middle-income countries, where access to cholesterol- and blood pressure-lowering medications is lower. Further, the study could also not assess the impact of different medication doses because prescription data were unavailable.