Food allergies can be hard to diagnose – and many people suspect a food allergy when it’s actually something else.

Some food allergies are easy to diagnose – like when someone eats peanuts and immediately experiences a rash and swelling. Other food allergies are a bit harder to recognise, and may start later in life.

There is no perfect test to confirm a food allergy and many symptoms may actually indicate a completely different underlying digestive issue.

If you suspect you might have a food allergy it’s important to take the following steps:

1. See your doctor

A physical check-up by a medical professional is an important first step. Your doctor must know your symptoms to be able to help you rule out any other causes. If underlying medical causes are ruled out, your doctor will the use blood tests or a skin prick test to measure your immune response to certain foods.

According to the American College of Allergy, Asthma and Immunology, these tests can be reliable to rule out or determine a food allergy. Tests can often be confirmed by doing a challenge test, where you have to consume small portions of the food in increasing amounts over a certain time to see if there is an allergic reaction. It’s important that this is performed under the supervision of an allergist.

2. Try the elimination diet

If you know that your symptoms are not caused by any other digestive issues, your doctor might suggest that you try the elimination diet – where you eliminate the suspect food(s) from your diet and gradually reintroduce them.

Although elimination helps to link your symptoms to certain foods, it’s not the perfect way to diagnose a food allergy. You might just have a food intolerance, not an actual allergy.

3. Keep a food diary

Keep a meticulous food diary, making careful notes about what you eat and the resulting symptoms. This can point your doctor in the right direction and help you answer vital questions during your examination. 

4. Visit a registered dietitian

If you have established that key food groups in your diet are causing your symptoms, it’s a good idea to ask a nutritional expert about alternative ways to obtain essential nutrients.

5. Don’t self-diagnose – ever

If digestive symptoms such as stomach cramps are interfering with your daily life and you suspect a food allergy, get the opinion and the diagnosis of a medical professional. There might be an underlying medical condition that you are unaware of.

You should also know the difference between a food intolerance and a food allergy. An intolerance can cause unpleasant symptoms such as nausea, stomach ache or other digestive issues, while a food allergy can be life-threatening in the case of anaphylaxis.

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Marelize Wilke

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When someone with HIV has the virus suppressed with medication, there is virtually no chance of passing it on to sex partners, a new review concludes.

The Public Health Agency of Canada pulled together studies from the last decade looking at the risk of HIV transmission among partners where one person is HIV-positive and one is not.

Even without condoms

It found there were no cases of transmission when the HIV-positive partner was on drug “cocktails” that were keeping the virus suppressed. “Suppressed” means there are fewer than 200 copies of the virus per millilitre of blood.

In those cases, the review found, there were no HIV transmissions even when couples did not use condoms.

Experts said the findings are good news for people living with HIV – and have implications for current laws in Canada, the United States and elsewhere.

At issue are laws that subject HIV-positive people to possible criminal prosecution for not telling their sexual partners about their status. They exist in Canada and many US states.

But the laws are “rooted in the 1980s view of the disease”, said Perry Halkitis, dean of the School of Public Health at Rutgers University in Piscataway, New Jersey.

That is, they reflect an era when HIV was a death sentence instead of the manageable chronic condition it is today. Drug therapies that first became available in the 1990s changed the face of HIV treatment.

Impact of findings

And in recent years, Halkitis said, studies have offered “a ton of evidence” that when those drugs suppress the virus, it is not transmissible to person’s sex partners.

“These criminalisation laws do nothing but stigmatise HIV-positive people. They need to be revisited,” said Halkitis, who was not involved in the new research.

In Canada, the findings have already had an impact. The Department of Justice Canada, which collaborated on the review, issued a report last December saying that criminal law should no longer apply to HIV-positive people who have their virus suppressed by medication.

Its report also said the laws should not apply to people who are not on medication but use condoms during sex. In the research review, the risk of HIV transmission in those cases was deemed to be “low” – at just over 1 transmission for every 100 people per year.

The health agency used the word “negligible” to describe the risk of transmission when the virus is suppressed by medication. That means there is a theoretical risk of transmission because there is an “exchange of bodily fluids that carry the virus,” officials said – but no actual confirmed cases.

“We hope these findings help people living with HIV and their partners to make decisions, and that they help reduce the stigma experienced by people living with HIV,” the agency said.

‘HIV-specific’ criminal laws

The latest review, led by the agency’s Dr Rachel Rodin, is based on 11 studies and one previously published research review. The studies followed steady partners – both heterosexual and same-sex – in various countries.

The results were published in the CMAJ: Canadian Medical Association Journal.

In the United States, 29 states have “HIV-specific” criminal laws, according to the non-profit Center for HIV Law & Policy (CHLP). That includes laws that target people who fail to disclose their HIV status to sexual partners.

Many medical organisations, like the American Medical Association and American Psychological Association, have long called for reform of those criminal laws. And the CHLP and other groups argue that it’s not enough to exempt HIV-positive people who have their virus suppressed through medication.

‘Grounded in scientific evidence’

The CHLP points to the fact that Americans have unequal access to health care, and certain groups – including blacks and the poor – face more obstacles in keeping their HIV levels suppressed.

That means they are unfairly targeted by criminal laws, the CHLP says.

Halkitis agreed that having HIV-specific laws at all is problematic. No other transmissible disease is subject to such criminal prosecution, he pointed out.

“We have to stop reacting to HIV like it’s still the 1980s,” Halkitis said. And that, he added, includes having policies that are “grounded in scientific evidence”.

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People with dementia show a different makeup in the bacteria dwelling in their guts, a preliminary study finds – raising questions about whether the “bugs” play some role in the brain disease.

Researchers in Japan found that compared with dementia-free older adults, those with the disease typically had a very different gut “microbiome”. The term refers to the trillions of bacteria and other microbes dwelling in the digestive system.

Differing gut microbes

As recent studies have been revealing, those gut bugs do more than aid digestion. They appear to affect a range of bodily functions, from immune defences to the production of vitamins, anti-inflammatory compounds and even chemicals that relay messages among brain cells.

Researchers have also found that the makeup of the gut microbiome is linked to risks for various conditions, such as obesity, asthma and type 1 diabetes.

Those studies do not prove that gut bacteria directly contribute to, or protect against, those diseases, however. And neither does the new study, experts stressed.

The study found only that a group of dementia patients had different gut microbes from dementia-free adults, said Mary Sano, director of the Alzheimer’s Disease Research Center at Mount Sinai in New York City.

“You’d expect to see a lot of differences between those two groups of people,” said Sano, who was not involved in the study.

And it’s very possible, she said, that the dementia was the cause of the gut differences, not the result. For example, diet is critical in the makeup of gut bacteria, and people with dementia often have changes in appetite and end up malnourished.

‘We don’t know which came first’

Keith Fargo is director of scientific programmes and outreach for the Alzheimer’s Association. He made the same point.

“At this point, we don’t know that this association is causal,” said Fargo, who was not involved in the study. “We don’t know which came first – the dementia or the differences in the gut microbiome.”

The findings are scheduled to be presented at an American Stroke Association conference in Honolulu next week. Research reported at meetings should be considered preliminary until published in a peer-reviewed journal.

For the study, Dr Naoki Saji and colleagues at the National Center for Geriatrics and Gerontology in Obu, Aichi, Japan, analysed stool samples from 128 older adults – with and without dementia.

In general, the investigators found, dementia patients had higher concentrations of certain compounds – including ammonia, indole and phenol – but lower levels of Bacteroides.

Bacteroides are a group of bacteria that can be beneficial in the gut because they crowd out “bad”, infection-causing bugs.

Bacteria attack nerve cells

For now, Fargo said, the relationship between the gut microbiome and disease is an interesting, “burgeoning” area of research. But whether the microbes have any direct effect on dementia risk is unknown.

Other recent studies have looked at whether chronic infection has any connection to dementia. Just last week, researchers reported finding the bacteria that cause gum disease in the brains of people with Alzheimer’s.

In tests of mice, they showed that the bacteria could travel from the mouth to the brain, where they attacked nerve cells.

Still other research has found particularly high levels of certain strains of herpes virus in the brains of people with Alzheimer’s.

It all raises the possibility that “external organisms” might play some role in dementia, according to Fargo. But, he stressed, no one yet knows what’s going on.

Keeping blood pressure down

Sano agreed. She said that although the presence of certain infectious bugs has been linked to dementia, it might not be the infections, themselves, that matter. Gum disease bacteria and herpes viruses are extremely common, Sano pointed out. So carrying those bugs, alone, is not the critical factor.

Instead, Sano speculated, there may be something about the body’s general response to “insult or injury” that is the real problem.

Fargo recommended that people focus on lifestyle factors that have been solidly tied to better brain health: Get regular exercise, don’t smoke and eat a heart-healthy diet.

He also pointed to the importance of keeping blood pressure down. A major trial published this week found that “intensive” blood pressure control – below 120 mm Hg – lowered older adults’ risk of developing milder problems with memory and thinking.

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