In a study published in Nature Communications, researchers at UCLA found that breast milk from women living with HIV carries roughly half the tryptophan of milk from women without the virus, an essential amino acid long linked to immunity, growth and brain development. Drawing on more than a thousand milk samples gathered over eighteen months in Zambia, and confirmed among Haitian mothers on treatment, the work offers what its authors call a first metabolic clue to why many children born to HIV-positive mothers, though never infected, remain more vulnerable to illness and developmental harm. T
Lower Tryptophan in Breast Milk of Women With HIV May Help Explain Health Gaps in Their Children
Children exposed to HIV but not infected face higher illness, growth and cognitive risks, with about a 50% higher mortality in low-income settings.
Roughly half as much tryptophan, at every sample across 18 months
Mark
What's the headline here, really? Milk with less of one amino acid?
Mimi
Roughly half as much tryptophan, at every sample point across 18 months. And these kids are uninfected, yet they still face higher illness and, in low-income settings, about 50% higher mortality. This is a candidate reason.
Mark
Why does tryptophan matter so much?
Mimi
It's essential, so infants depend on getting it. It's thought to support immune function, growth and brain development.
Luke
"Thought to" is doing work there. The study measured milk chemistry. It didn't measure what happened to these infants' growth or cognition because of it.
Mimi
Fair. The link to child outcomes is a hypothesis the authors call a possible explanation, not something shown here.
Mark
Where does the shortfall come from?
Mimi
Mothers' blood plasma also had less tryptophan, so the authors point to systemic depletion, likely reduced intestinal absorption, rather than a transfer problem into milk.
Luke
"Likely." That's an inference from the plasma data, not a demonstrated mechanism.
Mark
And it held on treatment?
Mimi
In the Haitian group of 47 women on antiretroviral therapy, yes. That's a small validation cohort, though.
Luke
Also worth noting the Zambian samples come from a 2001 to 2008 trial, and only 38 women were HIV-negative comparisons.
Mark
So should mothers or babies get tryptophan supplements?
Mimi
Not yet. Inflammation can push tryptophan toward neurotoxic metabolites, so adding it blindly might hurt. Animal studies come first.
El Pulso
- Breast milk from women with HIV holds about half the tryptophan of milk from uninfected mothers, and the gap appears at every point across eighteen months.
- Children who are exposed to HIV but never infected still face roughly a 50% higher risk of death in low-income settings, and the cause has remained unexplained.
- Inflammation driven by the virus pulls tryptophan down pathways that can produce neurotoxic byproducts, so the obvious fix could backfire.
- Researchers are moving cautiously, planning animal studies of chronic viral inflammation before any supplementation reaches the roughly 1.3 million infants born each year to mothers with HIV.
In a study published in Nature Communications, researchers at UCLA found that breast milk from women living with HIV carries roughly half the tryptophan of milk from women without the virus, an essential amino acid long linked to immunity, growth and brain development. Drawing on more than a thousand milk samples gathered over eighteen months in Zambia, and confirmed among Haitian mothers on treatment, the work offers what its authors call a first metabolic clue to why many children born to HIV-positive mothers, though never infected, remain more vulnerable to illness and developmental harm. The shortfall appears to reflect depletion across the mother's body, probably from reduced absorption, and the chronic inflammation behind it persists even under effective therapy, a reminder that surviving the virus and thriving from it are not the same thing.
Researchers at UCLA have discovered that breast milk from women living with HIV contains about half as much tryptophan as milk from women without the virus. Tryptophan is an essential amino acid that supports an infant's immune system, growth and brain development, and the finding, published in Nature Communications, may help explain a stubborn puzzle in maternal and child health.
Each year about 1.3 million children are born to women living with HIV. Most are never infected, thanks to effective antiretroviral therapy, yet in low-income settings these exposed but uninfected children still face higher risks of death, infection, poor growth and cognitive difficulties. The authors describe their work as the first metabolic explanation for why that vulnerability persists.
The team examined 1,426 breast milk samples from 326 women in Zambia, collected over eighteen months during a clinical trial, and then checked their results against a group of Haitian mothers on treatment. The tryptophan deficit held at every point, and blood levels were lower too, suggesting the shortfall comes from depletion throughout the body, likely reduced absorption in the gut, rather than a fault in moving the nutrient into milk. The same pattern of inflammation markers and viral-activation compounds appeared even among mothers on therapy.
The researchers urge caution. Because the inflammation that lowers tryptophan can also push it toward harmful byproducts, simply adding more could do damage. Next come animal studies and follow-up of the infants themselves, and only if a safe approach emerges could it reach the children who most need it.
Researchers at UCLA have found that breast milk from women living with HIV carries about half as much tryptophan as milk from women without the virus. Tryptophan is an essential amino acid, and it is thought to matter for an infant's immune function, growth and brain development. The study appears in Nature Communications.
The finding speaks to a long-standing puzzle. About 1.3 million children are born each year to women living with HIV. With effective antiretroviral therapy, most of these children do not become infected. Even so, in low-income settings those who are exposed but uninfected face roughly a 50% higher risk of death, along with more infections, growth problems and cognitive difficulties. Before antiretroviral therapy existed, their mortality was two to three times that of infants not exposed to HIV. Why they stay vulnerable has been a gap in maternal and child health research. The authors describe their work as the first metabolic explanation for it.
The team analyzed 1,426 breast milk samples collected over 18 months from 326 women in Zambia. Of these women, 288 were living with HIV and 38 were not. The samples came from a clinical trial run between 2001 and 2008. Using metabolomics, the researchers measured more than 800 metabolites at several points, from one week after birth through 18 months. They then checked their results in a second group of 47 women in Haiti who were taking antiretroviral therapy. They also measured tryptophan and kynurenine in both milk and blood plasma, to see whether the shortfall was confined to milk or reflected the mothers' wider physiology.
Tryptophan was lower in the milk of women with HIV at every point across the 18 months, by about 50%. The kynurenine-to-tryptophan ratio, a marker of immune activation, was significantly elevated at every visit. Plasma tryptophan was also lower in the mothers with HIV. That suggests the milk deficit comes from depletion throughout the body, likely because of reduced absorption in the intestine, and not from a problem moving tryptophan into milk.
The milk of women with HIV also held more of a recently discovered antiviral compound called ddhC, along with more cytosine and dimethylarginine. These are all consistent with chronic viral inflammation and interferon activation. The pattern persisted in the Haitian group, whose members were on antiretroviral therapy and had higher immune function, so it appears relevant to current treatment settings.
Dr. Grace Aldrovandi, the corresponding author and chief of infectious diseases in pediatrics at UCLA's David Geffen School of Medicine, said tryptophan deficiency and altered metabolism may be a common denominator behind the immune, growth and cognitive differences seen in these children. Dr. Nicole Tobin, the lead author, called it striking that the signature holds even when mothers are on effective therapy. She said that helps explain why the children still need extra support despite advances in HIV treatment.
The researchers caution against acting on the result yet. Inflammation in HIV pushes tryptophan down pathways that can yield neurotoxic metabolites, so simply adding tryptophan without changing those pathways could do harm. The team plans to test in animal models of chronic viral inflammation whether supplementation can safely improve immune function, growth and cognitive development. Later studies will examine whether infants of mothers with HIV have lower systemic tryptophan and handle it differently. Only if safe interventions emerge could they reach the 1.3 million children born each year to women living with HIV.
Citas Notables
Tryptophan deficiency and altered metabolism may serve as a common denominator explaining the immune, growth, and cognitive differences seen in these children.— Dr. Grace Aldrovandi, UCLA David Geffen School of Medicine
This metabolic signature persists even when mothers are on effective antiretroviral therapy.— Dr. Nicole Tobin, lead author, UCLA
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