The Estrogen-Glycan Connection: How Estrogen Loss Drives Biological Aging in Menopause

When estrogen falls during perimenopause and menopause, it doesn't just bring on hot flushes and disrupted sleep. It sets off a chain reaction inside your immune system that speeds up biological ageing and raises long-term risk for conditions like heart disease and osteoporosis, often years before those risks become visible on a standard blood panel. Understanding why this happens, not just that it happens, is the key to doing something about it.

For a fuller picture of how hormones, HRT and biological age fit together, see the complete guide to tracking hormonal ageing.

What happens when estrogen declines

Estrogen is one of the body's most effective natural anti-inflammatories. It protects the lining of your blood vessels, helps regulate immune cell activity, and keeps chronic, low-grade inflammation in check. When estrogen drops, that protection goes with it.

"We know that when estrogen levels are low or non-existent, we get this pro-inflammatory state. The risk of a heart attack increases by a factor of five, because estrogen is very anti-inflammatory on our endothelium, our blood vessel lining, and it helps regulate these cells. We also know that one in two women over the age of fifty develop osteoporosis, and one in three have an osteoporotic fracture, far more common than in men."
— Dr Louise Newson, GP, Menopause Specialist, Founder of Newson Health and the balance app

This is the long-term cost of estrogen loss. The immediate, measurable version of it shows up first in your immune system, specifically in the sugar structures attached to IgG antibodies, known as glycans.

Mechanisms of action: how hormone loss changes your glycans

Every IgG antibody in your bloodstream carries a small glycan structure that acts like a switch, tipping the antibody's behaviour toward calming inflammation or promoting it. Estrogen helps keep that switch in the calmer, anti-inflammatory position by supporting a process called galactosylation, which adds protective sugar structures onto IgG. When estrogen drops, galactosylation drops with it, and the glycan profile shifts toward pro-inflammatory patterns almost immediately. This isn't limited to a single small trial either: population-level data tracking women through the menopausal transition confirm the same pattern, as estrogen and progesterone decline, protective glycans fall while pro-inflammatory ones rise. This shift is what GlycanAge measures and expresses as a biological age.

"When you block the hormones, either estrogen or testosterone, IgG glycans change rapidly and people age up to ten to twenty years in a couple of months. If you restore the hormones, either estradiol or testosterone, this does not happen."
— Prof. Gordan Lauc, Chief Scientific Officer, GlycanAge; Professor of Biochemistry and Molecular Biology, University of Zagreb

The Genos, Harvard and VA study: causality, not correlation

This mechanism isn't theoretical. A study conducted in collaboration between the Genos Glycoscience Research Institute, Harvard Medical School and the Eastern Colorado VA Geriatric Research Education and Clinical Center set out to test it directly, by removing estrogen from healthy women and watching what happened to their glycan age in real time.

Researchers followed 36 healthy premenopausal women who were treated with a GnRH analogue called leuprolide, which lowers hormone levels to those typically seen after menopause. Of these women, 15 had their estrogen restored using a transdermal estradiol patch, while 21 received a placebo patch and remained at postmenopausal hormone levels for six months.

The result was striking. In the placebo group, glycan age rose by a median of 9.1 years in just six months, driven by an increase in the pro-inflammatory Glycan Mature index, and this happened in nearly every woman who received the placebo. In the group given transdermal estradiol, that increase was completely prevented, and glycan age stayed stable. Once estrogen was restored, or once the study ended and natural cycling resumed, glycan age drifted back toward baseline.

The change was largest in women whose glycan age had been lower than their chronological age to begin with, which tells us something important: a youthful immune profile is not fixed, it's actively maintained by hormonal balance, and it can shift quickly when that balance is lost.

Estrogen isn't acting alone, either. Progesterone and androgens also shape immune tone, and the balance between all three hormones, not estrogen in isolation, determines how quickly the immune system ages through the menopausal transition.

What this means for you

If you're navigating perimenopause or menopause, this research points to something more useful than a single test score: a way to see whether the changes you're making, hormonal or lifestyle, are actually protecting your long-term health.

If you're using or considering HRT, testing gives you a way to check whether your treatment is working at the level of your immune system, rather than relying on symptoms alone. Because hormone therapy can shift glycan age within months, retesting every three to four months is generally recommended while you're adjusting HRT, compared with six to twelve months if you're tracking a lifestyle change like diet or exercise instead. Each test uses a simple finger-prick sample you can collect at home, with results typically ready within two to three weeks.

Delivery method matters too. Not all HRT affects inflammation the same way, and for women working with a clinician, glycan testing can help tailor hormone therapy to the individual rather than relying on a one-size-fits-all dose. Testing before starting HRT, and again a few months in, gives you a clearer picture of what estrogen and inflammation actually look like in your own body, not just on average across a study population.

If you're curious what your own glycan profile shows, you can learn more about testing at home.

External sources

• Hoshi RA, Duarte NJC, Nader HB, et al. N-Glycosylation Profiles of Immunoglobulin G and Future Cardiovascular Events. Circ Res. 2024;134(5):e3-e14. doi:10.1161/CIRCRESAHA.123.323623. PMID: 38348651. PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC10923145/

• Franceschi C, Garagnani P, Parini P, Giuliani C, Santoro A. Inflammaging: a new immune-metabolic viewpoint for age-related diseases. Nat Rev Endocrinol. 2018;14(10):576-590. doi:10.1038/s41574-018-0059-4. PMID: 30046148. Link: https://pubmed.ncbi.nlm.nih.gov/30046148/

• Fasero M, Coronado PJ. Cardiovascular Disease Risk in Women with Menopause. J Clin Med. 2025;14(11):3663. doi:10.3390/jcm14113663. PMID: 40507425. PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC12156203/

• Clynes MA, Harvey NC, Curtis EM, Fuggle NR, Dennison EM, Cooper C. The epidemiology of osteoporosis. Br Med Bull. 2020;133(1):105-117. doi:10.1093/bmb/ldaa005. PMID: 32282039. PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC7115830/

• Ercan A, Kohrt WM, Cui J, et al. Estrogens regulate glycosylation of IgG in women and men. JCI Insight. 2017;2(4):e89703. doi:10.1172/jci.insight.89703. PMID: 28239652. PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC5313059/

• Deriš H, Kifer D, Cindrić A, et al. Immunoglobulin G glycome composition in transition from premenopause to postmenopause. iScience. 2022;25(3):103897. doi:10.1016/j.isci.2022.103897. PMID: 35243255. PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC8881712/

• Jurić J, Kohrt WM, Kifer D, Gavin KM, Pezer M, Nigrovic PA, et al. Effects of estradiol on biological age measured using the glycan age index. Aging (Albany NY). 2020;12(19):19756-19765. doi:10.18632/aging.104060. PMID: 33049709. PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC7732334/