In January 2026, the new Dietary Guidelines for Americans put protein, full-fat dairy and "real food" at the center of the plate, and listed butter and beef tallow among acceptable cooking fats. This autumn, 23 nutrition scientists led by Karen Della Corte of Brigham Young University published an International Food Guide Pyramid in Advances in Nutrition that leans the other way: plant foods at the base, beans, fish, poultry and yogurt as preferred proteins, and red meat and butter at the narrow top, to be eaten sparingly. Who is right? On average, the evidence on saturated fat has not changed much. But averages hide people, and a few well-studied genes change how much the butter question matters for you.
What the two guides actually say
| US Dietary Guidelines 2025-2030 | International Food Guide Pyramid | |
|---|---|---|
| Protein | 1.2 to 1.6 g per kg of body weight a day, "protein first" | Plant proteins, fish, poultry and yogurt preferred |
| Saturated fat | Still capped at 10% of calories | Limited: red meat and butter at the top |
| Cooking fats | Olive oil, butter or beef tallow | Healthier fats from plants and fish |
| Where they agree | Less added sugar, fewer refined grains, fewer ultra-processed foods | |
The two guides agree on more than the headlines suggest. The real split is about saturated fat and red meat, and that is exactly where genetics has something to say.
APOE: the gene that makes saturated fat matter more
APOE comes in three common versions, ε2, ε3 and ε4, read from two markers in your raw data (rs429358 and rs7412). About one person in four carries at least one ε4. That version clears LDL cholesterol from the blood less efficiently, and in diet studies ε4 carriers tend to show larger changes in LDL when saturated fat goes up or down (Masson et al., American Journal of Clinical Nutrition, 2003). In the SATgene trial, replacing saturated fat with low-glycaemic carbohydrates lowered total cholesterol and apolipoprotein B more in ε4 carriers than in people with ε3/ε3 (Griffin et al., Nutrients, 2018).
In practice: if you carry ε4, a butter-and-tallow reading of "protein first" is the version of the new guidelines most likely to push your LDL up. If you are ε3/ε3, the effect is usually smaller, though not zero.
APOA2: saturated fat and weight
APOA2 gives one of the most replicated gene-diet interactions in nutrition. In three US populations totalling 3,462 people, those with the less common CC genotype at rs5082 had a 6.2% higher body mass index than other genotypes, but only when they ate 22 g or more of saturated fat a day. With less saturated fat, the difference disappeared (Corella et al., Archives of Internal Medicine, 2009). For scale, 22 g is about three tablespoons of butter.
FTO: who may gain most from more protein
The new protein target is the part of the US guidelines with the least evidence behind it for the general public. One trial gives a genetic angle. In POUNDS Lost, a two-year weight-loss trial, carriers of the FTO risk allele (rs1558902) who followed a high-protein diet lost more fat mass and improved their fat distribution more than non-carriers on the same diet (Zhang et al., Diabetes, 2012). That does not prove that everyone needs more protein, but it suggests some people benefit more than others.
So which pyramid should you follow?
- Everyone: both guides agree on the basics. Cut added sugar, refined grains and ultra-processed food, and eat more vegetables, legumes, whole grains and fish.
- APOE ε4 carriers: keep saturated fat low. Choose olive oil over butter, and fish and legumes over red meat on most days, and have your LDL checked.
- APOA2 CC: watch your saturated fat total, especially if weight is a concern. Below about 22 g a day, the effect disappeared in the studies.
- FTO risk carriers trying to lose weight: a higher-protein pattern may suit you, preferably from fish, poultry, dairy and legumes.
- Everyone else: you have more room, but saturated fat is still not a health food. The 10% cap applies in both guides.
Genes do not replace a blood test. An LDL measurement tells you where you stand today; your genotype helps explain why, and which changes are most likely to move it.
Check your APOE, APOA2 and FTO
All three are read from the raw data file you already have from 23andMe, AncestryDNA or MyHeritage. The Complete report interprets them together with your other lipid and weight genes. Note that APOE ε4 is also linked with Alzheimer's disease risk, something some people prefer not to learn: read our APOE guide before you look.
Educational information, not medical advice. If your LDL cholesterol is high or you take a cholesterol-lowering medicine, discuss diet changes with your doctor.
References
- US Department of Agriculture, US Department of Health and Human Services. Dietary Guidelines for Americans, 2025-2030. January 2026.
- Della Corte K, et al. International Food Guide Pyramid. Advances in Nutrition. 2026. Reported by Food Safety Magazine, 27 October 2026.
- Masson LF, McNeill G, Avenell A. Genetic variation and the lipid response to dietary intervention: a systematic review. Am J Clin Nutr. 2003;77(5):1098-1111.
- Griffin BA, Walker CG, Jebb SA, et al. APOE4 genotype exerts greater benefit in lowering plasma cholesterol and apolipoprotein B than wild type (E3/E3), after replacement of dietary saturated fats with low glycaemic index carbohydrates. Nutrients. 2018;10(10):1524.
- Corella D, Peloso G, Arnett DK, et al. APOA2, dietary fat, and body mass index: replication of a gene-diet interaction in 3 independent populations. Arch Intern Med. 2009;169(20):1897-1906.
- Zhang X, Qi Q, Zhang C, et al. FTO genotype and 2-year change in body composition and fat distribution in response to weight-loss diets: the POUNDS LOST Trial. Diabetes. 2012;61(11):3005-3011.