Calcium & Vitamin D Deficiency: What Your Genes Reveal

Ever wondered why you might struggle with calcium or vitamin D deficiency, even if you eat foods that contain them? Your genes could be a factor, as they affect how the body processes or absorbs certain nutrients. Some people are genetically predisposed to use these nutrients less efficiently than others.

This is where nutrigenomics - the study of how our genes influence the way our body responds to nutrients - comes in. It may sound complicated, but understanding your genetic profile can help explain persistent deficiency symptoms and guide more targeted dietary choices.

The GC gene produces a protein that helps regulate calcium levels by transporting vitamin D to where it's needed in the body. If your GC gene functions normally, your body absorbs calcium from food as effectively as most people, meaning you're likely to need only the standard recommended calcium intake for your age and gender.

Variations of the GC gene can lead to altered levels of this protein, potentially impairing vitamin D metabolism and reducing calcium absorption. This may increase your risk of calcium deficiency, with symptoms such as muscle cramps, dry skin, coarse hair, and brittle nails. Over time, insufficient calcium can progress to more serious conditions like osteopenia or osteoporosis, raising the risk of fractures.

The CYP2R1 gene helps produce an enzyme that converts vitamin D into its most abundant circulating form. The GC gene further helps transport vitamin D to the tissues where it's needed. When these genes function normally, your body processes vitamin D well, and with adequate sunlight exposure and the right foods, you're likely to maintain healthy levels.

Genetic variations in genes like DHCR7, CYP2R1, and GC can contribute to low vitamin D status by affecting its production or activation. Even with sufficient sunlight or vitamin D-rich foods, your body may not use it efficiently. Symptoms of deficiency include muscle weakness and bone pain, and long-term deficiency can lead to rickets in children, osteomalacia, or osteoporosis in adults.

Calcium can be found in dairy products like milk, yogurt, and cheese, or plant-based sources like kale and bok choy. For Malaysians, the Recommended Nutrient Intake (RNI) value for calcium is 800-1000 mg per day for adults.

Foods such as fatty fish (salmon, mackerel, and sardines), egg yolks, fortified dairy products, and fortified plant-based milks are good sources of vitamin D. The RNI for vitamin D in Malaysia is 5-10 mcg per day for adults.

Since vitamin D is a fat-soluble vitamin, eating it alongside healthy fats can improve its absorption. Foods like avocado, olive oil, nuts, and seeds are excellent sources of healthy fats - pairing these with vitamin D-rich items can enhance how efficiently your body absorbs the nutrient.

Vitamin D is often called the "sunshine vitamin" because the body produces it in response to sunlight exposure. Spending time outdoors, particularly in the morning or late afternoon, allows your skin to synthesise vitamin D - around 30 minutes of exposure is usually sufficient to meet daily needs. However, be cautious about sun exposure between 10 AM and 4 PM, as this is when UV radiation is most intense.

If dietary intake cannot meet your calcium and vitamin D needs, supplements can be an option. With a wide variety available, here's how the main forms compare.